如何在pandas数据框中有条件地更改值

import pandas as pd

# 创建示例数据框
data = {'Name': ['Alice', 'Bob', 'Charlie', 'David'],
        'Age': [25, 30, 35, 40],
        'Gender': ['Female', 'Male', 'Male', 'Male']}
df = pd.DataFrame(data)

# 显示原始数据框
print("原始数据框：")
print(df)

# 设定条件和新值
condition = df['Age'] > 30
new_value = 'Unknown'

# 根据条件更改值
df.loc[condition, 'Gender'] = new_value

# 显示更改后的数据框
print("更改后的数据框：")
print(df)

原始数据框：
      Name  Age  Gender
0    Alice   25  Female
1      Bob   30    Male
2  Charlie   35    Male
3    David   40    Male
更改后的数据框：
      Name  Age   Gender
0    Alice   25  Female
1      Bob   30    Male
2  Charlie   35  Unknown
3    David   40  Unknown