#algos-and-data-structs | Python | Page 18

haughty mountain Nov 4, 2022, 9:25 PM

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fwiw, the more traditional chained hashtables are easier to analyze

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in the probing hash table different probing chains interact with each others

fiery cosmos Nov 4, 2022, 9:28 PM

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i still could never figure out how to catch strings in the input. the way i im reading the data now perturbs that and i wasn't able to implement your proposed data reading strategy

fiery cosmos Nov 4, 2022, 10:09 PM

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hey my count function is messed up for when bucketsize is 3

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right now it's this:

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which was working for regular buckets of size 1

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its like way wrong like im getting load factor of 8

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its counting the correct number of elements

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nvm, i just needed parenthesis 🤦‍♂️

haughty mountain Nov 4, 2022, 10:24 PM

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yeah, I was about to say

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parens matter

fiery cosmos Nov 4, 2022, 10:26 PM

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i'm actually really surprised she doubled down on being wrong about the tablesize mod. its fine to be wrong, but the way you handle it matters

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i wrote two completely separate programs

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and neither are great, but at least i have a real load factor to work with

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i have a vague feeling like the probe computation isn't what she wants, beyond just the modulo thing

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oh yeah i see how quadratic probing is broken

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oh wait this was chaining 🤔

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somehow my chaining broke

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for both programs. so weird

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must have been some comparison logic i added

fiery cosmos Nov 4, 2022, 11:12 PM

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chain you chain together logical operators

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sry logic

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like
if var1 is not < var2

stiff plover Nov 4, 2022, 11:37 PM

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fiery cosmos like `if var1 is not < var2`

is this correct syntax?

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if not var1 < var2:?

fiery cosmos Nov 4, 2022, 11:37 PM

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probably not

dreamy valley Nov 4, 2022, 11:43 PM

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fwiw, not < is usually spelled >=

haughty mountain Nov 4, 2022, 11:47 PM

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dreamy valley fwiw, `not <` is usually spelled `>=`

!e let me be the terrible person to throw nan at you as a counterexample

nan = float('nan')
print(not nan < nan)
print(nan >= nan)

halcyon plankBOT Nov 4, 2022, 11:47 PM

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@haughty mountain :white_check_mark: Your 3.11 eval job has completed with return code 0.

001 | True
002 | False

dreamy valley Nov 4, 2022, 11:52 PM

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💯% right, and maybe thinking about that would clarify in someone's mind why they want not < over >=

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gotta love floating point

stray fractal Nov 5, 2022, 1:25 AM

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haughty mountain !e let me be the terrible person to throw nan at you as a counterexample ```py n...

x != x or x >= x

vital scaffold Nov 5, 2022, 5:25 AM

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Hmm, now i understand that doing in-place operations just alters the list while doing something like

def test(nums):
  list = x
  x = x + [1] # x now  references to a new list so there is no alteration in the original list

arr = [1,2,3]
print(test(arr))

`[1,2,3]

inland crane Nov 5, 2022, 4:20 PM

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Hey can anyone help me understand how one is supposed to implement a backtracking problem iteratively??

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Is it true that any problem can be solved both recursively and iteratively? Or are there certain instances where that isn't the case...

shut breach Nov 5, 2022, 6:18 PM

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all recursive programs can be written iteratively and vice versa

fiery cosmos Nov 5, 2022, 6:18 PM

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hi all, i think my logic for my chaining insertion scheme could be incorrect

fiery cosmos Nov 5, 2022, 6:19 PM

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shut breach all recursive programs can be written iteratively and vice versa

right, and this is not the same as what @inland crane had implied, that any problem can be solved recursively

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not all problems have recursive structure

fiery cosmos Nov 5, 2022, 6:19 PM

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fiery cosmos hi all, i think my logic for my chaining insertion scheme could be incorrect

for my hashtable algorithm

cold bluff Nov 5, 2022, 6:27 PM

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is there some resources for a bit more intermediate algorithms n data structure? Especially for leetcode

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and also some math courses? I'm kinda bad in math

fiery cosmos Nov 5, 2022, 6:35 PM

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for math you can do khan academy and schaums outlines (physical books) which are very good for getting back up to speed with things you may have forgotten. khan academy is invaluable. then you can move on to the pinned course in this channel

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hi all,
if each insertion of a hashtable could be O(n) in worst case, and there are n elements, it theoretically could take n^2 time to insert them all, yeah?

lyric berry Nov 5, 2022, 6:38 PM

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so if i wanted to make a graph or tree data structure, with a bunch of objects as nodes and be able to access connected nodes via an attribute is that possible

fiery cosmos Nov 5, 2022, 6:39 PM

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of course. might be easier with an adjacency list though

lyric berry Nov 5, 2022, 6:39 PM

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for example using

for node in node5.children:
[do work on node objects]

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node.children would have to contain a list of references. but python doesnt have references?

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so how would you implement that

fiery cosmos Nov 5, 2022, 6:42 PM

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so typically a tree structure based on a node class just has pointers as attributes. eg, node.leftchild = node4

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adjacency lists make everything easy, for graphs

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trees and graphs can be quite different

lyric berry Nov 5, 2022, 6:43 PM

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yea thats how i would do it in c, using pointers

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im specfically asking how to do it using object references not a adjecency chart

opal oriole Nov 5, 2022, 6:43 PM

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Everything in Python is a PyObject *.

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= copies the pointer.

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(Like in C)

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So if you make a new_var = some_obj, they both reference the same object.

lyric berry Nov 5, 2022, 6:44 PM

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oh ive been out of python for a while i thought it did a copy

fiery cosmos Nov 5, 2022, 6:44 PM

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you'd recursively gather up all the children by calling a method on a node that would get all it's children first, then do something will all of the children you have gathered. it should be easier though if each node is the root of the subtree of all of its children

opal oriole Nov 5, 2022, 6:45 PM

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lyric berry oh ive been out of python for a while i thought it did a copy

Deep copy requires the copy library, which is built in.

fiery cosmos Nov 5, 2022, 6:45 PM

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then you just say do something for the subtree with this node as the root

cold bluff Nov 5, 2022, 6:45 PM

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fiery cosmos for math you can do khan academy and schaums outlines (physical books) which are...

khanacademy comes a bit wierd to me like I currently finished a 2 year degree in computer programming but my highschool math wasn't totaly complete

lyric berry Nov 5, 2022, 6:45 PM

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opal oriole Deep copy requires the copy library, which is built in.

yea i thought doing deep copy was the default my bad

cold bluff Nov 5, 2022, 6:45 PM

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cold bluff khanacademy comes a bit wierd to me like I currently finished a 2 year degree in...

I tried to look from there but some stuff are too basic. When I skip then again I skip too much material

fiery cosmos Nov 5, 2022, 6:46 PM

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cold bluff khanacademy comes a bit wierd to me like I currently finished a 2 year degree in...

i think khan academy is excellent one day i'd like to go through all of it and properly learn linear algebra and regression analysis

opal oriole Nov 5, 2022, 6:46 PM

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lyric berry yea i thought doing deep copy was the default my bad

Yeah just remember PyObject *.

fiery cosmos Nov 5, 2022, 6:46 PM

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cold bluff I tried to look from there but some stuff are too basic. When I skip then again ...

you literally have to painfully go through all of it

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i've been there

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i have 2 schaums outlines

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one in rudimentary algebra and one in discrete

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i took calc and stats in college and forgot all of it

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i want to learn linear, as i said

cold bluff Nov 5, 2022, 6:47 PM

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fiery cosmos you literally have to painfully go through all of it

like for example I know some stuff about till like functions in math. Idk the what exactly algebra and like discrete math is

fiery cosmos Nov 5, 2022, 6:47 PM

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and multiple linear regression

cold bluff Nov 5, 2022, 6:47 PM

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but my geometry was really bad

fiery cosmos Nov 5, 2022, 6:48 PM

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cold bluff like for example I know some stuff about till like functions in math. Idk the wh...

you don't know what algebra is?

cold bluff Nov 5, 2022, 6:48 PM

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like w the triangles

fiery cosmos Nov 5, 2022, 6:48 PM

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eh, you don't really need that

cold bluff Nov 5, 2022, 6:48 PM

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cold bluff like w the triangles

our entrance exam is based on that

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mostly circles n triangles

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for geometry

cold bluff Nov 5, 2022, 6:48 PM

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fiery cosmos you don't know what algebra is?

we just have like some topics

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idk if it is in algebra or not

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I also like to watch it in english

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soo like because of that idk even what to watch in khanacademy

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maybe thats why it was a bit bad experience for me

opal oriole Nov 5, 2022, 6:53 PM

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Eh, IDK if I can share that due to rules.

cold bluff Nov 5, 2022, 6:53 PM

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is pay to learn...

opal oriole Nov 5, 2022, 6:54 PM

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Yeah.

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But it's that or $200 books.

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Or Khan.

cold bluff Nov 5, 2022, 6:56 PM

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opal oriole But it's that or $200 books.

I could find some books

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idk which ones tho

fiery cosmos Nov 5, 2022, 7:29 PM

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schaums outlines

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https://www.amazon.com/dp/B09ZP6Q2NC?binding=kindle_edition&searchxofy=true&ref_=dbs_s_aps_series_rwt_tkin&qid=1667676576&sr=8-6

Schaum's Outlines

Visit Amazon's Schaum's Outlines Page and shop for all Schaum's Outlines books. Check out pictures, author information, and reviews of Schaum's Outlines

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ooh i should grab the linear algebra one

opal oriole Nov 5, 2022, 7:33 PM

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cold bluff I could find some books

I am going to show you some stuff and you tell me if you think it's in there.

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#

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haughty mountain Nov 5, 2022, 7:39 PM

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opal oriole Nov 5, 2022, 7:40 PM

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Do any of these seem like they are something you need to learn about?

fiery cosmos Nov 5, 2022, 7:51 PM

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wow y'all are always on the ball, even on saturdays. bravo 👏 👏 👏

vocal gorge Nov 5, 2022, 8:09 PM

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versin? exsec?? excsc??? wow, they really just keep making up functions :p

opal oriole Nov 5, 2022, 8:10 PM

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cold bluff like for example I know some stuff about till like functions in math. Idk the wh...

Algebra (derived from الجبر "al-jabr" (meaning "restoration" or "completion")) is "Calculation by Completion and Balancing". It's when you have equations such as 3x = 10. Them being equal to each other means they are balanced.

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A set of rules for solving such algebraic equations is known as an "algorithm" (algorism) (name also given by same person, محمد بن موسی خوارزمی (Muhammad ibn Musa al-Khwarizmi)).

