如何合并重叠的列 [英] How to merge overlapping columns

问题描述

我有两个这样的数据集

import pandas as pd
import numpy as np
df1 = pd.DataFrame({'id': [1, 2,3,4,5], 'first': [np.nan,np.nan,1,0,np.nan], 'second': [1,np.nan,np.nan,np.nan,0]})
df2 = pd.DataFrame({'id': [1, 2,3,4,5, 6], 'first': [np.nan,1,np.nan,np.nan,0, 1], 'third': [1,0,np.nan,1,1, 0]})

我想得到

result = pd.merge(df1, df2,  left_index=True, right_index=True,on='id', how= 'outer')
result['first']= result[["first_x", "first_y"]].sum(axis=1)
result.loc[(result['first_x'].isnull()) & (result['first_y'].isnull()), 'first'] = np.nan
result.drop(['first_x','first_y'] , 1)

  id    second  third   first
0   1   1.0      1.0    NaN
1   2   NaN      0.0    1.0
2   3   NaN      NaN    1.0
3   4   NaN      1.0    0.0
4   5   0.0      1.0    0.0
5   6   NaN      0.0    1.0

问题在于实际数据集包含大约200个变量，而我的方法很长.如何使其更容易?谢谢

The problem is that the real dataset includes about 200 variables and my way is very long. How to make it easier? Thanks

推荐答案

您应该可以使用

You should be able to use combine_first:

>>> df1.set_index('id').combine_first(df2.set_index('id'))
    first  second  third
id                      
1     NaN       1      1
2       1     NaN      0
3       1     NaN    NaN
4       0     NaN      1
5       0       0      1
6       1     NaN      0

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