In python, appending to a list stored in a dictionary key using += []

Here’s what I tried… I get a syntax error on the line "context[‘x’] += [ … ]"… basically I want to pass my variables into the function as a dictionary reference… modify a few hash tags and hopefully have a persistent state between function calls.

import numpy as np

def draw_init():
    context={'x': [], 'y' : [], 'n' : [], 'count' : 0}
    return context

def draw_circle(context, radius):
    N0 = 16
    
    for i in range(0, N0-1):
        t                  = float(i) * 2.0 / float(N0) * np.pi;
        context['x']      += [float(radius) * np.sin(t)]
        context['y']      += [float(radius) * np.cos(t)]
        context['n']      += [context['count']]
        context['count']  += 1
                
context = draw_init

draw_circle(context, 500)
draw_circle(context, 200)
draw_circle(context, 100)

>Solution :

import numpy as np

def draw_init():
    context={'x': [], 'y' : [], 'n' : [], 'count' : 0}
    return context

def draw_circle(context, radius):
    N0 = 16

    for i in range(0, N0-1):
        t                  = float(i) * 2.0 / float(N0) * np.pi;
        context['x']      += [float(radius) * np.sin(t)]
        context['y']      += [float(radius) * np.cos(t)]
        context['n']      += [context['count']]
        context['count']  += 1

context = draw_init()

draw_circle(context, 500)
draw_circle(context, 200)
draw_circle(context, 100)

Note the

context['n']      += [context['count']]

and the

context = draw_init()