考试焦虑协方差

import pandas as pd
import numpy as np

url = 'https://liangdaima.com/static/data/ds/exam_anxiety.csv'
df = pd.read_csv(url)
r_xy = df['anxiety'].corr(df['exam_grade'])
r_xz = df['anxiety'].corr(df['revise'])
r_yz = df['exam_grade'].corr(df['revise'])
partial_r = (r_xy - r_xz * r_yz) / np.sqrt((1 - r_xz**2) * (1 - r_yz**2))
print(f'{partial_r:.4f}')