NumPyについて

import numpy as np

# 最初に配列を作る

a = np.array([1,2,3,4,5])
print(a)
print(type(a))

# 2次元配列を作る

b = np.array([[1,2,3],[4,5,6]])
print(b)

# np.zeros()関数で、0ゼロで配列を作る　np.ones()関数だと１で配列を作る

print(np.zeros(10))
print(np.zeros((3,2)))

# np.arange()は連番で配列を作成

print(np.arange(5))
print(np.arange(2, 9))
print(np.arange(5,8,0.5))

# 行列計算

a = np.array([1, 2, 3, 4, 5])
b = a * 2
print(b)

x = np.arange(10)
y = 3 * x + 5
print(y)

# shapeプロパティで、配列の次元数を調べる

a = np.array([[1,2,3], [4,5,6]])
print(a.shape)
b = np.array([[1,2,3], [4,5,6], [7,8.9]])
print(b.shape)

# flatten()メソッドで次元数を変換する

a = np.array([[1,2,3],[4,5,6]])
print("a=", a)
b = a.flatten()
print("b=", b)

# reshape()メソッドで、配列を任意の形状に変換

a = np.array([[1,2,3],[4,5,6]])
print(a)
print(a.reshape(3,2))

# 配列要素へのアクセス

v = np.array([[[1,2,3],[4,5,6],[7,8,8]]])
a = v[0]
b = v[1:]
c = v[: , 0]
print("a=", a)
print("b=", b)
print("c=", c)