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And in many algebra classes you memorize many such algorisms.

dusk anchor Nov 5, 2022, 8:20 PM

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vocal gorge versin? exsec?? excsc??? wow, they really just keep making up functions :p

exsecant/exsec(θ) is sec(θ)-1
excosecant/excsc(θ) is csc(θ)-1

vocal gorge Nov 5, 2022, 8:21 PM

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huh, never saw that - why not call them arcsec/arccsc like everything does?

fiery cosmos Nov 5, 2022, 8:25 PM

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opal oriole A set of rules for solving such algebraic equations is known as an "algorithm" (...

ooooohh

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algebra and algorithm

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v curious

dusk anchor Nov 5, 2022, 9:06 PM

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vocal gorge huh, never saw that - why not call them arcsec/arccsc like everything does?

Its pretty much the same. But the name is not just joining func names

brisk saddle Nov 5, 2022, 9:20 PM

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hey, so i had an interesting thought when it comes to string searching.

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this might be the same as doing a regular check if a word appears at index n in a string, but:

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actually, nevermind.

dusk anchor Nov 5, 2022, 10:13 PM

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lol

haughty mountain Nov 5, 2022, 11:12 PM

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brisk saddle actually, nevermind.

👀

brisk saddle Nov 5, 2022, 11:13 PM

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👁‍🗨

haughty mountain Nov 5, 2022, 11:14 PM

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opal oriole

interesting that they used exscs and exsec which makes it very not obvious that the terms are related

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external secant and external cosecant

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they go with tan and cotan

brisk saddle Nov 5, 2022, 11:16 PM

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opal oriole

thanks i hate it

haughty mountain Nov 5, 2022, 11:16 PM

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vocal gorge versin? exsec?? excsc??? wow, they really just keep making up functions :p

versin is actually important

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or was

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for navigation

brisk saddle Nov 5, 2022, 11:17 PM

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theres also the haversine

haughty mountain Nov 5, 2022, 11:17 PM

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you would have tables of haversine (half versine)

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right

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https://en.wikipedia.org/wiki/Haversine_formula

Haversine formula

The haversine formula determines the great-circle distance between two points on a sphere given their longitudes and latitudes. Important in navigation, it is a special case of a more general formula in spherical trigonometry, the law of haversines, that relates the sides and angles of spherical triangles.
The first table of haversines in Englis...

brisk saddle Nov 5, 2022, 11:17 PM

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im pretty sure all of them can be derived from the base 3 trig functions

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and tan can be derived from sin and cos

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and cos can be derived from sin

haughty mountain Nov 5, 2022, 11:18 PM

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you can get by with 1

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yeah

brisk saddle Nov 5, 2022, 11:18 PM

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its sin all the way down

haughty mountain Nov 5, 2022, 11:18 PM

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✝️

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begone daemon

brisk saddle Nov 5, 2022, 11:18 PM

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yeah that about sums it up

haughty mountain Nov 5, 2022, 11:18 PM

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I hope that joke landed

brisk saddle Nov 5, 2022, 11:19 PM

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lol

opal oriole Nov 5, 2022, 11:22 PM

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haughty mountain interesting that they used exscs and exsec which makes it very not obvious that ...

The names don't really make sense and are only partially fixed in post. They are mistranslated through multiple languages over thousands of years.

haughty mountain Nov 5, 2022, 11:23 PM

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opal oriole The names don't really make sense and are only partially fixed in post. They are...

yeah, most of the base names are terrible (looking at you sine) but there is a systematic naming on top of that

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feels weird to hide the actually nice systematic part of it

opal oriole Nov 5, 2022, 11:24 PM

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The base needs to be accepted as its own made up words (slightly latin based), since that was translated incorrectly.

haughty mountain Nov 5, 2022, 11:24 PM

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isn't sine the only base?

opal oriole Nov 5, 2022, 11:25 PM

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Cosine and tangent has their own words.

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Tangent is the only decently translated.

haughty mountain Nov 5, 2022, 11:25 PM

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cosine is a derived term

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from sine

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co- as a (systematic) prefix

opal oriole Nov 5, 2022, 11:26 PM

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Yea after translation.

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They needed a word for cosine, and were like, let's just add "co".

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The older original words are related to construction.

haughty mountain Nov 5, 2022, 11:27 PM

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co is... err

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complementary?

opal oriole Nov 5, 2022, 11:27 PM

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Yea more or less, but the Latin root version.

haughty mountain Nov 5, 2022, 11:27 PM

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yeah

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tangent and secant are established names already

opal oriole Nov 5, 2022, 11:28 PM

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Tan and cotan make more sense in that regard.

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Cause if the total line is length say, 1, then cotan 1 - tan

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So the complement.

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Like in probability.

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Sin and cos are a bit more complicated, related through the right triangle.

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So not exactly complement.

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(Unless you go by the squares)

haughty mountain Nov 5, 2022, 11:30 PM

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it's complimentary in the sense of that one somewhat important trig identity, yes

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iirc there is a nice symmetry of all the co- stuff

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with the non co- stuff

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the non co- version is based on the triangle on one side of the angle

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the co is the same but for the other side of the angle

dreamy valley Nov 5, 2022, 11:35 PM

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cofunc(θ) = func(π/2 - θ)

haughty mountain Nov 5, 2022, 11:35 PM

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not that I actually know most of these terms off hand

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if I need them I usually just represent them in the usual 3

dreamy valley Nov 5, 2022, 11:36 PM

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I assume that's why they made me memorize that angles that add to π/2 are called "complementary"

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er

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fixed lol

agile sundial Nov 5, 2022, 11:37 PM

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complimentary is pi/2 i thought

haughty mountain Nov 5, 2022, 11:37 PM

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lol, I was about to say

opal oriole Nov 5, 2022, 11:37 PM

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haughty mountain not that I actually know most of these terms off hand

Wolfram math world to the rescue when you need it.

dreamy valley Nov 5, 2022, 11:37 PM

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knew there was something wrong about that

haughty mountain Nov 5, 2022, 11:37 PM

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before I saw the edit

opal oriole Nov 5, 2022, 11:37 PM

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External memory storage, don't need to remember everything, just the general idea and how it can be used.

haughty mountain Nov 5, 2022, 11:37 PM

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so yeah, they are related to the complementary angle

dreamy valley Nov 5, 2022, 11:38 PM

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guess I didn't memorize things as well as I thought

haughty mountain Nov 5, 2022, 11:38 PM

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(wrt pi/2)

opal oriole Nov 5, 2022, 11:38 PM

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Or just 1 - theta if you are not using radians.

haughty mountain Nov 5, 2022, 11:39 PM

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I recall in a bunch of US material more than the usual 3 functions

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like cot scs and...what's the last one?

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csc?

opal oriole Nov 5, 2022, 11:39 PM

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csc

dreamy valley Nov 5, 2022, 11:39 PM

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if you are using degrees it would be 90° - θ

opal oriole Nov 5, 2022, 11:39 PM

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Degrees are for people using base 60.

haughty mountain Nov 5, 2022, 11:40 PM

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opal oriole Or just 1 - theta if you are not using radians.

what angle measurement is that even?

opal oriole Nov 5, 2022, 11:40 PM

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We can become French revolutionaries and use gradians.

haughty mountain Nov 5, 2022, 11:40 PM

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4 somethings is a revolution?

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I know there is a 400 degree thing

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but I've not seen 4

opal oriole Nov 5, 2022, 11:40 PM

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haughty mountain I know there is a 400 degree thing

Gradians ("new degree")

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There are a whole bunch others, including 2pi = 1

dreamy valley Nov 5, 2022, 11:41 PM

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haughty mountain 4 somethings is a revolution?

it's quite simple, we define π = 2

haughty mountain Nov 5, 2022, 11:41 PM

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opal oriole There are a whole bunch others, including 2pi = 1

aka a revolution is 1 revolution

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radians are nice though

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because the whole arc length thing

opal oriole Nov 5, 2022, 11:42 PM

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"turns" https://en.wikipedia.org/wiki/Angle#Units

Angle

In Euclidean geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.
Angles formed by two rays lie in the plane that contains the rays. Angles are also formed by the intersection of two planes. These are called dihedral angles. Two intersecting curves may also...

haughty mountain Nov 5, 2022, 11:42 PM

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yeah, I guess it's the more usual term

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what's the relevant term from complex analysis...

dreamy valley Nov 5, 2022, 11:43 PM

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I use all three at work (degrees, radians, turns)

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degrees mostly for axis labels though

haughty mountain Nov 5, 2022, 11:43 PM

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haughty mountain what's the relevant term from complex analysis...

related to the residue theorem

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winding number

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I guess that doesn't translate to a nice term, huh?

opal oriole Nov 5, 2022, 11:45 PM

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Not sure. Knowing math there is probably a term for it.

haughty mountain Nov 5, 2022, 11:45 PM

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well, winding is about the process of...winding something around the origin

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I suspect turn could be the appropriate unit

opal oriole Nov 5, 2022, 11:46 PM

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Turn feels ok.

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Or cycle, or revolution.

haughty mountain Nov 5, 2022, 11:46 PM

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revolution for sure pops up in practical applications

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rpm and whatnot

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someone should be terrible and shorten rad/s as rpm

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but in the grand scheme radians is the "right" choice for mathematics

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a bit like how e is the right choice for exponentials

opal oriole Nov 5, 2022, 11:49 PM

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It's kind of arbitrary, but results in better equations than something like degrees.

haughty mountain Nov 5, 2022, 11:49 PM

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(and these are somewhat related, radians and e)

opal oriole Nov 5, 2022, 11:49 PM

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Which is subjective somewhat (shorter equations typically preferred).

haughty mountain Nov 5, 2022, 11:50 PM

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opal oriole It's kind of arbitrary, but results in better equations than something like degr...

well, that kinda removes the arbitrariness, doesn't it?

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it removes a bunch of leading factors popping out when doing math on it

opal oriole Nov 5, 2022, 11:50 PM

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KInd of, because one can just collapse them often.

dreamy valley Nov 5, 2022, 11:51 PM

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it can be arbitrary, but it can be practical too.
You minimize floating point error by doing math with all numbers that are more or less close to 1.0

opal oriole Nov 5, 2022, 11:51 PM

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Which is effectively the same as changing to radians or whatever.

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Yeah in CS, which is on topic, it can show up better to no use radians, which many implementations do.

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For by-hand, degrees can make sense if you use base 60, but we don't typically do that anymore.

haughty mountain Nov 5, 2022, 11:52 PM

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opal oriole Which is effectively the same as changing to radians or whatever.

yeah sure, but in math we would like to go for the thing that causes us less pain 😛

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wrong message to reply to, but whatever

opal oriole Nov 5, 2022, 11:53 PM

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haughty mountain yeah sure, but in math we would like to go for the thing that causes us less pai...

Gotta max out the lazy-ness, but also can just not care these days and let mathematica figure it out.

haughty mountain Nov 5, 2022, 11:53 PM

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opal oriole Gotta max out the lazy-ness, but also can just not care these days and let mathe...

well, you still need to feed something sensible into mathematica

opal oriole Nov 5, 2022, 11:54 PM

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haughty mountain well, you still need to feed something sensible into mathematica

Yeah, but much less.

