How to extract the specified rows and columns of a matrix in Python numpy

This time I will bring you Python How does numpy extract the specified rows and columns of a matrix? What are the precautions for Python numpy to extract the specified rows and rows of a matrix. Here is a practical case. Let’s take a look. one time.

is as follows:

import numpy as np
a=np.arange(9).reshape(3,3)

a
Out[31]: 
array([[0, 1, 2],
  [3, 4, 5],
  [6, 7, 8]])

A certain row of the matrix

a[1]
Out[32]: array([3, 4, 5])

A certain column of the matrix

a[:,1]
Out[33]: array([1, 4, 7])

b=np.eye(3,3)
b
Out[36]: 
array([[ 1., 0., 0.],
  [ 0., 1., 0.],
  [ 0., 0., 1.]])

Assign the second column of matrix a to the first column of matrix b

b[:,0]=a[:,1]
b
Out[38]: 
array([[ 1., 0., 0.],
  [ 4., 1., 0.],
  [ 7., 0., 1.]])

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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