您需要在GroupBy.mean中 * 打开 * numeric_only：

gender_group = df.groupby("gender").mean(numeric_only=True)

输出：

print(gender_group)

        math_score  reading_score  writing_score  total score  average
gender                                                                
female       77.00          85.67          85.00       247.67    82.56
male         61.50          67.50          59.50       188.50    62.83