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I can give some ridiculous stuff to it in 2022.

haughty mountain Nov 5, 2022, 11:54 PM

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physicists do fun stuff as well, e.g. let c = 1

opal oriole Nov 5, 2022, 11:54 PM

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(And eventually when they use more ML, almost anything that is not complete nonsense)

haughty mountain Nov 5, 2022, 11:55 PM

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(and let a bunch of other things = 1)

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what's the name, natural units?

opal oriole Nov 5, 2022, 11:55 PM

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Uh, nats?

haughty mountain Nov 5, 2022, 11:55 PM

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planck units

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is one version at least

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is has some fun consequences for units relevant to us mortals though

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opal oriole Nov 5, 2022, 11:58 PM

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"The universe does not care about what you prefer"

haughty mountain Nov 5, 2022, 11:58 PM

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momentum is surprisingly human sized

opal oriole Nov 5, 2022, 11:59 PM

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Energy is also ok.

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Only kind of big.

vocal gorge Nov 6, 2022, 1:10 AM

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haughty mountain momentum is surprisingly human sized

it's the momentum of a single photon with planck wavelength 🥴

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so it's, like, a basketball's worth of momentum in one photon

agile sundial Nov 6, 2022, 1:11 AM

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opal oriole Only kind of big.

definitely enough to cook a chicken

haughty mountain Nov 6, 2022, 1:13 AM

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vocal gorge it's the momentum of a single photon with planck wavelength 🥴

(ignoring a factor of 2pi)

cold bluff Nov 6, 2022, 6:38 AM

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opal oriole I am going to show you some stuff and you tell me if you think it's in there.

yea is in there

rough wharf Nov 6, 2022, 1:57 PM

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how can we use linkedlist in quicksort

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is there any way

agile sundial Nov 6, 2022, 2:00 PM

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you generally wouldn't use quicksort for linked lists, since it requires random access

rough wharf Nov 6, 2022, 2:21 PM

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ohh okay

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then for linked list which algo we should use ?

meager slate Nov 6, 2022, 2:31 PM

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my guess is you can use insertion sort

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the reason insertion sort is O(n^2) is because inserting in the middle in a vector (list) is O(n)

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but for linked lists it is O(1)

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so maybe you can take advantage of that

agile sundial Nov 6, 2022, 2:32 PM

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mergesort

dreamy valley Nov 6, 2022, 2:32 PM

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meager slate but for linked lists it is O(1)

regrettably, that is not correct

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inserting at a cursor in a linked list is O(1)

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but in an insertion sort you have to find the cursor first

agile sundial Nov 6, 2022, 2:33 PM

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meager slate the reason insertion sort is O(n^2) is because inserting in the middle in a vect...

insertion sort isn't N^2 because of actually inserting, it's N^2 because of how it selects the next element and swaps it into the correct spot

meager slate Nov 6, 2022, 2:33 PM

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oops

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my bad

dreamy valley Nov 6, 2022, 2:33 PM

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there is no efficient (O(n log n)) in-place sort on linked lists, but mergesort would work as a not-in-place one

#

treesort maybe

meager slate Nov 6, 2022, 2:34 PM

#

what about a heapsort?

dreamy valley Nov 6, 2022, 2:34 PM

#

if you're doing heapsort you might as well just collect the list into an array and do quicksort 😛

meager slate Nov 6, 2022, 2:34 PM

#

lol true

fiery cosmos Nov 6, 2022, 3:06 PM

#

is remembering the code of the linked list or query important?

agile sundial Nov 6, 2022, 3:17 PM

#

wdym query. generally you don't memorize code, just the ideas so that you can recreate it if necessary

fiery cosmos Nov 6, 2022, 6:07 PM

#

need help in #help-broccoli if anyone is around

fiery cosmos Nov 6, 2022, 6:24 PM

#

oh also i need help implementing the logic for removing items from my stack of free array index locations for a hashtable

#

any takers

haughty mountain Nov 6, 2022, 7:06 PM

#

fiery cosmos oh also i need help implementing the logic for removing items from my stack of f...

what does this even mean?

#

why not do like I suggested and read all the non-header strings first and then convert?

fiery cosmos Nov 6, 2022, 7:09 PM

#

pretty sure i got it. before i did not have the logic for removing an array index location from a free space stack after successful insertion for the chaining paradigm. eg, after successful insertion, i need to then go to my free space array and remove that location, so i don't select an occupied location and overwrite it

haughty mountain Nov 6, 2022, 7:10 PM

#

f.readline()  # skip header
strings = f.read().split()
# ...convert strings to int

haughty mountain Nov 6, 2022, 7:10 PM

#

fiery cosmos pretty sure i got it. before i did not have the logic for removing an array inde...

idk why you need that

#

don't you just pop from the stack when you actually need a new index?

fiery cosmos Nov 6, 2022, 7:11 PM

#

its mostly to fulfill a requirement of the assignment, "use a stack to keep track of free space." stack here is just a list i am modifying as i go

fiery cosmos Nov 6, 2022, 7:12 PM

#

haughty mountain ```py f.readline() # skip header strings = f.read().split() # ...convert string...

i'd be glad to implement this approach if i had more info. i don't think this is enough for me to figure out. i will try rn

haughty mountain Nov 6, 2022, 7:12 PM

#

fiery cosmos i'd be glad to implement this approach if i had more info. i don't think this is...

wdym?

#

just use readline to skip the first line

#

then read the rest and split on whitespace

fiery cosmos Nov 6, 2022, 7:13 PM

#

some inputs have headers that are like 4 lines, and others dont

haughty mountain Nov 6, 2022, 7:13 PM

#

and the headers have nothing in common, like some marker?

#

maybe post an example

fiery cosmos Nov 6, 2022, 7:14 PM

#

my inputs just begin with the data as integers. their input has some bullshit like:
`132.145 course name

required input

int1
int2
int3
...
`

#

i just need some conditionals within the try block, i think

#

to avoid headache i should just reformulate their required input lol

#

but they might test this w other files that are similar

haughty mountain Nov 6, 2022, 7:16 PM

#

is "required input" at the start of any input?

fiery cosmos Nov 6, 2022, 7:16 PM

#

technically yes, it'd be as above, where it is the last thing i'd read before the keys

#

wedged in there between the keys and the course number line

#

I could add that line to my inputs, to normalize things

#

then i could readline until i come across "Minimal required input:"

#

i think

#

what would that code look like

haughty mountain Nov 6, 2022, 7:20 PM

#

so...does the data have that line or not?

fiery cosmos Nov 6, 2022, 7:20 PM

#

their data does, my supplemental data does not, i could add it to make everything the same

#

i could add it to my inputs, yes

haughty mountain Nov 6, 2022, 7:21 PM

#

# Skip header
while True:
  if f.readline().strip() == 'required input':
    break

fiery cosmos Nov 6, 2022, 7:22 PM

#

i'll try this now, ty

haughty mountain Nov 6, 2022, 7:22 PM

#

err, maybe with a strip call

#

since readline includes the '\n'

#

edited

fiery cosmos Nov 6, 2022, 7:25 PM

#

uhh

#

?

#

i'm really bad at coding, remember

#

i'm pretty good w the logic but my programming is severely lacking

#

ok that's working so far

#

just have to catch strings while casting them to ints? but they are all strings rn

haughty mountain Nov 6, 2022, 7:29 PM

#

no

#

you don't need any loop over lines

fiery cosmos Nov 6, 2022, 7:30 PM

#

ok

haughty mountain Nov 6, 2022, 7:30 PM

#

and why do you do the readline after the while loop?

fiery cosmos Nov 6, 2022, 7:31 PM

#

i'd like you to assume that i am an extremely inexperienced programmer, and that any illogical series of things i post is due to lack of programmatic logic

#

i'm doing my best

#

ok so that is working to get all the keys

#

so during the process of casting them to int, i need to catch things that are alphabetic?

#

that's what i'm trying to do for error handling, anyhow

haughty mountain Nov 6, 2022, 7:32 PM

#

you can try-except that conversion

fiery cosmos Nov 6, 2022, 7:32 PM

#

ok ok on it

haughty mountain Nov 6, 2022, 7:33 PM

#

fiery cosmos i'm pretty good w the logic but my programming is severely lacking

it's more that I get the impression you're just throwing random stuff at the wall rather than thinking about what stuff does

fiery cosmos Nov 6, 2022, 7:33 PM

#

i am already in a while loop, so i do not need another for string in strings? or i do

fiery cosmos Nov 6, 2022, 7:34 PM

#

haughty mountain it's more that I get the impression you're just throwing random stuff at the wal...

there is a bit of this, and scatterbrained-ness, that's why i drink a pot of coffee every day

haughty mountain Nov 6, 2022, 7:36 PM

#

like, the thing you want to do can be broken down into a few steps

# Skip the header lines
...
# Read the rest of the entries as strings
...
# Convert the strings to int with the error checking
...

#

can you fill in the code for the first two ...?

fiery cosmos Nov 6, 2022, 7:39 PM

#

well i have both readline and read right now, and i don't know how they differ or can be used together, so i need to go read about that

haughty mountain Nov 6, 2022, 7:40 PM

#

readline reads the next line

fiery cosmos Nov 6, 2022, 7:40 PM

#

The read() will read the whole file at once and then print out the first characters that take up as many bytes as you specify in the parenthesis versus the readline() that will read and print out only the first characters that take up as many bytes as you specify in the parenthesis

haughty mountain Nov 6, 2022, 7:40 PM

#

read without arguments will read the rest of the file

fiery cosmos Nov 6, 2022, 7:46 PM

#

why would i want to break out of the while loop?

haughty mountain Nov 6, 2022, 7:48 PM

#

this tells me you don't really get the logic of what you're writing

fiery cosmos Nov 6, 2022, 7:48 PM

#

well we know that

haughty mountain Nov 6, 2022, 7:49 PM

#

haughty mountain like, the thing you want to do can be broken down into a few steps ```py # Skip ...

can you answer me this?

