Python+Numpy------数组运算

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1、数组运算

(1)数组加法：array([20,31,42,53])=array([20,30,40,50])+array([0,1,2,3])

 from numpy import *a=array([20,30,40,50])b=arange(4)a+b

(2)数组减法：array([20,29,38,47])=array([20,30,40,50])-array([0,1,2,3])

 from numpy import *a=array([20,30,40,50])b=arange(4)c=a-b

(3)数组乘法：array([2,0],[0,4])=array([1,1],[0,1])*array([2,0],[3,4])

数组点积

矩阵乘积

  from numpy import *

 a=array([1,1],[0,1]) b=array([2,0],[3,4]) a*b#点积

dot表示乘积；一维数组计算的是点积；二维数组计算的是矩阵乘积。

  from numpy import * a=array([1,1],[0,1]) b=array([2,0],[3,4]) dot(a,b)#矩阵乘积

(4)数组乘方：array([0,1,2,3])的二次方=array([0,1,4,9])

 from numpy import *b=arange(4)b**2

（5）数组除法：array([20.,15.,10.,5.])=array([20,30,40,50])/array([1,2,4,10])

 from numpy import *a=array([20,30,40,50])b=array([1,2,4,10])a/b

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