如何在Panda Data框架中组合两列时删除nan值？

我正在尝试但是在组合DataFrame的两列时无法移除nan.

数据如下：

Feedback_id                  _id
568a8c25cac4991645c287ac     nan    
568df45b177e30c6487d3603     nan    
nan                          568df434832b090048f34974       
nan                          568cd22e9e82dfc166d7dff1   
568df3f0832b090048f34711     nan
nan                          568e5a38b4a797c664143dda   

我想要：

Feedback_request_id
568a8c25cac4991645c287ac
568df45b177e30c6487d3603
568df434832b090048f34974
568cd22e9e82dfc166d7dff1
568df3f0832b090048f34711
568e5a38b4a797c664143dda

这是我的代码：

df3['Feedback_request_id'] = ('' if df3['_id'].empty else df3['_id'].map(str)) + ('' if df3['Feedback_id'].empty else df3['Feedback_id'].map(str))

输出我得到：

Feedback_request_id
568a8c25cac4991645c287acnan
568df45b177e30c6487d3603nan
nan568df434832b090048f34974
nan568cd22e9e82dfc166d7dff1
568df3f0832b090048f34711nan
nan568e5a38b4a797c664143dda

我试过这个,也是：

df3['Feedback_request_id'] = ('' if df3['_id']=='nan' else df3['_id'].map(str)) + ('' if df3['Feedback_id']=='nan' else df3['Feedback_id'].map(str))

但它给出了错误：

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

解决方法:

您可以使用combine_first或fillna：

print df['Feedback_id'].combine_first(df['_id'])
0    568a8c25cac4991645c287ac
1    568df45b177e30c6487d3603
2    568df434832b090048f34974
3    568cd22e9e82dfc166d7dff1
4    568df3f0832b090048f34711
5    568e5a38b4a797c664143dda
Name: Feedback_id, dtype: object

print df['Feedback_id'].fillna(df['_id'])
0    568a8c25cac4991645c287ac
1    568df45b177e30c6487d3603
2    568df434832b090048f34974
3    568cd22e9e82dfc166d7dff1
4    568df3f0832b090048f34711
5    568e5a38b4a797c664143dda
Name: Feedback_id, dtype: object