#

fill in the first ... part

#

we have a file object f

#

we want to skip past the header part

#

we already mentioned a way to detect the end of the header part before

fiery cosmos Nov 6, 2022, 7:51 PM

#

haughty mountain ```py # Skip header while True: if f.readline().strip() == 'required input': ...

this

haughty mountain Nov 6, 2022, 7:51 PM

#

yes

fiery cosmos Nov 6, 2022, 7:52 PM

#

why would you want to break out of the loop you're using to parse the file

haughty mountain Nov 6, 2022, 7:52 PM

#

that's not the loop to parse the file

fiery cosmos Nov 6, 2022, 7:52 PM

#

wouldn't you want a continue

#

oh

haughty mountain Nov 6, 2022, 7:52 PM

#

can you explain conceptually what the loop does?

fiery cosmos Nov 6, 2022, 7:53 PM

#

only that first bit. it's going to continue reading the file via f.readline until it comes across that condition

#

which we know will exist

haughty mountain Nov 6, 2022, 7:54 PM

#

so it reads until the line we know is at the end of the header

fiery cosmos Nov 6, 2022, 7:54 PM

#

correct

haughty mountain Nov 6, 2022, 7:54 PM

#

and then breaks the loop

fiery cosmos Nov 6, 2022, 7:54 PM

#

so we need to begin a new while loop?

haughty mountain Nov 6, 2022, 7:55 PM

#

you'll need to read the rest of the file somehow

#

but there are easier ways to get the strings you're after

fiery cosmos Nov 6, 2022, 7:56 PM

#

like read()

#

wait

#

indent is wrong

haughty mountain Nov 6, 2022, 7:58 PM

#

that's more sensible yes

#

note that rather than having 1 very complicated and error prone loop, this is 3 distinct and easy steps

fiery cosmos Nov 6, 2022, 7:59 PM

#

oohh could i print the string that was detected to output???

haughty mountain Nov 6, 2022, 7:59 PM

#

breaking a complicated problem into simpler parts is important

haughty mountain Nov 6, 2022, 7:59 PM

#

fiery cosmos oohh could i print the string that was detected to output???

wdym?

fiery cosmos Nov 6, 2022, 7:59 PM

#

like show the error i am catching

#

in a print

haughty mountain Nov 6, 2022, 8:00 PM

#

aren't you basically doing that already?

fiery cosmos Nov 6, 2022, 8:00 PM

#

oh i see how

#

duh

#

oh this thing does not have scope of the output

#

this is a separate function outside of main()

#

i'll have to return some things from this to main()

#

will this work?

#

its not coloring like it will

haughty mountain Nov 6, 2022, 8:03 PM

#

no reason for the second as

fiery cosmos Nov 6, 2022, 8:05 PM

#

i passed output to the getdata function

haughty mountain Nov 6, 2022, 8:05 PM

#

no need for args.output as output

fiery cosmos Nov 6, 2022, 8:06 PM

#

here it is now

haughty mountain Nov 6, 2022, 8:06 PM

#

why do you have the second thing in the with?

fiery cosmos Nov 6, 2022, 8:06 PM

#

oh its read by default huh

haughty mountain Nov 6, 2022, 8:06 PM

#

it's already an opened file

#

if you want to have the program exit if there is an error, why not just let an exception propagate through the program?

#

currently you catch an error, print as if you would stop the program, and then don't stop the program

fiery cosmos Nov 6, 2022, 8:08 PM

#

ok so i can remove my syntax after except ValueError and then add a try block to my main()

#

and catch it there

haughty mountain Nov 6, 2022, 8:08 PM

#

I wouldn't catch a ValueError in main

#

that can hide actual errors

fiery cosmos Nov 6, 2022, 8:08 PM

#

ok so what are you suggesting

haughty mountain Nov 6, 2022, 8:09 PM

#

you can throw your own exception

#

and only catch that

fiery cosmos Nov 6, 2022, 8:09 PM

#

ok

haughty mountain Nov 6, 2022, 8:09 PM

#

then you know that's from you explicitly throwing such an exception

fiery cosmos Nov 6, 2022, 8:10 PM

#

ah no i don't get it, they are all strings rn

haughty mountain Nov 6, 2022, 8:10 PM

#

wdym?

fiery cosmos Nov 6, 2022, 8:10 PM

#

wait maybe i do

#

like this: except "conversion to integer failed."?

haughty mountain Nov 6, 2022, 8:11 PM

#

no

fiery cosmos Nov 6, 2022, 8:11 PM

#

oof

haughty mountain Nov 6, 2022, 8:11 PM

#

you can create your own exception class easily

class MyException(Exception):
    pass

fiery cosmos Nov 6, 2022, 8:12 PM

#

outside of the getdata function?

haughty mountain Nov 6, 2022, 8:12 PM

#

why would you define the class inside?

fiery cosmos Nov 6, 2022, 8:12 PM

#

idk, that's why i'm asking 😂

#

why would i want an exception that just passes

#

exception is a weird word

#

exce

haughty mountain Nov 6, 2022, 8:14 PM

#

fiery cosmos why would i want an exception that just passes

it doesn't

#

the pass is just there since we don't define any methods or anything for the class

#

we can't just leave the body empty

#

because python

sweet viper Nov 6, 2022, 8:15 PM

#

Anyone knows good study material/vids for ppl leaning DSA?

haughty mountain Nov 6, 2022, 8:15 PM

#

MyException inherits from Exception, so it has all the members and functions Exception has

#

so you can then do

def f():
  try:
    something()
  except ValueError:
    raise MyException('something went wrong')

def main():
  try:
    f()
  except MyException as e:
    ...log e to file...

fiery cosmos Nov 6, 2022, 8:16 PM

#

sweet viper Anyone knows good study material/vids for ppl leaning DSA?

pins in this channel and youtube abdul bari

haughty mountain Nov 6, 2022, 8:16 PM

#

any exception not of type MyException will not be caught by the try in main

fiery cosmos Nov 6, 2022, 8:17 PM

#

i think you are overestimating my abilities here

haughty mountain Nov 6, 2022, 8:18 PM

#

maybe I shouldn't bother trying to suggest good ways of doing things 🤷‍♂️

#

exceptions is such a core part of python, you should really learn them

#

they can simplify flow like this a bunch

fiery cosmos Nov 6, 2022, 8:21 PM

#

what is the purpose of having your own exception class

haughty mountain Nov 6, 2022, 8:21 PM

#

have a guess

fiery cosmos Nov 6, 2022, 8:22 PM

#

for custom exceptions

#

like, non ValueError or non TypeError

#

stuff

#

custom errors*

haughty mountain Nov 6, 2022, 8:23 PM

#

what's bad about wrapping my whole code in

try:
  ...
except ValueError:
  ...

fiery cosmos Nov 6, 2022, 8:23 PM

#

bc ValueError could be many different things that may have gone wrong and its not explicit

haughty mountain Nov 6, 2022, 8:24 PM

#

yes, you will end up catching things you didn't intend to catch

#

and with your own exception class?

fiery cosmos Nov 6, 2022, 8:24 PM

#

you can make it very specific to a single error or type of error

haughty mountain Nov 6, 2022, 8:25 PM

#

fiery cosmos what is the purpose of having your own exception class

cool, that answers this

#

catching a generic error like ValueError is fine locally where you know what's going wrong

#

but having such a check globally will just end up hiding errors you didn't expect

#

better to have errors you don't explicitly handle terminate the program

#

that way coding errors will fail loudly rather than being silently ignored

haughty mountain Nov 6, 2022, 8:29 PM

#

haughty mountain so you can then do ```py def f(): try: something() except ValueError: ...

and even in my example here I would do

def main():
  try:
    f()
  except MyException as e:
    ...log e to file...
    raise e

#

so that the program terminates with a failure, and with the exception printed to the terminal

#

so you can have your logging layer, but better to re-raise the error

fiery cosmos Nov 6, 2022, 8:34 PM

#

alright let's try this bad boy

#

TypeError: catching classes that do not inherit from BaseException is not allowed

#

never seen this error before

#

ok this is what i have outside of main:

haughty mountain Nov 6, 2022, 8:39 PM

#

fiery cosmos `TypeError: catching classes that do not inherit from BaseException is not allow...

yes, you're not inheriting from Exception

fiery cosmos Nov 6, 2022, 8:40 PM

#

oh i need a return

haughty mountain Nov 6, 2022, 8:40 PM

#

also, name classes with capital letters

#

MyException

fiery cosmos Nov 6, 2022, 8:40 PM

#

gt it

#

got

haughty mountain Nov 6, 2022, 8:41 PM

#

haughty mountain also, name classes with capital letters

not an error, but lowercasing everything makes things hard to read

#

why do you implement logic in your class?

#

just inherit from Exception

fiery cosmos Nov 6, 2022, 8:43 PM

#

wdym

haughty mountain Nov 6, 2022, 8:45 PM

#

haughty mountain you can create your own exception class easily ```py class MyException(Exception...

this

haughty mountain Nov 6, 2022, 8:45 PM

#

haughty mountain `MyException` inherits from `Exception`, so it has all the members and functions...

this

#

what no

#

you define your own exception class

#

it doesn't need any additional logic than Exception has, it just needs to be its own type

#

then you can raise that exception just like you would any other

haughty mountain Nov 6, 2022, 8:50 PM

#

haughty mountain so you can then do ```py def f(): try: something() except ValueError: ...

example here

fiery cosmos Nov 6, 2022, 8:53 PM

#

that's what i was trying to do in the code i posted. i think i am not getting the inheritance thing

#

oh the inheritance is conferred by the raise keyword?

haughty mountain Nov 6, 2022, 8:57 PM

#

fiery cosmos oh the inheritance is conferred by the `raise` keyword?

no

#

class MyException(Exception):
    pass

fiery cosmos Nov 6, 2022, 8:57 PM

#

how does that class know its an error

#

or an exception

#

we just named it as such

haughty mountain Nov 6, 2022, 8:58 PM

#

MyException inherits from Exception

fiery cosmos Nov 6, 2022, 8:58 PM

#

oh oh oh i see

#

i thought Exception was a placeholder for the exception i caught

#

what if i want to pass along the string i found in the input?

#

with open(input) as f, output: AttributeError: __enter__

haughty mountain Nov 6, 2022, 9:05 PM

#

fiery cosmos what if i want to pass along the string i found in the input?

you can pass whatever string you want to the exception

haughty mountain Nov 6, 2022, 9:06 PM

#

fiery cosmos `with open(input) as f, output: AttributeError: __enter__`

just remove output

fiery cosmos Nov 6, 2022, 9:06 PM

#

that would require the class logic no?

haughty mountain Nov 6, 2022, 9:06 PM

#

no

#

Exception has that logic

#

(actually, maybe it's even BaseException, which Exception inherits from)

fiery cosmos Nov 6, 2022, 9:07 PM

#

where does it take it as argument

haughty mountain Nov 6, 2022, 9:07 PM

#

huh?

#

no

#

when you inherit from class you get access to all its functions and similar

#

Exception has an __init__ that takes a string

#

!e

class BaseClass:
  def f(self):
    print(42)

class DerivedClass(BaseClass):
  def g(self):
    print('hi')

x = DerivedClass()
x.f()
x.g()

x = BaseClass()
x.f()
x.g()  # does not work

halcyon plankBOT Nov 6, 2022, 9:10 PM

#

@haughty mountain :x: Your 3.11 eval job has completed with return code 1.

