CODEWITHSUNDEEP
pythonclassmultidimensional-arraypickleindexoutofrangeexception
Corey Iles
Corey Iles

Reputation: 155

"List index out of range" on 3D array of objects

I'm just simply trying to store a bunch of blocks in a bunch of chunks. It's for a very simple voxel world. There are three class levels at the moment in the test code (I was going to play around with the pickle module and serializing): the world, chunks in the world, and blocks in the chunks.

This is the trace:

Traceback (most recent call last):  File "C:/Crayder/Scripts/pickle 
test/pickle1.py", line 27, in <module>    aWorld = world();  File 
"C:/Crayder/Scripts/pickle test/pickle1.py", line 25, in __init__    
self.chunks[cX][cY] = chunk(cX, cY);  File "C:/Crayder/Scripts/pickle 
test/pickle1.py", line 18, in __init__    self.blocks[bX][bY][bZ] = 
block((self.x * 16) + bX, (self.y * 16) + bY, bZ); IndexError: list 
index out of range

And here is the code:

class block:
    def __init__(self, x, y, z, data = 0):
        self.x = x;
        self.y = y;
        self.z = z;
        self.data = data;

class chunk:
    def __init__(self, x, y):
        self.x = x;
        self.y = y;
        self.blocks = [];
        for bX in range(16):
            for bY in range(16):
                for bZ in range(64):
                    self.blocks[bX][bY][bZ] = block((self.x * 16) + bX, (self.y * 16) + bY, bZ);

class world:
    def __init__(self):
        self.chunks = [];
        for cX in range(16):
            for cY in range(16):
                self.chunks[cX][cY] = chunk(cX, cY);

aWorld = world();

print(aWorld.chunks[2][2].blocks[2][2][2]);

What am I doing wrong here?

Upvotes: 0

Views: 659

Answers (1)

Ajit George
Ajit George

Reputation: 3319

You are creating empty lists and then trying to assign into them. The error you're getting is the same as

l = [] 
l[0] = 'something'  # raises IndexError because len(l) == 0

You have to either append elements to the list:

l = []
l.append('something')

or prepopulate the lists so that you can then replace the elements:

l = list(range(5))
l[4] = 'last element'

For your two dimensional case:

self.chunks = list(range(16))
for cX in range(16):
    self.chunks[cX] = list(range(16))
    for cY in range(16):
        self.chunks[cX][cY] = chunk(cX, cY)

which you can extrapolate to the three dimensional case.

Upvotes: 1

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