Convert list to matrix (python)

Do you mean this (a matrix as a list of lists):

In [1]: matrix = [[1,2,3]]

In [2]: matrix
Out[2]: [[1, 2, 3]]

In [3]: matrix.append([4,5,6])

In [4]: matrix
Out[4]: [[1, 2, 3], [4, 5, 6]]

This can be done very easily:

def list_to_matrix(lst):
    return [lst]

Usage:

>>> lst = [1,2,3,4]
>>> lst = list_to_matrix(lst)
>>> lst
[[1,2,3,4]]

If we have cases where we might get things that are already in list-of-list form, we can add a little more robustness by doing this:

from collections import Iterable

def list_to_matrix(lst):
    if lst:
        return lst if all(isinstance(item, Iterable) and not isinstance(item, str) for item in lst) else [lst]
    else:
        # returns empty matrix if input list was empty
        return [[]]

Note that this method is pretty fragile, but at least allows you to safely pass either a base list or a list of list form blindly and get back the correct thing.

This works for any objects in list. It gives to every object its coordinates in pseudo 2d list:

def to_matrix(l, n):
    return [(x[0] / n, x[0] % n , x) for x in l]

The output for to_matrix([objects], 3) would be:

[(0, 0, some_object),
 (0, 1, some_object),
 (0, 2, some_object),
 (1, 0, some_object),
 (1, 1, some_object),
 (1, 2, some_object),
 (2, 0, some_object),
 (2, 1, some_object),
 (2, 2, some_object)]

If you need a real 2d array, this code will do the job:

def toMatrix(l, n):
    matrix = []
    for i in range (0, len(l), n):
        matrix.append(l[i:i+n])

    return matrix

def create_matrix(lst, list_of_dimensions):
    n_dimensions = len(list_of_dimensions)
    n_elements = len(lst)
    check_elements = 1
    matrix = []
    index_list = 0
    for i in list_of_dimensions:
        check_elements *= i
    if check_elements != n_elements:
        return "List elements Not Equal Product Of  Dimensions"
    for dimension in list_of_dimensions:
        sub_lst = []
        for x in range(dimension):
            sub_lst.append(lst[index_list])
            index_list += 1
        matrix.append(sub_lst)

    return matrix