Python panda根据长度修改特定的列值

import pandas as pd

# 创建一个示例DataFrame
data = {'Name': ['Alice', 'Bob', 'Catherine', 'David'],
        'Age': [25, 30, 35, 40]}
df = pd.DataFrame(data)

# 定义一个函数，根据字符串长度修改值
def modify_by_length(value):
    if len(value) > 5:
        return value.upper()  # 如果长度大于5，转换为大写
    else:
        return value.lower()  # 否则转换为小写

# 应用函数到'Name'列
df['Name'] = df['Name'].apply(modify_by_length)

print(df)

       Name  Age
0     alice   25
1       bob   30
2  CATHERINE   35
3      david   40

def modify_by_length_safe(value):
    if pd.isnull(value):  # 检查是否为缺失值
        return value
    if len(value) > 5:
        return value.upper()
    else:
        return value.lower()

df['Name'] = df['Name'].apply(modify_by_length_safe)