numpy.브로드캐스팅

 

a = np.ones([4,3])
a
'''
array([[1., 1., 1.],
       [1., 1., 1.],
       [1., 1., 1.],
       [1., 1., 1.]])
'''

a+[1,2,3]
'''
[2,3,4]
[2,3,4]
[2,3,4]
[2,3,4]

'''

https://docs.scipy.org/doc/numpy/user/basics.broadcasting.html

Broadcasting — NumPy v1.17 Manual

브로드캐스팅 : 아래로, 옆으로 계산을 합리적으로 확장

import numpy as np
a=np.arange(9).reshape(3,-1)
a
'''
array([[0, 1, 2],
       [3, 4, 5],
       [6, 7, 8]])
'''
b=np.arange(1000,4000,1000).reshape(3,1)
b
'''
array([[1000],
       [2000],
       [3000]])
'''
a+b
'''
array([[1000, 1001, 1002],
       [2003, 2004, 2005],
       [3006, 3007, 3008]])
'''
c=(np.arange(1,4)*0.1).reshape(3,1)
c
'''
array([[0.1],
       [0.2],
       [0.3]])
'''
a*c
array([[0. , 0.1, 0.2],
       [0.6, 0.8, 1. ],
       [1.8, 2.1, 2.4]])