파이썬 numpy slicing, boolean, Arithmetic operations and Broadcasting

Slicing - 잘라서 가져오기

import numpy as np
x = np.array([ 3,  6,  3,  5, 13,  9, 19])
X = np.array([[69, 10, 98, 68, 32],
               [14, 56, 73, 48, 69],
               [36, 48, 40, 28, 90],
               [45, 47, 65, 12, 95]])
               
x[1:4]
# array([6, 3, 5])

X[0:3,0:3]
# array([[69, 10, 98],
#        [14, 56, 73],
#        [36, 48, 40]])

boolean 연산

# 80보다 큰 데이터는 몇개입니까
(X > 80).sum()
# 3

# 80보다 큰 데이터를 가져오시요
X[X > 80]
#array([98, 90, 95])

Arithmetic operations and Broadcasting

2차원 배열 연산

import numpy as np
X = np.random.randint(1, 10 ,(2, 2))
Y = np.random.randint(100, 150, (2, 2))

X
# array([[7, 8],
#        [6, 3]])

Y
# array([[123, 103],
#        [131, 147]])

X + Y
# array([[112, 135],
#        [151, 130]])

X - Y
# array([[-104, -129],
#        [-147, -128]])
       
X * Y
# array([[432, 396],
#        [298, 129]])
    
X / Y
# array([[0.03703704, 0.02272727],
#        [0.01342282, 0.00775194]])