matrix_rotation.py

import itertools

given_matrix = [[1, 2, 3, 4, 5, 6],
                [7, 8, 9, 10, 11, 12],
                [13, 14, 15, 16, 17, 18],
                [19, 20, 21, 22, 23, 24],
                [25, 26, 27, 28, 29, 30],
                [31, 32, 33, 34, 35, 36]]

rotations = 2


# Rotate a matrix counterclockwise r times
def matrixRotation(matrix, r):
    # Number of rows in the matrix
    rows = len(matrix)
    # Number of columns in the matrix
    columns = len(matrix[0])

    # New list that will contain each slice of the matrix in a new list
    matrices = []
    # The number of slices in the matrix
    matrix_num = int(min(rows, columns) / 2)
    i = 0
    while i < matrix_num:
        single_matrix = []
        # The top (left to right) of the matrix slice
        top = matrix[i][i:columns-i]
        # The right side (top to bottom) of the matrix slice
        right = [matrix[row][columns-1-i] for row in range(i+1, rows-i-1)]
        # The bottom (right to left) of the matrix slice
        bottom = matrix[rows-i-1][i:columns-i]
        bottom.reverse()
        # The left side (bottom to top) of the matrix slice
        left = [matrix[row][i] for row in range(i+1, rows-i-1)]
        left.reverse()

        i += 1

        # Append each side of the matrix slice to the single_matrix list, with each side in its own list
        single_matrix.extend([top, right, bottom, left])
        # Turn the single_matrix list of lists into a single list
        single_matrix = [x for x in single_matrix if x != []]
        # Turn into a flat list
        single_matrix = list(itertools.chain(*single_matrix))
        # Rotate this flat list counter clockwise by r
        # If r is more than the length of the matrix it's more efficient to use r % len
        new_r = r % len(single_matrix)
        for _ in range(new_r):
            single_matrix.append(single_matrix.pop(0))
        # Append the rotated list to the matrices list
        matrices.append(single_matrix)

    flat_matrices = list(itertools.chain(*matrices))
    new_matrix = [[] for i in range(rows)]
    i = 0
    rs = rows
    cs = columns
    # Create new matrix from rotated matrix
    while i <= matrix_num:
        # Create new top
        new_matrix[i][i:i] = flat_matrices[:cs]
        del flat_matrices[:cs]
        # Create new right side
        for k in range(rs - 2):
            new_matrix[k + 1 + i].insert(i, flat_matrices[k])
        del flat_matrices[:rs - 2]
        # Create new bottom
        new_matrix[rows - 1 - i][i:i] = flat_matrices[:cs][::-1]
        del flat_matrices[:cs]
        # Create new left side
        for k in range(rs - 2):
            new_matrix[rs - 2 - k + i].insert(i, flat_matrices[k])
        del flat_matrices[:rs - 2]
        i += 1
        rs -= 2
        cs -= 2

    # Print each row as a string joined by a space
    for row in new_matrix:
        print(' '.join(str(x) for x in row))


matrixRotation(given_matrix, rotations)