Two-Boolean matrix zeroer

twomatrix.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import random

def zeroify(matrix):
    height = len(matrix)
    width = len(matrix[0])

    toZero = False
    nextToZero = False

    for col in range(0, width):
        nextToZero |= matrix[0][col] == 0 # check if any cells in the first row contain zero
        for row in range(1, height):
            if matrix[row][col] == 0: # if any columns contain zero
                matrix[0][col] = 0 # put them in the first row

    for row in range(0, height):
            toZero = nextToZero # the next row is now the current row
            nextToZero = False # reset zero check for the next row
            for col in range(0, width):
                if row < (height - 1): # if we're not at the last row, check the next for zero
                    nextToZero |= matrix[row+1][col] == 0 # if the cell below the current cell contains a zero, then store that the next row does

                    if matrix[row][col] == 0: # if the current cell is zero
                        matrix[row+1][col] = 0 # set the cell below it (handles zeroing columns down)

                if toZero: # if this row contains zero
                    matrix[row][col] = 0 # zero the row
    return matrix

def main():
    mat = randomMatrix(random.randint(3,10), random.randint(3,10))
    for i in range(0, 3):
        mat[random.randint(0, len(mat) - 1)][random.randint(0, len(mat[0]) - 1)] = 0
    print "Initial matrix:"
    print prettify(mat)
    print "Zeroed matrix:"
    print prettify(zeroify(mat))


## UTILITY FUNCTIONS ##

def randomMatrix(width, height):
    matrix = []
    for i in range(0, height):
        row = []
        for j in range(0, width):
            row += [random.randint(0,255)]
        matrix += [row]
    return matrix

def prettify(matrix):
    ret = u"┌ " + (" " * len(matrix[0]) * 4) + u"┐\n"
    for row in matrix:
        rowstr = u"│ "
        for elem in row:
            elemstr = str(elem)
            rowstr += elemstr + (" " * (4 - len(elemstr)))
        rowstr += u"│\n"
        ret += rowstr
    ret += u"└ " + (" " * len(matrix[0]) * 4) + u"┘"
    return ret

if __name__ == "__main__":
    main()