Rotate Matrix

rotate_matrix_1_7.py

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

# Rotate Matrix
# Given an image represented by an NxN matrix, where each pixel in the image is 4 bytes,
# write a method to rotate the image by 90 degrees. Can you do this in place?

import copy

class RotateMatrix:
  def __init__(self, org_matrix):
    self.org_matrix = org_matrix
    self.size = len(self.org_matrix)

  def rotate(self):
    result = copy.deepcopy(self.org_matrix)

    for i, row in enumerate(self.org_matrix):
      for j, ele in enumerate(row):
        x = i + (-i+j)
        y = j + ((self.size-1)-i-j)
        result[x][y] = ele

    return result

  def print_matrix(self, matrix):
    return "\n".join([str(m) for m in matrix])

if __name__ == '__main__':
  matrix = \
      [
        [1, 2, 3],
        [4, 5, 6],
        [7, 8, 9]
      ]
  matrix_2 = \
      [
        [ 1, 2, 3, 4],
        [ 5, 6, 7, 8],
        [ 9,10,11,12],
        [13,14,15,16],
      ]
  matrix_3 = \
      [
        [ 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],
      ]
  rotate_matrix = RotateMatrix(matrix)
  rotated_matrix = rotate_matrix.rotate()

  print "INPUT"
  print rotate_matrix.print_matrix(matrix)
  print "OUTPUT"
  print rotate_matrix.print_matrix(rotated_matrix)

The other solutions

• https://www.youtube.com/watch?v=aClxtDcdpsQ