Pandas Coalesce Multiple Columns，NaN

Question

我想使用熊猫coalesce 4列。我已经试过了：

final['join_key'] = final['book'].astype('str') + final['bdr'] + final['cusip'].fillna(final['isin']).fillna(final['Deal'].astype('str')).fillna(final['Id'])

当我使用它时返回：

+-------+--------+-------+------+------+------------+------------------+
| book  |  bdr   | cusip | isin | Deal |     Id     |     join_key     |
+-------+--------+-------+------+------+------------+------------------+
| 17236 | ETFROS |       |      |      | 8012398421 | 17236.0ETFROSnan |
+-------+--------+-------+------+------+------------+------------------+

Id字段未正确附加到我的join_key字段。

任何帮助，谢谢。

Answer 1

尝试一下：

import pandas as pd
import numpy as np

# setup (ignore)   
final = pd.DataFrame({
    'book': [17236],
    'bdr': ['ETFROS'],
    'cusip': [np.nan],
    'isin': [np.nan],
    'Deal': [np.nan],
    'Id': ['8012398421'],
})

# answer
final['join_key'] = final['book'].astype('str') + final['bdr'] + final['cusip'].fillna(final['isin']).fillna(final['Deal']).fillna(final['Id']).astype('str')

输出

    book    bdr     cusip   isin    Deal    Id          join_key
0   17236   ETFROS  NaN     NaN     NaN     8012398421  17236ETFROS8012398421

Answer 2

fillna的最后一个链cusip太复杂。您可以将其更改为bfill

final['join_key'] = (final['book'].astype('str') + 
                     final['bdr'] + 
                     final[['cusip', 'isin', 'Deal', 'Id']].bfill(1)['cusip'].astype(str))