001 | 42
002 | hi
003 | 42
004 | Traceback (most recent call last):
005 |   File "<string>", line 15, in <module>
006 | AttributeError: 'BaseClass' object has no attribute 'g'

haughty mountain Nov 6, 2022, 9:10 PM

#

here you can see DerivedClass has access to both f and g

#

BaseClass only has f

fiery cosmos Nov 6, 2022, 9:11 PM

#

yeah what you wrote above makes total sense

#

so in my context, ValueError has access to the string which threw the error?

#

im not just seeing how to pass it along

#

the string which caused the ValueError

haughty mountain Nov 6, 2022, 9:13 PM

#

you have access to the variable with the string, no?

fiery cosmos Nov 6, 2022, 9:13 PM

#

there is no variable associated with it yet, it's just this:

#

probably should have included this:

haughty mountain Nov 6, 2022, 9:14 PM

#

string is the string that caused the error, no?

fiery cosmos Nov 6, 2022, 9:14 PM

#

yes

haughty mountain Nov 6, 2022, 9:14 PM

#

so what's the issue?

#

you probably want to add some formatting rather than just using the string as a message, but other than that you are using string as the message

fiery cosmos Nov 6, 2022, 9:15 PM

#

right i got you

#

wow this has been a long process to implement, but i learned a lot

haughty mountain Nov 6, 2022, 9:17 PM

#

I suspect you really want

except ValueError as e:
    raise Myexception(string) from e

#

otherwise you'll get some weird looking errors

fiery cosmos Nov 6, 2022, 9:19 PM

#

this works fine.. but you're saying not to use as such?

#

this is in my main block

haughty mountain Nov 6, 2022, 9:20 PM

#

!e I mean compare this error

def f():
  try:
    int('not valid')
  except ValueError:
    raise Exception('other exception')

f()

halcyon plankBOT Nov 6, 2022, 9:20 PM

#

@haughty mountain :x: Your 3.11 eval job has completed with return code 1.

001 | Traceback (most recent call last):
002 |   File "<string>", line 3, in f
003 | ValueError: invalid literal for int() with base 10: 'not valid'
004 | 
005 | During handling of the above exception, another exception occurred:
006 | 
007 | Traceback (most recent call last):
008 |   File "<string>", line 7, in <module>
009 |   File "<string>", line 5, in f
010 | Exception: other exception

haughty mountain Nov 6, 2022, 9:21 PM

#

!e to this

def f():
  try:
    int('not valid')
  except ValueError as e:
    raise Exception('other exception') from e

f()

halcyon plankBOT Nov 6, 2022, 9:21 PM

#

@haughty mountain :x: Your 3.11 eval job has completed with return code 1.

001 | Traceback (most recent call last):
002 |   File "<string>", line 3, in f
003 | ValueError: invalid literal for int() with base 10: 'not valid'
004 | 
005 | The above exception was the direct cause of the following exception:
006 | 
007 | Traceback (most recent call last):
008 |   File "<string>", line 7, in <module>
009 |   File "<string>", line 5, in f
010 | Exception: other exception

haughty mountain Nov 6, 2022, 9:22 PM

#

this is technically fine, but I would either call exit with a non-zero argument (which means an error)

#

or re-raise the exception

fiery cosmos Nov 6, 2022, 9:23 PM

#

ahh i see

haughty mountain Nov 6, 2022, 9:23 PM

#

i.e. you can do

    try:
        data = getdata(input, output)
    except Myexception as e:
        print(str(e) + ' was detected in the inputfile. Please check the inputfile and try again.', file = output)
        raise e

fiery cosmos Nov 6, 2022, 9:23 PM

#

it prints to console as well

#

exiting with non-zero error works fine too

#

oh wait nvm

haughty mountain Nov 6, 2022, 9:24 PM

#

exiting with non-zero at least signals something happens

fiery cosmos Nov 6, 2022, 9:24 PM

#

the output file is wrong

haughty mountain Nov 6, 2022, 9:24 PM

#

is it?

fiery cosmos Nov 6, 2022, 9:24 PM

#

wait wait

#

its never generating the outputfile

#

fuuu

haughty mountain Nov 6, 2022, 9:25 PM

#

re-raise the exception

#

then you can actually tell if that clause actually happens

#

(and this is why failing loudly is good)

fiery cosmos Nov 6, 2022, 9:26 PM

#

i think this not being in my context manager is causing issue

#

that clause isn't in my context manager because the for datum in data loop is also not

#

is that wrong

haughty mountain Nov 6, 2022, 9:28 PM

#

share the relevant code

#

without context that stuff just seems weird

#

seems like output is a string there, which would be weird

fiery cosmos Nov 6, 2022, 9:30 PM

#

https://pastebin.com/Bx0FLURQ

Pastebin

class Myexception(Exception): passdef getdata(input): out = [...

Pastebin.com is the number one paste tool since 2002. Pastebin is a website where you can store text online for a set period of time.

haughty mountain Nov 6, 2022, 9:31 PM

#

well yeah

#

output is string there

#

it's before you open the file

#

(and the naming doesn't exactly help)

fiery cosmos Nov 6, 2022, 9:33 PM

#

oh did i accidentally type it as string in argparse?

#

like should i remove that

haughty mountain Nov 6, 2022, 9:34 PM

#

it's not an issue with argparse

fiery cosmos Nov 6, 2022, 9:34 PM

#

the output should always be a named file keyed in at the command line

haughty mountain Nov 6, 2022, 9:35 PM

#

like, just think about it

#

in the print in the except

#

what is output?

fiery cosmos Nov 6, 2022, 9:36 PM

#

i thought it was the named text file, because just above i have
output = args.output

haughty mountain Nov 6, 2022, 9:36 PM

#

it's the name of a text file, sure

#

that's not what the file argument to print takes

fiery cosmos Nov 6, 2022, 9:37 PM

#

ok so this whole thing goes in its own context manager?

#

or i put it in the one i already have

#

the whole try block

haughty mountain Nov 6, 2022, 9:38 PM

#

you could put things inside the context manager, sure

#

granted, I would probably break your main function apart a bit, it's starting to get quite long

fiery cosmos Nov 6, 2022, 9:39 PM

#

bc the context manager comes after all of this

#

wait maybe not

#

maybe i could just put the try block? let me try 👀

#

nah that doesn't work

#

then data doesn't exist yet

#

weird it isn't exiting now

#

bruh. i am so bad at this

haughty mountain Nov 6, 2022, 9:47 PM

#

having the context manager wrap things wouldn't look so terrible if you only split things into functions

fiery cosmos Nov 6, 2022, 9:48 PM

#

would you mind deleting this and DMing me

haughty mountain Nov 6, 2022, 9:49 PM

#

why?

fiery cosmos Nov 6, 2022, 9:49 PM

#

so another student doesn't use it and make it look like we cheated or conspired or grabbed some random github code

#

if we turn in the same thing, one of us will be thought to be copying the other

haughty mountain Nov 6, 2022, 9:50 PM

#

you have the link already, right?

fiery cosmos Nov 6, 2022, 9:50 PM

#

yes

#

ty

#

and rather than use this verbatim, i will study the logic

#

i feel like i am getting pretty close with my impl

haughty mountain Nov 6, 2022, 9:51 PM

#

it's just extracting parts into functions

#

so the main function doesn't get huge

fiery cosmos Nov 6, 2022, 9:51 PM

#

that's fair enough

haughty mountain Nov 6, 2022, 9:52 PM

#

did you put this after the context manager or something?

fiery cosmos Nov 6, 2022, 9:52 PM

#

i put the try block in its own context manager

#

separate from the one that exists later to write to out

haughty mountain Nov 6, 2022, 9:53 PM

#

well yeah

fiery cosmos Nov 6, 2022, 9:54 PM

#

what did i do wrong

haughty mountain Nov 6, 2022, 9:54 PM

#

output is closed by the time you get to the except clause

#

because that's what context managers do

fiery cosmos Nov 6, 2022, 9:54 PM

#

getting rid of the close() gives the same error

haughty mountain Nov 6, 2022, 9:54 PM

#

do stuff when the block is exited

#

the close is irrelevant

fiery cosmos Nov 6, 2022, 9:55 PM

#

oh oh

haughty mountain Nov 6, 2022, 9:55 PM

#

you open the file with a context manager, that closes the file when the block is exited

fiery cosmos Nov 6, 2022, 9:55 PM

#

i see what's wrong ok

haughty mountain Nov 6, 2022, 9:56 PM

#

this will fail for other reasons

#

yes, that

fiery cosmos Nov 6, 2022, 9:57 PM

#

ok think i got it

haughty mountain Nov 6, 2022, 9:57 PM

#

open opens as 'r' by default

fiery cosmos Nov 6, 2022, 9:57 PM

#

yep

#

yeah i got it

#

and now it's writing to out. so now i have to test a non-error file

haughty mountain Nov 6, 2022, 9:57 PM

#

but at this point, you might as well put everything in one big with

fiery cosmos Nov 6, 2022, 9:57 PM

#

yep, it's working fine

haughty mountain Nov 6, 2022, 9:58 PM

#

and then if that feels messy break things into functions

fiery cosmos Nov 6, 2022, 9:58 PM

#

i could do that, eyah

#

yeah*

#

guess how many messages you've sent in here

#

that i return by searching for from: yourname

haughty mountain Nov 6, 2022, 9:59 PM

#

a lot

#

O(10k)?

fiery cosmos Nov 6, 2022, 10:00 PM

#

omega(10k)

haughty mountain Nov 6, 2022, 10:00 PM

#

right order of magnitude

fiery cosmos Nov 6, 2022, 10:00 PM

#

correct

#

ok im looking at your code now

haughty mountain Nov 6, 2022, 10:01 PM

#

in less than a year

fiery cosmos Nov 6, 2022, 10:01 PM

#

search goes back 1 year?

#

or you've been contributing for less than 1

haughty mountain Nov 6, 2022, 10:01 PM

#

I've been in this server since december last year

fiery cosmos Nov 6, 2022, 10:01 PM

#

ah i see

#

do you like trivia?

#

i like trivia regarding large numbers. like random facts

#

its kind of remarkable you're able to go through and clean up code in the way you do. i guess you have a lot of practice

#

american lottery is up to US $1.9b.. 👀

opal oriole Nov 6, 2022, 10:05 PM

#

cold bluff yea is in there

You probably want (Euclidean) geometry, and algebra. Khan has courses for both.

haughty mountain Nov 6, 2022, 10:06 PM

#

fiery cosmos its kind of remarkable you're able to go through and clean up code in the way yo...

I feel like everyone has the reaction "I kinda hate your code, I feel like I know better how it should look like" when seeing most other people's code

#

but yes, I've coded a lot, so doing small refactoring is kinda second nature

fiery cosmos Nov 6, 2022, 10:07 PM

#

but then your default mindset is that of hatred. maybe you just see things for what they could be. an eternal optimist

#

i guess its the same with anything, when people get good at it.

