Read flat list into multidimensional array/matrix in python

Question

I have a list of numbers that represent the flattened output of a matrix or array produced by another program, I know the dimensions of the original array and want to read t

Answer 1

If you dont want to use numpy, there is a simple oneliner for the 2d case:

group = lambda flat, size: [flat[i:i+size] for i in range(0,len(flat), size)]

And can be generalized for multidimensions by adding recursion:

import operator
def shape(flat, dims):
    subdims = dims[1:]
    subsize = reduce(operator.mul, subdims, 1)
    if dims[0]*subsize!=len(flat):
        raise ValueError("Size does not match or invalid")
    if not subdims:
        return flat
    return [shape(flat[i:i+subsize], subdims) for i in range(0,len(flat), subsize)]