[NumPy] numpy.ndarray

배열 생성

 

import numpy as np # 다차원 numpy 배열 생성

a = np.array([[0, 1, 2], [3, 4, 5], [6, 7, 8]])

# 배열의 shape
print(a.shape) # (3, 3)

# 배열 reshape
b = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16])
print(b.shape) # 16

b = b.reshape(4, 4)

print(b)
# [[1  2  3  4
    5  6  7  8
    9 10 11  12
    13 14 15 16]]
    
print(b.shape) # (4, 4)

 

배열 접근 (indexing)

 

import numpy as np # numpy 배열 접근

a = np.array([[0, 1, 2], [3, 4, 5], [6, 7, 8]])

print(a[0]) # [0 1 2]
print(a[0][2]) # 2
print(a[2][1]) # 7

 

배열 생성 함수

 

import numpy as np

# zeros 함수
a = np.zeros((2, 2))
print(a)
# [[0. 0.
    0. 0.]]

# empty 함수
b = np.empty((2, 2))
print(b)
# [[0. 0.
    0. 0.]]

# ones 함수
c = np.ones((2, 2))
print(c)
# [[1. 1.
    1. 1.]]

# arange 함수
d = np.arange((16))
print(d)
# [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15]

d = np.arange(2, 20, 2)
print(d)
# [2 4 6 8 10 12 14 16 18]

# linspace 함수
e = np.linspace(0, 200, 5)
print(e)
# [0. 50. 100. 150. 200.]