#

eg, some pro golfer seeing someone else's swing and being like "this is crap and here is why and here is how you fix it"

haughty mountain Nov 6, 2022, 10:09 PM

#

eternal optimist feels like it misses the mark 😛

opal oriole Nov 6, 2022, 10:09 PM

#

When working in a team an important thing to do is to realize that others will code in different ways and you kind of just have to let them, or go insane trying to correct them on everything.

haughty mountain Nov 6, 2022, 10:09 PM

#

I have opinions on roughly what I think good code should look like

fiery cosmos Nov 6, 2022, 10:10 PM

#

oh i know lol i am painting it in a better light 😂

haughty mountain Nov 6, 2022, 10:10 PM

#

opal oriole When working in a team an important thing to do is to realize that others will c...

to some extent

fiery cosmos Nov 6, 2022, 10:10 PM

#

@opal oriole are you in charge of software devs?

opal oriole Nov 6, 2022, 10:10 PM

#

You can ofc have them run their code through a tool.

haughty mountain Nov 6, 2022, 10:10 PM

#

sometimes you should intervene in code reviews and say that the thing could be a lot cleaner if written differently

fiery cosmos Nov 6, 2022, 10:11 PM

#

how do y'all feel about these coding tools like where AI will partially write something or auto-suggest

opal oriole Nov 6, 2022, 10:11 PM

#

Yeah, but it's a balance, do it too much and it creates conflict.

haughty mountain Nov 6, 2022, 10:11 PM

#

like, I've had colleagues code that I genuinely didn't understand until I went through and re-wrote it

#

because it was a real mess of conditional logic

#

which could have been refactored into something way clearer

opal oriole Nov 6, 2022, 10:12 PM

#

fiery cosmos how do y'all feel about these coding tools like where AI will partially write so...

It's fine in concept, but legally, not so much.

haughty mountain Nov 6, 2022, 10:12 PM

#

if I can easily understand the code easily I rarely have strong opinions, unless it's doing something very silly

opal oriole Nov 6, 2022, 10:12 PM

#

It's weird grey area that stuff.

opal oriole Nov 6, 2022, 10:13 PM

#

haughty mountain if I can easily understand the code easily I rarely have strong opinions, unless...

Pretty much the idea, it's important to check oneself though, not bordering on OCD.

haughty mountain Nov 6, 2022, 10:14 PM

#

I'll be OCD about it only if you break our style guide 😛

#

outside that lies nuance

opal oriole Nov 6, 2022, 10:14 PM

#

Yeah run through the tools.

haughty mountain Nov 6, 2022, 10:14 PM

#

style guide is not only tooling though

opal oriole Nov 6, 2022, 10:14 PM

#

Then it's just the process and not so much personal conflict.

haughty mountain Nov 6, 2022, 10:15 PM

#

naming schemes, naming standards, restrictions on how you write stuff to keep things sane

opal oriole Nov 6, 2022, 10:16 PM

#

Some things still require humans to look at it, but what is important is that the rules are written.

stable pecan Nov 6, 2022, 10:18 PM

#

@sweet roost , @hearty python I had to go, but I thought yall would enjoy another way to parse lists:

def parse(text):
    tokens = iter(
        text
        .replace(",", " ")
        .replace("[", " [ ")
        .replace("]", " ] ")
        .split()
    )

    def _parse():
        for token in tokens:
            if token == "[":
                yield list(_parse())
            elif token == "]":
                return
            else:
                yield int(token)

    return next(_parse())

Both linear and recursive!

haughty mountain Nov 6, 2022, 10:18 PM

#

opal oriole Some things still require humans to look at it, but what is important is that th...

as an example, google's style guide for python
https://google.github.io/styleguide/pyguide.html

styleguide

Style guides for Google-originated open-source projects

#

they list not only what the rules are, but the motivation behind them

#

so even if you disagree with some choice there is motivation behind the choice

#

(and if you really feel like it's wrong you can try to work to change the style guide by giving some motivation to the contrary)

#

it makes the style guide very long though 😛

opal oriole Nov 6, 2022, 10:21 PM

#

haughty mountain as an example, google's style guide for python https://google.github.io/stylegui...

Yeah, a written record of the changes and why is good.

#

It does take more work though.

haughty mountain Nov 6, 2022, 10:21 PM

#

and the google python guideline is still short compared to their C++ one

#

the C++ one has almost 30k words

#

the python one 12k

haughty mountain Nov 6, 2022, 10:22 PM

#

opal oriole It does take more work though.

yeah, maintaining your own style guide only makes sense if your company is big enough

#

to warrant that extra cost

opal oriole Nov 6, 2022, 10:23 PM

#

Otherwise, copy what you see already is generally the rule.

haughty mountain Nov 6, 2022, 10:23 PM

#

which works great if everyone was a good programmer 😛

#

actually, even with good programmers you have diverging styles

opal oriole Nov 6, 2022, 10:24 PM

#

(And a big company will have varying skill levels)

fiery cosmos Nov 6, 2022, 10:25 PM

#

i probably brought this up before, but do you all think anyone can code or it requires a certain type of thinking that is less learnable? like super left brained or whatever (if thats a real thing). could some masterful artist learn to code?

haughty mountain Nov 6, 2022, 10:26 PM

#

I think "anyone can code" is true at some basic level, but I don't think everyone has the capability of being a great programmer

#

people are quite different

opal oriole Nov 6, 2022, 10:27 PM

#

Somewhat touchy topic. IMO anyone, and the reason why some seem to not be able is due to various other factors (their life situation).

haughty mountain Nov 6, 2022, 10:27 PM

#

"anyone" encompasses a lot

opal oriole Nov 6, 2022, 10:27 PM

#

Probably the most important thing is just interest though.

haughty mountain Nov 6, 2022, 10:29 PM

#

opal oriole Somewhat touchy topic. IMO anyone, and the reason why some seem to not be able i...

nature and nurture

fiery cosmos Nov 6, 2022, 10:29 PM

#

i don't think it needs to be a touchy subject. it's just a matter of inherent giftedness toward a particular topic. you'd probably not take a masterful programmer and make them some elite artist, as an example

#

yeah its just nature v nurture

haughty mountain Nov 6, 2022, 10:29 PM

#

haughty mountain nature and nurture

you kinda need both to be "great"

opal oriole Nov 6, 2022, 10:29 PM

#

haughty mountain nature and nurture

Yeah and I think nature is pretty solid on average, humans are smart.

fiery cosmos Nov 6, 2022, 10:30 PM

#

opal oriole Yeah and I think nature is pretty solid on average, humans are smart.

i feel this way as well about people

opal oriole Nov 6, 2022, 10:30 PM

#

But not much can be done if i'm born in a place without food, let alone a computer.

fiery cosmos Nov 6, 2022, 10:30 PM

#

many brilliant people everywhere

#

of course

haughty mountain Nov 6, 2022, 10:30 PM

#

opal oriole Yeah and I think nature is pretty solid on average, humans are smart.

the "average" part is very important there

fiery cosmos Nov 6, 2022, 10:31 PM

#

https://en.wikipedia.org/wiki/Normal_distribution

Normal distribution

In statistics, a normal distribution or Gaussian distribution is a type of continuous probability distribution for a real-valued random variable. The general form of its probability density function is

...

haughty mountain Nov 6, 2022, 10:31 PM

#

your average person being capable doesn't mean everyone is

fiery cosmos Nov 6, 2022, 10:31 PM

#

of course

haughty mountain Nov 6, 2022, 10:31 PM

#

I think the average person can learn to become a decent programmer, for sure

fiery cosmos Nov 6, 2022, 10:32 PM

#

what separates a decent programmer from an elite one

haughty mountain Nov 6, 2022, 10:32 PM

#

I just don't like the "anyone" framing because there are always outliers

haughty mountain Nov 6, 2022, 10:36 PM

#

fiery cosmos what separates a decent programmer from an elite one

err, I feel that's a "I know it when I see it" kind of thing

fiery cosmos Nov 6, 2022, 10:36 PM

#

fair enough

haughty mountain Nov 6, 2022, 10:36 PM

#

like, I do interviewing for my company, you can easily tell when people really know their stuff

fiery cosmos Nov 6, 2022, 10:36 PM

#

like an example would be someone who wrote a great program or platform or app or something?

fiery cosmos Nov 6, 2022, 10:37 PM

#

haughty mountain like, I do interviewing for my company, you can easily tell when people really k...

it was the same for me in biotech. surprisingly, most of them failed my easy question

haughty mountain Nov 6, 2022, 10:38 PM

#

I know google has numbers for number of applications, let me find them

fiery cosmos Nov 6, 2022, 10:39 PM

#

one of those big techs puts a 6 month cooldown on you if you fail their interview

haughty mountain Nov 6, 2022, 10:39 PM

#

so this is from a few years back, they got ~3 million applications in a year

fiery cosmos Nov 6, 2022, 10:39 PM

#

can you believe apple is now worth more than alphabet, meta, amzn, and another big tech combined??

fiery cosmos Nov 6, 2022, 10:39 PM

#

haughty mountain so this is from a few years back, they got ~3 million applications in a year

jesus

haughty mountain Nov 6, 2022, 10:40 PM

#

and the acceptance rate is stated as 0.2%

fiery cosmos Nov 6, 2022, 10:40 PM

#

im surprised amzn isn't more profitable, they also deal in software

#

that's insane

haughty mountain Nov 6, 2022, 10:40 PM

#

that's still 6k people

opal oriole Nov 6, 2022, 10:40 PM

#

Big companies get spammed.

#

Which is really annoying for those that know their stuff.

fiery cosmos Nov 6, 2022, 10:41 PM

#

they have among the best percs though, so there is good reason. if you work at google and die your children get your salary until they turn 18

haughty mountain Nov 6, 2022, 10:41 PM

#

so order of magnitude thinking, 1/1000 gets hired, google has ~3 stages

#

CV screening (I'm guessing probably only 1/100 gets through that, it's very aggressive)

fiery cosmos Nov 6, 2022, 10:42 PM

#

CV screening is automated?

haughty mountain Nov 6, 2022, 10:42 PM

#

phone interview (let's assume 1/10 gets through)
full interview (probably another 1/10)

fiery cosmos Nov 6, 2022, 10:43 PM

#

are you tooting your own horn rn

haughty mountain Nov 6, 2022, 10:43 PM

#

the distribution is probably a bit different, but it feels about right

#

I'm just trying to put that number into context

#

many stages, pretty aggressive culling in each

fiery cosmos Nov 6, 2022, 10:44 PM

#

well, lots of companies need programmers, even if they are mediocre

haughty mountain Nov 6, 2022, 10:44 PM

#

I have no clue how CV screening works at google, part of it is probably automated

fiery cosmos Nov 6, 2022, 10:44 PM

#

data science to enable higher sales isn't exactly product breaking

haughty mountain Nov 6, 2022, 10:44 PM

#

considering 3M of them

fiery cosmos Nov 6, 2022, 10:44 PM

#

data science at a tent selling company

haughty mountain Nov 6, 2022, 10:46 PM

#

realistically the CV screening is probably more aggressive than 1/100 pithink

#

since anything after that point will involve a lot of costs

fiery cosmos Nov 6, 2022, 10:47 PM

#

alright heres my CV: do i get through?

knows good stuff and such, and is a very stand-up individual

#

hired ✅

#

do you know the "you're hired" trick?

haughty mountain Nov 6, 2022, 10:48 PM

#

my CV is terrible looking and breaks so many "rules" people say you should follow

opal oriole Nov 6, 2022, 10:48 PM

#

Automated screen is most likely keyword based.

