I have a text file which contains matrix of N * M dimensions.
For example the input.txt file contains the following:
Consider
with open('input.txt', 'r') as f:
l = [[int(num) for num in line.split(',')] for line in f]
print(l)
produces
[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 2, 1, 0, 2, 0, 0, 0, 0], [0, 0, 2, 1, 1, 2, 2, 0, 0, 1], [0, 0, 1, 2, 2, 1, 1, 0, 0, 2], [1, 0, 1, 1, 1, 2, 1, 0, 2, 1]]
Note that you have to split on commas.
If you do have blank lines then change
l = [[int(num) for num in line.split(',')] for line in f ]
to
l = [[int(num) for num in line.split(',')] for line in f if line.strip() != "" ]