am I able to change a varable within a method in python?

Question

I am trying to make a game, but I have run into a roadblock I cannot figure out. this is the part of my code that I am failing to understand

from random import randint
apple = (0, 0)
def placeApple():
    apple = (randint(0, 19), randint(0, 19))
    fillCell(apple[0] * 20, apple[1] * 20, appleColor)
print(apple)

I feel like this should change apple to a point with a random integer 0 through 19 but when I call print(apple) in the console I always get (0, 0)

you are declaring a global variable `apple`, so when you print it, you will get the value you are clearly defining. — lmiguelvargasf, Mar 06 '19 at 02:27
https://www.datacamp.com/community/tutorials/scope-of-variables-python — Benjamin, Mar 06 '19 at 02:28
-> Call the function in the first place -> After choose between returning a value and assigning it back to apple, or add `global` before `apple in the function scope — Allan, Mar 06 '19 at 02:31

score 1 · Accepted Answer · answered Mar 06 '19 at 02:28

1

Yes, you can you can declare global apple (not recommended):

def placeApple():
    global apple
    apple = (randint(0, 19), randint(0, 19))
    fillCell(apple[0] * 20, apple[1] * 20, appleColor)

Or return it:

def placeApple():
    apple = (randint(0, 19), randint(0, 19))
    fillCell(apple[0] * 20, apple[1] * 20, appleColor)
    return apple

But for either of these you actually have to call the function, e.g. for the return option:

apple = placeApple()
print(apple)

answered Mar 06 '19 at 02:28

AChampion

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If you are going to vote down, please provide feedback. – AChampion Mar 06 '19 at 02:30
I definitely agree. I can bet somebody who marked this question as duplicated downvoted us. – lmiguelvargasf Mar 06 '19 at 02:40

lmiguelvargasf · Answer 2 · 2019-03-06T02:36:04.313

1

The problem you are facing is that you have a global variable called apple, and inside your function you have a local variable also called apple. If you want to modify a global variable inside your function you should use global:

def placeApple():
    global apple
    apple = (randint(0, 19), randint(0, 19))
    fillCell(apple[0] * 20, apple[1] * 20, appleColor)

placeApple()

print(apple)

However, changing global variables inside functions is a very bad practice since it could cause you a headache when you have to debug. With this approach, apple will be updated every time you call placeApple.

edited Mar 06 '19 at 02:36

answered Mar 06 '19 at 02:28

lmiguelvargasf

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You are still never calling the function. – Patriots299 Mar 06 '19 at 02:31
@FanJ, what do you mean? – lmiguelvargasf Mar 06 '19 at 02:32

am I able to change a varable within a method in python?

2 Answers2