python - 如何检查 DataFrame 列值是否存在于多个列表中的任何一个中，如果不存在，则填充另一列？

Question

我正在尝试使用 'boys'、'girls' 或 填充 df['Group'] 'both' 如果它们各自的 df['Color'] 值存在于任何列表中，或者在 df['Group'] 中填充 NaN 如果 df['Color'] 值不存在于任何列表中。

我有这个:

boys = ['Brown', 'Green']
girls = ['Violet', 'Verde']
both ['Black', 'White']

           Color | Group
    ---------------------
    0  | 'Brown' |   NaN
    1  | 'Green' |   NaN
    2  | 'Black' |   NaN
    3  | 'White' |   NaN
    4  | 'Verde' |   NaN
    5  | 'Purple'|   NaN
    6  | 'Violet'|   NaN

我想要这个:

           Color | Group
    ---------------------
    0  | 'Brown' |   'boys'
    1  | 'Green' |   'boys'
    2  | 'Black' |   'both'
    3  | 'White' |   'both'
    4  | 'Verde' |   'girls'
    5  | 'Purple'|   NaN
    6  | 'Violet'|   'girls'

Answer 1

您可以创建字典:

dct = dict(boys = ['Brown', 'Green'],
           girls = ['Violet', 'Verde'],
           both = ['Black', 'White'])

dct = {i: k for k, v in dct.items() for i in v}

输出:

{'Brown': 'boys',
 'Green': 'boys',
 'Violet': 'girls',
 'Verde': 'girls',
 'Black': 'both',
 'White': 'both'}

然后你可以使用方法map:

df['Group'] = df['Color'].map(dct)

输出:

    Color  Group
0   Brown   boys
1   Green   boys
2   Black   both
3   White   both
4   Verde  girls
5  Purple    NaN
6  Violet  girls