matrix.py

import pprint

m = [(0, 0, 0, 0, 0),
     (0, 0, 0, 0, 0),
     (0, 0, 0, 0, 0),
     (-1, 0, 0, 0, 0),
     (-1, -1, 0, 0, 0),]

_x = len(m[0])
_y = len(m)

out = []
for x in range(1, _x+1):
    out.append([(_x-x, y) for y in range(_y)])
    
pprint.pprint(out)

#[[(4, 0), (4, 1), (4, 2), (4, 3), (4, 4)],
# [(3, 0), (3, 1), (3, 2), (3, 3), (3, 4)],
# [(2, 0), (2, 1), (2, 2), (2, 3), (2, 4)],
# [(1, 0), (1, 1), (1, 2), (1, 3), (1, 4)],
# [(0, 0), (0, 1), (0, 2), (0, 3), (0, 4)]]