如何根据索引将某个值赋给pandas dataframe中的新列

import pandas as pd

# 创建一个示例 DataFrame
data = {'Name': ['John', 'Emma', 'Mike', 'Sophia'],
        'Age': [25, 28, 30, 27],
        'City': ['New York', 'London', 'Paris', 'Tokyo']}
df = pd.DataFrame(data)

# 使用索引将某个值赋给新列
df['New Column'] = 'Value'

# 打印 DataFrame
print(df)

    Name  Age      City New Column
0   John   25  New York      Value
1   Emma   28    London      Value
2   Mike   30     Paris      Value
3  Sophia   27     Tokyo      Value

import pandas as pd

# 创建一个示例 DataFrame
data = {'Name': ['John', 'Emma', 'Mike', 'Sophia'],
        'Age': [25, 28, 30, 27],
        'City': ['New York', 'London', 'Paris', 'Tokyo']}
df = pd.DataFrame(data)

# 使用 loc 方法将不同的值赋给新列
df.loc[df['Name'] == 'John', 'New Column'] = 'Value 1'
df.loc[df['Name'] == 'Emma', 'New Column'] = 'Value 2'

# 打印 DataFrame
print(df)

    Name  Age      City New Column
0   John   25  New York   Value 1
1   Emma   28    London   Value 2
2   Mike   30     Paris       NaN
3  Sophia   27     Tokyo       NaN