用众数填充分类列

def solve():
    import pandas as pd
    df = pd.read_csv('https://liangdaima.com/static/data/german_credit_risk.csv')
    cat_cols = df.select_dtypes(include=['object']).columns
    for col in cat_cols:
        if df[col].isnull().any():
            df[col] = df[col].fillna(df[col].mode()[0])
    print(int(df[cat_cols].isnull().sum().sum()))