Multidimensional array in Python

Question

I have a little Java problem I want to translate to Python. Therefor I need a multidimensional array. In Java it looks like:

double dArray[][][] = new double[x.l         


        

Answer 1

To create a standard python array of arrays of arbitrary size:

a = [[0]*cols for _ in [0]*rows]

It is accessed like this:

a[0][1] = 5 # set cell at row 0, col 1 to 5

A small python gotcha that's worth mentioning: It is tempting to just type

a = [[0]*cols]*rows

but that'll copy the same column array to each row, resulting in unwanted behaviour. Namely:

>>> a[0][0] = 5
>>> print a[1][0]
5