numpy 入门级教程

import numpy as np
a = np.array([1,2,3,4,5])
b = np.zeros((2,3))
c = np.ones([2,2])
d = np.arange(3,7)
print(a,'n',b,'n','n',c,'n',d,'n')

a1 = np.linspace(0,1,5)
b1 = np.random.rand(2,8)
print(a1,'n',b1)

print(type(a1))

a2 = np.zeros((3,2), dtype = np.int32)
print(type(a2))
b2 = b.astype(int)
print(type(b2))

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

# 向量点乘运算
print(np.dot(a,b))

# 矩阵乘法运算
print(a @ b)

c = np.sqrt(a)
print(c)
print(a * 2)

# 不同尺寸的数组仍可进行计算
a1 = np.array([ [1],
                [2],
                [3]])
b1 = np.array([4,5,6])
print(a1 + b1)

# 返回最大值，最小值
print(max(a))
print(min(a))
# 返回最大值最小值的索引
print(np.argmax(a))
print(np.argmin(a))

# 获取行，列
s = np.array([
    [1,2,3],
    [4,5,6]
])
s1 = np.sum(s, axis=1)
s2 = np.sum(s, axis=0)
print(s1,'n',s2)

a = np.array([
    [1,2,3],
    [4,5,6],
    [7,8,9]
])
print(a[1][:2])
print(a[1][1])