CODEWITHSUNDEEP
python
Rakshith G B
Rakshith G B

Reputation: 826

Dictionary values don't remain constant

The final values are different from than during individual key fills, when key "0" is getting filled with

{0: (0, 0), 1: (1, 0), 2: (2, 0), 3: (3, 0), 4: (4, 0),
 5: (5, 0), 6: (6, 0), 7: (7, 0), 8: (8, 0), 9: (9, 0),
 10: (10, 0), 11: (11, 0), 12: (12, 0)

etc; these values are changed once the outer while loop is fully completed. They turn into:

{0: (0, 0), 1: (0, 0), 2: (-1, 0), 3: (-2, 0), 4: (-3, 0), 
 5: (-4, 0), 6: (-5, 0), 7: (-6, 0), 8: (-7, 0), 9: (-8, 0), 
 10: (-9, 0), 11: (-10, 0), 12: (-11, 0)

I'm not able to figure out why. Any help is much appreciated. You can uncomment the print statement for reference.

The code:

import numpy as np
from math import cos,sin,pi

ANGLE_ACCURACY = 0.5

noOfAnglesLimit = (360.0/ANGLE_ACCURACY)*0.5
angle = 0

polarLut = dict()
inner = dict()

while angle<noOfAnglesLimit:
    theta = (pi/180.0)*(angle*ANGLE_ACCURACY)

    radius = 0
    while radius<=200:
        x = int(float(radius)*cos(theta)+0.5)
        y = int(float(radius)*sin(theta)+0.5)
        inner[radius] = (x,y)
        radius+=1        

    polarLut[angle] = inner
    #print(polarLut)
    angle+=1

import json

with open('file.txt', 'w') as file:
     file.write(json.dumps(polarLut))

Upvotes: 0

Views: 50

Answers (2)

AKX
AKX

Reputation: 169407

You only have one inner dictionary, which you assign to all values of the polarLut dictionary, then go on modifying it again for the next angle.

You'll want something like

polarLut = dict()

while angle < noOfAnglesLimit:
    theta = (pi / 180.0) * (
        angle * ANGLE_ACCURACY
    )
    inner = dict()
    radius = 0
    while radius <= 200:
        x = int(float(radius) * cos(theta) + 0.5)
        y = int(float(radius) * sin(theta) + 0.5)
        inner[radius] = (x, y)
        radius += 1

    polarLut[angle] = inner
    angle += 1

instead.

Also, I would suggest using for angle in range(noOfAnglesLimit) instead, it's more Pythonic.

Upvotes: 3

Matthieu Brucher
Matthieu Brucher

Reputation: 22043

You are always storing the same dictionary inside polarLut, so all the entries point to the same original inner.

Move the declaration of inner inside your while loop.

Upvotes: 1

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