List index out of range - python array error

Question

File "C:\Users\Tom\Desktop\Tetris!\tetris.py", line 206, in typeSet Globals.blockArray[i].x.append(7) IndexError: list index out of range

I get the above error for the 4th line in typeSet

At initialization:

def main():
    initialize()

def initialize():
    Globals.running = True
    addBlock()

class Globals:
    running = True
    blockArray = []
    blockNum = 0

And then later on:

def addBlock():
    Globals.blockArray.append(block())

class block:
    def __init__(self):
        self.id = Globals.blockNum
        Globals.blockNum += 1
        self.x = []
        self.y = []
        self.landed = False
        self.blockType = 1#random.randint(1,6)
        self.typeSet()


    def typeSet(self):
        i = self.id
        if self.blockType == 1:
            #square(i)
            Globals.blockArray[i].x.append(7)
            Globals.blockArray[i].y.append(0)
            Globals.blockArray[i].x.append(7)
            Globals.blockArray[i].y.append(1)
            Globals.blockArray[i].x.append(8)
            Globals.blockArray[i].y.append(0)
            Globals.blockArray[i].x.append(8)
            Globals.blockArray[i].y.append(1)

Edit: added more code and switched it so the id should start at 0. Error code hasn't changed

Seems pretty clear: whatever Globals.blockArray is, it doesn't have i members. — Daniel Roseman
– Daniel Roseman, Commented Feb 14, 2012 at 22:13
This seems to fail on it's first time through though. At initialization: blockArray = [] and then blockNum = 0 and then later on def addBlock(): Globals.blockArray.append(block()) — Tom Prats
– Tom Prats, Commented Feb 14, 2012 at 22:16
i is never 0 though. You increment it first thing to 1. blockArray[1] doesn't exist. — Daniel Roseman
– Daniel Roseman, Commented Feb 14, 2012 at 22:18
Arrgh, hang on, Globals.blockArray[i] is supposed to be the block object you're dealing with? Why on Earth don't you just refer to self then? — Daniel Roseman
– Daniel Roseman, Commented Feb 14, 2012 at 22:20
Thanks! That fixed it. The reason i didn't originally have it that way was because typeset was outside the class. But thanks a lot for catching it! — Tom Prats
– Tom Prats, Commented Feb 14, 2012 at 22:30

Bob Kaufman · Accepted Answer · 2012-02-15 16:25:59Z

1

Not enough code. The error tells you the exact problem. Globals.blockArray does not have a member at position i. That's why you shouldn't work with global variables when you can avoid them, since it can be a hard time making sure your global variables have the expected values in them.

edited Feb 15, 2012 at 16:25

Bob Kaufman

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answered Feb 14, 2012 at 22:19

S. Developer

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Comments

Dan Gerhardsson · Accepted Answer · 2012-02-14 22:18:53Z

0

I'm not sure but maybe you want to do

Globals.blockArray.append(self)

in the init function, and also increase Globals.blockNum after the assignment to self.id.

answered Feb 14, 2012 at 22:18

Dan Gerhardsson

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Jon-Eric · Accepted Answer · 2012-02-14 22:24:50Z

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Every time an instance of block is created, Globals.blockNum is incremented by 1 and self.id is set to the current value of Globals.blockNum.

Later (in typeSet) self.id is used to index into Globals.blockArray.

The error occurs when Globals.blockArray doesn't have at least self.id + 1 items in it.

If Globals.blockNum keeps increasing and its value is used (indirectly) to index into Globals.blockArray, this will likely cause the error (unless something causes Globals.blockArray to keep growing too.

answered Feb 14, 2012 at 22:24

Jon-Eric

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user229044 · Accepted Answer · 2012-02-15 19:53:55Z

0

While nothing immediate comes to mind looking at your code above, the first thing I would try would be to print the contents of Globals.blockArray, and Globals.blockArray[i].

edited Feb 15, 2012 at 19:53

user229044♦

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answered Feb 14, 2012 at 22:15

EdwardTeach

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