


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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