🔒 Help trying to convert star data into Cartesian coordinates

[pulsar beacon]

hi, im fairly new to python and coding in general. im running into a error "Index Error: list out of range" whenever i try to run the code. im using data from a csv file and i need to get the data from columns 7 & 8. any advice

[fleet elbow]

@pulsar beacon

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[graceful meadow]

can you share the csv file?

!paste

[fleet elbow]

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[stone arrow]

remember indices start at 0
so columns 7 & 8 would actually be columns[6] and columns[7] in code

but also, iterating through each row is a bad idea if you want it to run fast

[pulsar beacon]

yes i can, is this good?

[graceful meadow]

yes, but I'd recommend using a proper csv module for parsing the text

cells like this will cause issues if you naively use .split()

[stone arrow]

the second image looks like they're already using pandas or something though
and if this is the case, you shouldn't need to parse line by line yourself at all, a pd.read_csv('path/to/csv') should allow you to load the data into a df directly from the file

[pulsar beacon]

i am using pandas

[graceful meadow]

this code doesn't look like it though

[stone arrow]

why not pd.read_csv then?

[pulsar beacon]

did i use pd.read_csv right here?

[stone arrow]

yeah just like that, though you can remove the df = pd.DataFrame(stars, ...) line, pd.read_csv already returns a DataFrame, so stars is already what you need
and you could just use this dataframe instead of parsing line by line again

[pulsar beacon]

im sorry, im new to this. is this what you mean? im struggling with figuring out how to loop through the data and only get date from the specifc columns 7 & 8 to insert into my equation

[white parrot]

import csv
import math

with open("example.csv","r") as csvfile:
    reader=csv.reader(csvfile,delimiter=",")
    i=0
    for row in reader:
        if i>0:
            x=math.cos(float(row[8]))*math.cos(float(row[7]))
            y=math.sin(float(row[8]))*math.sin(float(row[7]))
            print(x,y)
        i+=1 

@pulsar beacon The above codes solve your problem.

@pulsar beacon Remember that line 0 contains the headers, not the numeric values!

[pulsar beacon]

im still getting a error, what am i doing wrong?

[white parrot]

@pulsar beacon You made an indentation error. The x, y and print statements are written four spaces after the if block.

@pulsar beacon Make the alignments as you see on the screen

[pulsar beacon]

thanks a lot

[pulsar beacon]

is there a way i can get it to loop through every row of data?

[white parrot]

@pulsar beacon Don't forget to vote if the problem is solved.

yes

[pulsar beacon]

how would i do that?

[white parrot]

import csv

with open("example.csv","r") as csvfile:
    reader=csv.reader(csvfile,delimiter=",")
    i=0
    for row in reader:
        if i>0:
            for number in range(0,len(row)):
                print(number,end=",")
            print("")
            print("="*80)
        i+=1

[pulsar beacon]

thank you

[fleet elbow]

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🔒 Help trying to convert star data into Cartesian coordinates