Transpose a matrix in Python

Question

I m trying to create a matrix transpose function in Python  A matrix is a two dimensional array  represented as a list of lists of integers  For example  the following is a 2X3 matrix  meaning the height of the matrix is 2 and the width is 3   A   1  2  3       4  5  6    To be transposed the jth item in the ith index should become the ith item in the jth index  Here s how the above sample would look transposed   gt  gt  gt  transpose   1  2  3                   4  5  6      1  4    2  5    3  6    gt  gt  gt  transpose   1  2                   3  4      1  3    2  4    How can I do this

User · Answer

Is there a prize for being lazy and using the transpose function of NumPy arrays      import numpy as np  a   np array   1 2 3    4 5 6     b   a transpose

User · Answer

You can use zip with   to get transpose of a matrix    gt  gt  gt  A      1  2  3    4  5  6    gt  gt  gt  zip  A    1  4    2  5    3  6    gt  gt  gt  lis      1 2 3         4 5 6        7 8 9    gt  gt  gt  zip  lis    1  4  7    2  5  8    3  6  9     If you want the returned list to be a list of lists    gt  gt  gt   list x  for x in zip  lis     1  4  7    2  5  8    3  6  9    or  gt  gt  gt  map list  zip  lis     1  4  7    2  5  8    3  6  9

User · Answer

If we wanted to return the same matrix we would write   return    m row  col  for col in range 0 width    for row in range 0 height      What this does is it iterates over a matrix m by going through each row and returning each element in each column  So the order would be like     1 2 3    4 5 6    7 8 9     Now for question 3  we instead want to go column by column  returning each element in each row  So the order would be like     1 4 7    2 5 8    3 6 9     Therefore just switch the order in which we iterate   return    m row  col  for row in range 0 height    for col in range 0 width

[python] Transpose a matrix in Python

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