python - 我写了一个代码来计算两个 Pandas 系列之间的相关性。你能告诉我我的代码有什么问题吗？

Question

代码如下:

import numpy as np
import pandas as pd

def correlation(x, y):
    std_x = (x - x.mean())/x.std(ddof = 0)
    std_y = (y - y.mean())/y.std(ddof = 0)
    return (std_x * std_y).mean

a = pd.Series([2, 4, 5, 7, 9])
b = pd.Series([12, 10, 9, 7, 3])
ca = correlation(a, b)
print(ca)

它不返回相关值，而是返回一个 Series，键为 0 ,1, 2, 3, 4, 5，值为 -1.747504, -0.340844 , -0.043282, -0.259691, -2.531987.

请帮助我理解这背后的问题。

Answer 1

你需要调用 mean() :

return (std_x * std_y).mean()

不仅:

return (std_x * std_y).mean:

返回方法本身。完整代码:

import numpy as np
import pandas as pd

def correlation(x, y):
    std_x = (x - x.mean())/x.std(ddof = 0)
    std_y = (y - y.mean())/y.std(ddof = 0)
    return (std_x * std_y).mean()

a = pd.Series([2, 4, 5, 7, 9])
b = pd.Series([12, 10, 9, 7, 3])
ca = correlation(a, b)
print(ca)

输出:

-0.984661667628