Python matrix row shifting(Also column)-CodePudding

Is there any way that I can shift specific row in python? (It would be nice if numpy is used). I want

[[1,2],
[3,4]]

to be

[[1,2],
[4,3]].

Also for the column would be nice!

[[1,2],
[3,4]]

to be

[[1,4],
[3,2]]

Thank you.

CodePudding user response：

np.roll is your friend.

>>> import numpy as np
>>> x = np.array([[1,2],[3,4]])
>>> x
array([[1, 2],
       [3, 4]])
>>> x[1]
array([3, 4])
>>> np.roll(x[1],1)
array([4, 3])
>>> x[1] = np.roll(x[1],1)
>>> x
array([[1, 2],
       [4, 3]])
>>> x[1] = np.roll(x[1],1)
>>> x[:,1]
array([2, 4])
>>> x[:,1] = np.roll(x[:,1],1)
>>> x
array([[1, 4],
       [3, 2]])
>>>

CodePudding user response：

For the row shifting you can do:

import numpy as np

matrix = np.random.rand(5, 5)
row_no = 2
matrix[row_no, :] = np.array([matrix[row_no, -1]]   list(matrix[row_no, :-1]))

and similarly for column shifting you can simply switch the dimension orders.

import numpy as np

matrix = np.random.rand(5, 5)
col_no = 2
matrix[:, col_no] = np.array([matrix[-1, col_no]]   list(matrix[:-1, col_no]))