np.dot()计算两个变量的乘积

np.dot()计算两个变量的乘积，返回的是一个值

import numpy as np
np.dot(a, b, out=None)  #该函数的作用是获取两个元素a,b的乘积.

a,b可以是数组或者int

print(np.dot(1,10)) #10

还可以

import numpy as np

np.random.seed(20200623)
x, y = np.random.randint(0, 20, size=(2, 4))

print(x)  # [10  2  1  1]
print(y)  # [16 18 11 10]

z = np.corrcoef(x, y)
print(z)
# [[1.         0.48510096]
#  [0.48510096 1.        ]]

a = np.dot(x - np.mean(x), y - np.mean(y))
b = np.sqrt(np.dot(x - np.mean(x), x - np.mean(x)))
c = np.sqrt(np.dot(y - np.mean(y), y - np.mean(y)))
print(a / (b * c))  # 0.4851009629263671