Numpy 常用函数笔记 线性代数相关

环境

import numpy as np
import pandas as pd
from scipy import stats

矩阵乘法 np.dot(a,b) / a.dot(b)

keypoint:

1. 想清楚应该计算 broadcasting 还是 matrix multiplication，两者容易搞混

a = np.arange(1,10,1).reshape(3,3)
b = np.eye(3)
print('a is \n',a,'\n')
print('b is \n',b)

a is 
 [[1 2 3]
 [4 5 6]
 [7 8 9]] 

b is 
 [[1. 0. 0.]
 [0. 1. 0.]
 [0. 0. 1.]]

print('a*z is \n',a