#

(Some people tried just spamming keywords and it works)

haughty mountain Nov 6, 2022, 10:48 PM

#

thankfully I haven't had to go through a CV screening process

#

it's always been recruiters reaching out to me

fiery cosmos Nov 6, 2022, 10:48 PM

#

opal oriole Automated screen is most likely keyword based.

ah man, i'm gonna need more python's and numpy's in there

opal oriole Nov 6, 2022, 10:49 PM

#

In smaller companies it can often be someone reaching out to you too.

#

Especially if you have been posting things.

#

Doing your own interesting stuff.

fiery cosmos Nov 6, 2022, 10:49 PM

#

the hired trick is this:

interviewer: "hello, what is your name?"

interveiwee: "hired."

interviewer: "you're hired?"

interveiwee: "great. see you Monday!"

#

ᶦ'ˡˡ ˢᵉᵉ ᵐʸˢᵉˡᶠ ᵒᵘᵗ

#

oh one more question

#

when trying to remove list indices from my stack

haughty mountain Nov 6, 2022, 10:57 PM

#

wait what are you trying to do?

fiery cosmos Nov 6, 2022, 10:57 PM

#

i was unexpectedly getting p is not in list

haughty mountain Nov 6, 2022, 10:57 PM

#

calling remove is a big red flag to me

fiery cosmos Nov 6, 2022, 10:57 PM

#

i'm trying to go and remove that array location to make the stack of free elements accurate

#

i have some degree of confidence it works, because i am inserting all the keys in my test case. let me try a larger input..

haughty mountain Nov 6, 2022, 10:59 PM

#

why do you need to remove the array location?

fiery cosmos Nov 6, 2022, 10:59 PM

#

oh no

haughty mountain Nov 6, 2022, 10:59 PM

#

like you know when you need to add a new node

fiery cosmos Nov 6, 2022, 10:59 PM

#

i just tried an execution and entered a forever loop 😭

#

ok so a smaller input size worked, keys = 36

haughty mountain Nov 6, 2022, 11:00 PM

#

what's that code even doing?

fiery cosmos Nov 6, 2022, 11:00 PM

#

stack is a list of bucket locations

haughty mountain Nov 6, 2022, 11:00 PM

#

you try to insert at p (the primary hash) self.tablesize times?

fiery cosmos Nov 6, 2022, 11:01 PM

#

sorry that's not the whole snippet

#

1s

#

oh duh

#

it only failed bc i didn't update my headers

haughty mountain Nov 6, 2022, 11:02 PM

#

why do you need the remove?

#

also, don't do this self.stack.pop(0)

fiery cosmos Nov 6, 2022, 11:03 PM

#

bc they want that "stack" to represent the free bucket locations

haughty mountain Nov 6, 2022, 11:03 PM

#

unless you decided to use a deque for some reason

fiery cosmos Nov 6, 2022, 11:03 PM

#

no, i still have a list named stack

fiery cosmos Nov 6, 2022, 11:03 PM

#

haughty mountain also, don't do this `self.stack.pop(0)`

why?

#

output looks fine

haughty mountain Nov 6, 2022, 11:04 PM

#

it's O(n)

fiery cosmos Nov 6, 2022, 11:04 PM

#

this was for k = 84 keys

haughty mountain Nov 6, 2022, 11:04 PM

#

correctness isn't the issue

fiery cosmos Nov 6, 2022, 11:04 PM

#

and chaining

haughty mountain Nov 6, 2022, 11:04 PM

#

it's just super dumb from a performance point

fiery cosmos Nov 6, 2022, 11:04 PM

#

is there a better way to pop from front?

haughty mountain Nov 6, 2022, 11:04 PM

#

pop() which pops from the end is O(1)

#

why do you want to pop from the front?

#

if you pop from the front and insert in the back it's not a stack even

fiery cosmos Nov 6, 2022, 11:05 PM

#

no i'm aware. there is no insertion

haughty mountain Nov 6, 2022, 11:06 PM

#

if you just want to start picking low indices start with it being a reversed range

#

and pop from the end

fiery cosmos Nov 6, 2022, 11:06 PM

#

ohh

#

right ok

haughty mountain Nov 6, 2022, 11:07 PM

#

granted, you are dealing with so small tables basically nothing matters performance wise

#

which kinda sucks

fiery cosmos Nov 6, 2022, 11:07 PM

#

it's ok, i know why is it wrong

haughty mountain Nov 6, 2022, 11:07 PM

#

but going back to this, why would you remove?

fiery cosmos Nov 6, 2022, 11:08 PM

#

i wonder if popping from the back would place things outside the artifical modulo constraint?

#

or sorry

#

popping the highest index first

fiery cosmos Nov 6, 2022, 11:08 PM

#

haughty mountain but going back to this, why would you `remove`?

so i am guaranteed not to pull that same index again

fiery cosmos Nov 6, 2022, 11:10 PM

#

fiery cosmos i wonder if popping from the back would place things outside the artifical modul...

yeah, it does

haughty mountain Nov 6, 2022, 11:10 PM

#

oh, because the first position is special

#

well, that sucks

haughty mountain Nov 6, 2022, 11:11 PM

#

fiery cosmos i wonder if popping from the back would place things outside the artifical modul...

what, how?

fiery cosmos Nov 6, 2022, 11:11 PM

#

haughty mountain what, how?

only for chaining. there is no probe computation

#

i could make the stack only up the the modulo integer..

haughty mountain Nov 6, 2022, 11:11 PM

#

fiery cosmos i wonder if popping from the back would place things outside the artifical modul...

oh, because you add table_size elements to the stack

fiery cosmos Nov 6, 2022, 11:12 PM

#

right

haughty mountain Nov 6, 2022, 11:12 PM

#

rather than the actually usable ones

#

again, this thing is immensely broken

fiery cosmos Nov 6, 2022, 11:12 PM

#

they "become" usable

#

i am aware, don't remind me

#

had a total meltdown last night over it

haughty mountain Nov 6, 2022, 11:13 PM

#

doing hacks that shouldn't be needed to accommodate their terrible choice isn't a great idea

#

it only makes things more confusing

fiery cosmos Nov 6, 2022, 11:14 PM

#

i just wonder if i should let the thing 'overflow' into using the indices beyond the modulo constraint

#

or just only make the stack elements up to that

haughty mountain Nov 6, 2022, 11:14 PM

#

haughty mountain oh, because the first position is special

so, I see why you need to special case the primary hash, but that's pretty terrible

fiery cosmos Nov 6, 2022, 11:14 PM

#

correct

#

i've tried debating w prof over this for hours, she does not understand how its supposed to work

#

its painfully obvious

haughty mountain Nov 6, 2022, 11:15 PM

#

an O(n) cost for every insertion

fiery cosmos Nov 6, 2022, 11:15 PM

#

haughty mountain an O(n) cost for every insertion

huh

haughty mountain Nov 6, 2022, 11:15 PM

#

remove is O(n)

#

actually, I feel you can solve this nicer

#

instead of doing the remove, why not, when getting a new bucket, pop until you get a bucket that you know is free?

opal oriole Nov 6, 2022, 11:17 PM

#

haughty mountain doing hacks that shouldn't be needed to accommodate their terrible choice isn't ...

This is something I have run into before, where I have some idea in my head of how this kind of thing is normally done, but then they need some weird requirements which trips me up. I have to kind of clear my mind and assume that it's all broken.

haughty mountain Nov 6, 2022, 11:17 PM

#

given an index you could pretty easily check if the bucket is empty

fiery cosmos Nov 6, 2022, 11:18 PM

#

uhh right now i have bigger fish to fry, i'm getting IndexError: pop from empty list

#

that is, of course, when i try an input that is one too big for the tablesize

#

i tried key = 121, tablesize 120

#

buckets size 1

#

i was just making sure my error checking still worked, it does not

haughty mountain Nov 6, 2022, 11:20 PM

#

wait, the chained one is the one exception where you can actually use all the buckets

fiery cosmos Nov 6, 2022, 11:20 PM

#

haughty mountain instead of doing the remove, why not, when getting a new bucket, pop until you g...

by virtue of it being in the list, it is free. as long as i remove while inserting

fiery cosmos Nov 6, 2022, 11:21 PM

#

haughty mountain wait, the chained one is the one exception where you can actually use all the bu...

yes

haughty mountain Nov 6, 2022, 11:21 PM

#

fiery cosmos by virtue of it being in the list, it is free. as long as i remove while inserti...

yes, that removal is very expensive

fiery cosmos Nov 6, 2022, 11:21 PM

#

no i get that, but can we first solve my error

#

line 131, in chaininsert new_p = self.stack.pop() IndexError: pop from empty list

#

so weird

#

keep in mind, this is only for when there are too many keys to fit in the table

#

lms where i thought i was catching that

haughty mountain Nov 6, 2022, 11:23 PM

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so you're inserting the 121th key and it fails?

fiery cosmos Nov 6, 2022, 11:23 PM

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ah i think i've got it. i had the error catching in one prog and not the other

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CRAP

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i got it working to catch the error but now it's not working for legitimate input. everything beneath my first context man is greyed out. 1s

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is there some proper way to close a context manager maybe i dont know about?

haughty mountain Nov 6, 2022, 11:32 PM

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huh?

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what are you even doing?

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the point of context managers are that they handle resources

fiery cosmos Nov 6, 2022, 11:32 PM

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i put my error catching logic in the same with open as the one we just developed

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and it worked great, but now the code is never running past it, as i can tell from everything being greyed out

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am i maybe missing a continue or pass or break or close() or something

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i tried like output.close(), close(output) etc

haughty mountain Nov 6, 2022, 11:34 PM

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why would you need to close it?

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that's the point of the context manager

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that you don't need to

fiery cosmos Nov 6, 2022, 11:34 PM

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i have two separate ones

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this is the one above the rest of my logic

haughty mountain Nov 6, 2022, 11:34 PM

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I can't help much without the code...

