🔒 Smooth a wave using python, only use matplotlib.pyplot to show graph

[unreal veldt]

  #my task is to create a new_wave = [0,0,0,0,0,0]
  #and use the following formula to smoothen it
  #new_wave[i] = wave[i-1] * 0.2 + wave[i]*0.6 + wave[i+1]*0.2

  #how can i do this for 200 times such that 
  #new_wave will now be = [2.190, 4.354, 6.463, 8.492, 10.416, 12.211]

[twin path]

@unreal veldt

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[rustic relic]

just loop 200 times?

[unreal veldt]

the numbers won't add up to 2.190 if i multiply it 200 times... i've been thinking what's the smoothening logic behind this

i felt like I have to use a nested list to contain 200 iterations of the wave such that [[1,2,3,4],[x1,x2,x3,x4],y1,y2,y3,y4]] and use the previous array to generate the new array

[rustic relic]

I mean you seem to have sound logic in your pseudo python code already

wave_input = [ ... ]
for _ in range(200):
    new_wave = ...  # smoothed `wave_input`
    wave_input = new_wave
print(wave_input)

not exactly sure what the problem is
unless by "not adding up to 2.190" you mean float errors

in that case you could choose to tank performance and use fractions.Fraction if you want

[unreal veldt]

yeah this was part of my code

let me show a snippet

    new_wave = []
    for i in range(0,len(wave)):
        new_wave.insert(i,0) #insert the list with 0s so i can call its index later

    for y in range(0,times-1):
        for i in range(0,len(new_wave)):
             new_wave[i] = wave[i-1] * 0.2 + wave[i]*0.6 + wave[i+1]*0.2```

if 3 * 0.2 is already 0.6, 200 times will make it 120

[rustic relic]

notice something different between my code and yours?

[unreal veldt]

wave_input = new_wave ?

[rustic relic]

yes

[unreal veldt]

so every iteration it will rewrite the result to wave_input

[rustic relic]

then smooth that result again, and write the more smooth result to wave_input again...
repeat 200 times

[unreal veldt]

hmmmm

let me try it

[1.9782656953940232, 3.926866783344744, 5.822791923790608, 7.644162536675749, 9.370646328057173, 10.983832948161773 i got something like 1.97 which is still far off from the 2.190

need to further troubleshoot it

[rustic relic]

new_wave[i] = wave[i-1] * 0.2 + wave[i]*0.6 + wave[i+1]*0.2
might have problems when you do this on the first element i == 0 or the last element i == len(wave)-1

in fact I'm a little surprised you didn't get any errors?

[primal laurel]

Thinking about it some more I don't know how simply smoothing out the wave would cause the first element to ever not be 0, or the last one to not be 24

[unreal veldt]

yeah i will get index error, for which i used

    wave_input[i] = 0 + new_wave[i] * 0.6 + new_wave[i+1] * 0.2```

[unreal veldt]

the above formula takes weight of 0.2 from previous and the next element, and adds back remainin 0.6 of the current element

[primal laurel]

I suppose why I'm confused is that's not really smooth as much as it is leveling out, I think if you ran your code with enough iterations you might get just a straight horizontal line

[unreal veldt]

yes in that case 10,000 times will be [0.005394815860210735, 0.010782305342016428, 0.01615662151607011, 0.021511940097755214, 0.026842468439814617, 0.03214245446251207

very close to 0

but my issue now is with the 1st element not in the right value as specified in the test case

[primal laurel]

It's hard to say how to help you because what your doing seems very custom to your situation. Why are you striving to get to those values exactly? Is this part of an assignment or just a goal for some other thing you're working on?

[unreal veldt]

yeah its part of my assignment 🙂

i don't expect the answers though but i want some second eyes to give me another perspective

[twin path]

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