Zero Matrix: Write an algorithm such that if an element in an MxN matrix is 0, its entire row and column are set to 0.

zero_matrix.py

class Matrix:

    @staticmethod
    def zero(M, m, n):
        """Zeroes out the whole row and column if one elements is found to be zero.

        Args:
            M (array) of m rows and n columns
            m (int) of rows
            n (int) of columns

        Returns:
            M (array) modified with zeroed out rows/columns if applicable
        """
        row = [0] * m
        col = [0] * n

        for i in range(m):
            if 0 in M[i]:
                row[i] = 1
            for j in range(n):
                if M[i][j] is 0:
                    col[j] = 1
        for x in range(m):
            if row[x] == 1:
                M[x] = [0] * n

        for y in range(n):
            if col[y] == 1:
                for z in range(m):
                    M[z][y] = 0
        return M

import unittest
class TestZeroMatrix(unittest.TestCase):

    def test_empty(self):
        M = []
        self.assertEqual(M, Matrix.zero(M, 0, 0))

    def test_no_zeroes(self):
        M = [
        [1, 2],
        [2, 1]
        ]
        self.assertEqual(M, Matrix.zero(M, 2, 2))

    def test_one_zero(self):
        M = [
        [0, 2],
        [2, 1]
        ]
        R = [
        [0, 0],
        [0, 1]
        ]
        self.assertEqual(R, Matrix.zero(M, 2, 2))

    def test_two_zeroes(self):
        M = [
        [0, 2],
        [2, 0]
        ]
        R = [
        [0, 0],
        [0, 0]
        ]
        self.assertEqual(R, Matrix.zero(M, 2, 2))

    def test_no_zero_m_by_n(self):
        M = [
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7]
        ]
        R = [
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7]
        ]
        self.assertEqual(R, Matrix.zero(M, 5, 6))

    def test_one_zero_m_by_n(self):
        M = [
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 0, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 4, 5, 6, 7]
        ]
        R = [
        [2, 2, 0, 5, 6, 7],
        [2, 2, 0, 5, 6, 7],
        [0, 0, 0, 0, 0, 0],
        [2, 2, 0, 5, 6, 7],
        [2, 2, 0, 5, 6, 7]
        ]
        self.assertEqual(R, Matrix.zero(M, 5, 6))

    def test_multiple_0h_m_by_n(self):
        M = [
        [2, 2, 4, 5, 0, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 2, 0, 5, 6, 7],
        [2, 2, 4, 5, 6, 7],
        [2, 0, 4, 5, 6, 7]
        ]
        R = [
        [0, 0, 0, 0, 0, 0],
        [2, 0, 0, 5, 0, 7],
        [0, 0, 0, 0, 0, 0],
        [2, 0, 0, 5, 0, 7],
        [0, 0, 0, 0, 0, 0]
        ]
        self.assertEqual(R, Matrix.zero(M, 5, 6))

if __name__ == '__main__':
     unittest.main()