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other than making dumb guesses

fiery cosmos Nov 6, 2022, 11:34 PM

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i'll pastebin

haughty mountain Nov 6, 2022, 11:35 PM

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it's clearly either some infinite loop or you unconditionally exiting in some way

fiery cosmos Nov 6, 2022, 11:36 PM

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dm'd

haughty mountain Nov 6, 2022, 11:36 PM

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err

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yes, it exits

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just like you explicitly told it to

fiery cosmos Nov 6, 2022, 11:37 PM

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o m g

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thank you

haughty mountain Nov 6, 2022, 11:37 PM

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haughty mountain it's clearly either some infinite loop or you unconditionally exiting in some wa...

so option number 2

fiery cosmos Nov 6, 2022, 11:38 PM

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hmm so i am printing but also throwing a command line error

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what if you want to avoid command line errors from displaying?

haughty mountain Nov 6, 2022, 11:38 PM

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in what case?

fiery cosmos Nov 6, 2022, 11:39 PM

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so i'm not showing that ugly pop from empty list error

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in the case that the keys > tablesize

haughty mountain Nov 6, 2022, 11:40 PM

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that's an error in your code, no

fiery cosmos Nov 6, 2022, 11:40 PM

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yes

haughty mountain Nov 6, 2022, 11:41 PM

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why wouldn't you want that shown?

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fail loudly

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so you can fix it

fiery cosmos Nov 6, 2022, 11:41 PM

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fair enough. i just feel like its cleaner if it runs successfully and they check the output and see the error message

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rather than both

haughty mountain Nov 6, 2022, 11:42 PM

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if anything, the command line is the place where errors for sure should go

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maybe with a copy also logged to file

fiery cosmos Nov 6, 2022, 11:43 PM

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i'll just leave it, i've already spent way too much time on this today. i just need to be sure the core functionality is up and running

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also i have not yet eaten and its 7:00pm

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so, i need to do that.

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ah crap

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it doesn't work for the tablesize = 40 and bucketsize 3 case. let me check

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so weird

haughty mountain Nov 6, 2022, 11:45 PM

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linearinsert and quadinsert being basically copies of each other is...not great

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they have one difference which probably is a bug

fiery cosmos Nov 6, 2022, 11:46 PM

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i don't understand why this isn't working for the tablesize = 40 and bucketsize = 3 case

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i'm computing the size of the table as (hashtable.tablesize*hashtable.bucketsize)

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think i got it

haughty mountain Nov 6, 2022, 11:49 PM

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btw, your linearinsert and quadinsert code doesn't make sense to me

fiery cosmos Nov 6, 2022, 11:49 PM

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ok we're good

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how so

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brb

haughty mountain Nov 6, 2022, 11:49 PM

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why do you have like 4 calls to try_insert in it

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in a sane world the whole linear insert loop is

h = primary_hash(key, self.primary_hash_int)
for i in range(self.tablesize):
  j = (h + i) % self.table_size
  if self.table[j].try_insert(key):
    self.count += 1
    break
```minor difference in the bad reality, different mod and a terrible if check

fiery cosmos Nov 6, 2022, 11:58 PM

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does this first try the initial hash location when i = 0?

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you have to try the primary hash location first, before computing a probe

haughty mountain Nov 6, 2022, 11:59 PM

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h + 0 is h yes

fiery cosmos Nov 6, 2022, 11:59 PM

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probing is to resolve a collision

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but then i am modding by primary_hash_int again

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i just dont know if that'll first check the h location

haughty mountain Nov 7, 2022, 12:01 AM

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x % m % m is the same as x % m

fiery cosmos Nov 7, 2022, 12:01 AM

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ok

haughty mountain Nov 7, 2022, 12:01 AM

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do you know what the mod operation does?

fiery cosmos Nov 7, 2022, 12:02 AM

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returns the remainder after dividing the two numbers

haughty mountain Nov 7, 2022, 12:03 AM

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well yeah

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but it puts the number in the range [0, m)

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by adding/subtracting a multiple of m to put it in that range

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if you're already in that range, nothing happens

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hence why modding twice doesn't change anything

fiery cosmos Nov 7, 2022, 12:05 AM

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can i ask you something

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how does the chaining ever get like a pointer to an empty location

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i feel like that'll never happen

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oh i does when we pop from the stack

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but when we first arrive at a bucket, it'll never have a pointer to an open location

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so why are we checking that

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why are we following that and trying to insert rather

haughty mountain Nov 7, 2022, 12:08 AM

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pithink

fiery cosmos Nov 7, 2022, 12:08 AM

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haughty mountain in a sane world the whole linear insert loop is ```py h = primary_hash(key, self...

i'm trying to implement this now without screwing up my if h is outside the table check

haughty mountain Nov 7, 2022, 12:10 AM

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fiery cosmos why are we following that and trying to insert rather

the logic is just

can I insert here? if so I'm done
otherwise is there a link to follow, if so follow it
otherwise we need a new bucket, link to a new empty bucket and follow the link
go to 1.

fiery cosmos Nov 7, 2022, 12:11 AM

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i don't see any chains every occurring though

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i don't think we'll ever arrive at a bucket that has a pointer. the only pointing we do is instant during our stack pop

haughty mountain Nov 7, 2022, 12:12 AM

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fiery cosmos i don't see any chains every occurring though

wdym?

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we assign pointers when we add buckets

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if you have a collision you'll follow the link

fiery cosmos Nov 7, 2022, 12:14 AM

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i can't see it, i could be wrong

haughty mountain Nov 7, 2022, 12:14 AM

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can't see it how?

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in the table data?

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in the code logic?

fiery cosmos Nov 7, 2022, 12:14 AM

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i cannot see it in the logic, yes. i'll check again

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i just feel that when we first arrive to a bucket, it'll never point to an empty bucket. maybe that isn't the point. the point is so that we can follow the chain for lookups

haughty mountain Nov 7, 2022, 12:16 AM

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it's more relevant when doing lookups for sure

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in insertion it's just the terminating case

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though it catches both the first insertion (primary bucket is empty)

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and the insertion when we need to add a bucket

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no need for the first if

fiery cosmos Nov 7, 2022, 12:17 AM

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i need it, there is a tablesize = 40 and modulo 41 case

haughty mountain Nov 7, 2022, 12:18 AM

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you don't need the first if

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second sure, because of that case

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but not the first one

fiery cosmos Nov 7, 2022, 12:18 AM

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how

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like, why can't we get something beyond the tablesize in that scenario

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cause it'll mod to 40 in the highest case?

haughty mountain Nov 7, 2022, 12:19 AM

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why would the first if matter for anything?

fiery cosmos Nov 7, 2022, 12:20 AM

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if h(key) = 41

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and tablesize is 40

haughty mountain Nov 7, 2022, 12:20 AM

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ok

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walk through that case in the code

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in your head

fiery cosmos Nov 7, 2022, 12:21 AM

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oh

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h gets set equal to j

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ok

haughty mountain Nov 7, 2022, 12:21 AM

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other way around

fiery cosmos Nov 7, 2022, 12:22 AM

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right right

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so i can use the same clause for quadinsert

haughty mountain Nov 7, 2022, 12:22 AM

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the only difference between those two is the probing

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you could re-use the same code for both

fiery cosmos Nov 7, 2022, 12:22 AM

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right

haughty mountain Nov 7, 2022, 12:23 AM

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(h + probing_fun(i)) % mod

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where probing_fun(i) is i for the linear case and i*(i+1)//2 for the quadratic case

fiery cosmos Nov 7, 2022, 12:24 AM

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i'm moving slow bc i am updating two different scripts

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right, you pointed that out before i recall

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interesting that there is a case where we can go past the modulo constraint with chaining

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i guess its "less broken"? idk

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still, load factors have been a headache

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i just calculate both

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tysm for your help!!!!!!!!!!

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huh. its no longer printing that stack error

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ooh that was only for chaining, i am running quad probing nvm

haughty mountain Nov 7, 2022, 12:29 AM

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fiery cosmos i guess its "less broken"? idk

slightly

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the primary hash mod is still dumb

fiery cosmos Nov 7, 2022, 12:29 AM

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i still wonder if they want to overflow into that area, i will ask

fiery cosmos Nov 7, 2022, 12:30 AM

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haughty mountain the primary hash mod is still dumb

oh its horrific

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i totally did not have a full meltdown over this

haughty mountain Nov 7, 2022, 12:30 AM

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the only way to get to the extra few buckets is chaining

fiery cosmos Nov 7, 2022, 12:32 AM

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right. at least there is that. but like, the notion of creating a bigger table is totally out the window w linear and quad

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doesn't matter if you make a bigger table or not 😂

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i know you still don't like that O(n) insert, i can fix that before due date

haughty mountain Nov 7, 2022, 12:44 AM

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fiery cosmos i know you still don't like that O(n) insert, i can fix that before due date

you just have to modify the way you get an empty bucket

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you can easily check if a bucket is empty, right?

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so you can pop until you actually get an empty bucket

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that removes the need for the .remove

fiery cosmos Nov 7, 2022, 12:45 AM

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i would need the remove afterward though no?

haughty mountain Nov 7, 2022, 12:45 AM

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so the stack contains potentially empty buckets

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you wouldn't need to

fiery cosmos Nov 7, 2022, 12:46 AM

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its supposed to keep track of the free space, not the potentially free space

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but yeah, its a great point considering the whole point of a hashtable is those O(1) operations..

haughty mountain Nov 7, 2022, 12:47 AM

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I don't know of a way to keep a stack of free buckets that allows removals like the ones you would need

fiery cosmos Nov 7, 2022, 12:48 AM

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maybe a deque?

haughty mountain Nov 7, 2022, 12:48 AM

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without getting these expensive removal costs

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why would that help for removal?

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you still need to find the element to remove

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which is O(n)

fiery cosmos Nov 7, 2022, 12:49 AM

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i think list lookups are O(1) and linear search is O(n)?

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oh i see why

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bc im not removing by index, im literally finding and removing the element

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ok ok

haughty mountain Nov 7, 2022, 12:50 AM

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removing by index would be O(n) for deque too

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deque is basically a linked list complexity-wise

fiery cosmos Nov 7, 2022, 12:51 AM

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removing by index is O(n) for a list?

haughty mountain Nov 7, 2022, 12:51 AM

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even indexing is O(n) for a ~~list~~ deque

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well

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O(distance from either end to the index)

fiery cosmos Nov 7, 2022, 12:51 AM

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right ok

haughty mountain Nov 7, 2022, 12:51 AM

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err

fiery cosmos Nov 7, 2022, 12:51 AM

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but then wouldn't hash tables not be as fast?

haughty mountain Nov 7, 2022, 12:51 AM

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deque, not list

fiery cosmos Nov 7, 2022, 12:52 AM

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we're doing the same thing w a hashtable (indexing into the array)

haughty mountain Nov 7, 2022, 12:52 AM

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indexing into a list if O(1)

fiery cosmos Nov 7, 2022, 12:52 AM

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then removal should be O(1) if i am removing by index?