Question

我有以下几种类型的多索引数据框：


import random
col3=[0,0,0,0,2,4,6,0,0,0,100,200,300,400]
col4=[0,0,0,0,4,6,8,0,0,0,200,900,400, 500]

d = {'Unit': [1, 1, 1, 1, 2, 2, 2, 3, 4, 5, 6, 6, 6, 6], 
 'Year': [2014, 2015, 2016, 2017, 2015, 2016, 2017, 2017, 2014, 2015, 2014, 2015, 2016, 2017], 'col3' : col3, 'col4' : col4 }
df = pd.DataFrame(data=d)
new_df = df.groupby(['Unit', 'Year']).sum()

           col3  col4     
Unit Year                      
1    2014     0     0      
     2015     0     0       
     2016     0     0      
     2017     0     0      
2    2015     2     4       
     2016     4     6  
     2017     6     8  
3    2017     0     0    
4    2014     0     0      
5    2015     0     0      
6    2014   100   200       
     2015   200   900  
     2016   300   400  
     2017   400   500

实际上，这当然更大，但这确实可以做到。在此数据框中，我要删除所有只有一年条目的单位。所以我想要这个：

           col3  col4     
Unit Year                      
1    2014     0     0      
     2015     0     0       
     2016     0     0      
     2017     0     0      
2    2015     2     4       
     2016     4     6  
     2017     6     8         
6    2014   100   200       
     2015   200   900  
     2016   300   400  
     2017   400   500

预先感谢您的帮助，

Jen

Answer 1

将GroupBy.transform与任何列一起使用，并将测试计数与GroupBy.size进行比较，用Series.ne进行比较，并用boolean indexing进行过滤：

df = new_df[new_df.index.get_level_values(0).duplicated(keep=False)]

或者通过Index.get_level_values获取索引值，并通过Index.duplicated进行过滤：

print (df)
           col3  col4
Unit Year            
1    2014     0     0
     2015     0     0
     2016     0     0
     2017     0     0
2    2015     2     4
     2016     4     6
     2017     6     8
6    2014   100   200
     2015   200   900
     2016   300   400
     2017   400   500

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如何删除多索引数据框中只有一个条目的行？

1 个答案: