How to create nested lists in python?

Question

I know you can create easily nested lists in python like this:

[[1,2],[3,4]]

But how to create a 3x3x3 matrix of zeroes?

[[         


        

Answer 1

NumPy addresses this problem

http://www.scipy.org/Tentative_NumPy_Tutorial#head-d3f8e5fe9b903f3c3b2a5c0dfceb60d71602cf93

>>> a = array( [2,3,4] )
>>> a
array([2, 3, 4])
>>> type(a)

But if you want to use the Python native lists as a matrix the following helper methods can become handy:

import copy

def Create(dimensions, item):
    for dimension in dimensions:
        item = map(copy.copy, [item] * dimension)
    return item
def Get(matrix, position):
    for index in position:
        matrix = matrix[index]
    return matrix
def Set(matrix, position, value):
    for index in position[:-1]:
        matrix = matrix[index]
    matrix[position[-1]] = value