异常值替换为NaN再填充

def solve():
    import pandas as pd
    import numpy as np
    df = pd.read_csv('https://liangdaima.com/static/data/heart.csv')
    mean = df['chol'].mean()
    std = df['chol'].std()
    df.loc[np.abs((df['chol'] - mean) / std) > 3, 'chol'] = np.nan
    df['chol'] = df['chol'].fillna(df['chol'].median())
    print(int(df['chol'].isnull().sum()))