Matrices in Python

To solve compute problems we use different type of data structures like array , maps, etc. One such data structure is matrices or 2D arrays. Matrices act as foundation for other data structure like graphs .

Define matrices in python

matrix = [  [1, 2, 3],  [4, 5, 6],  [7, 8, 9] ]

matrix = [  [1, 2, 3],  [4, 5, 6],  [7, 8, 9] ]

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Define a 3x3 matrix in python, row(R) equals 3 and column(C) equals 3

matrix_3x3 = [[0]* 3 for in range(3)]*

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There are popular problems in matrices:

Transpose a matrix:

def calculate_transpose_of_matrix(mat: list[list]) -> list[list]:  N = len(mat)  for i in range(N):  for j in range(i+1, N):  mat[i][j], mat[j][i] = mat[j][i], mat[i][j]

def calculate_transpose_of_matrix(mat: list[list]) -> list[list]:  N = len(mat)  for i in range(N):  for j in range(i+1, N):  mat[i][j], mat[j][i] = mat[j][i], mat[i][j]

return mat`

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Print matrix in spiral pattern:

def print_matrix_in_spiral(mat: list[list]) -> list[list]:  R = len(mat)  C = len(mat[0])

def print_matrix_in_spiral(mat: list[list]) -> list[list]:  R = len(mat)  C = len(mat[0])

top = 0 left = 0 bottom = R - 1 right = C - 1

while top <= bottom and left <= right: for i in range(left, (right + 1)): print(mat[top][i], end=" ") top += 1 for i in range(top, (bottom + 1)): print(mat[i][right], end=" ") right -= 1 if top <= bottom: for i in range(right, (left - 1), -1): print(mat[bottom][i], end=" ") bottom -= 1 if left <= right: for i in range(bottom, (top - 1), -1): print(mat[i][left], end= " ") left += 1`

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