python, help

Question

import random
def matrix(rows):
mat = [[random.randint(0,10) for j in range(rows)] for i in range(rows)]
for i in range(rows):
print (mat[i])
def tr_mat (mat):
rows = len(mat)
cols = len(mat[0])
tr_mat = matrix(cols, rows)
for i in range(rows):
for j in range(cols):
tr_mat[j][i] = mat[i][j]
return tr_mat
mat=matrix(3)
print(tr_mat(mat))
help me to change the code, error is the (object of type 'NoneType' has no len()) and it about rows and cols in (def tr_mat)

Answer 1

Here are a few points to notice:

● Your matrix function is not returning anything, therefore:

mat=matrix(3)

Sets the <mat> to None, there was nothing returned by matrix function. The error you get was triggered when you try "rows = len(mat)", but <mat> is None. Add "return mat" after the for loop to show the matrix.

● In the tr_mat function you try to call the matrix function passing two arguments, <cols> & <rows>;

tr_mat = matrix(cols, rows)

But the matrix function signature shows the matrix function only accepts one parameter, either change the matrix function signature, or how it is called in tr_matrix function.

Hth, cmiiw