python - 如何转换数据框以便列值是行值

Question

我有以下数据框，如下所示:

df = pd.DataFrame({'fruit': ['berries','berries', 'berries', 'tropical', 
'tropical','tropical','berries','nuts'], 
           'code': [100,100,100,200,200, 300,400,500],
           'subcode': ['100A', '100B', '100C','200A', '200B','300A', 
           '400A', '500A']})


    code    fruit   subcode
  0 100     berries 100A
  1 100     berries 100B
  2 100     berries 100C
  3 200     tropica 200A
  4 200     tropical 200B
  5 300     tropical 300A
  6 400     berries 400A
  7 500     nuts    500A

我想将数据框转换为这种格式:

    code    fruit   subcode1 subcode1 subcode1
  0 100     berries 100A      100B   100C
  3 200     tropica 200A      200B
  5 300     tropical 300A
  6 400     berries 400A
  7 500     nuts    500A 

不幸的是，我不知道如何继续。我咨询过像Unmelt Pandas DataFrame这样的帖子, 并具有堆栈和取消堆栈的组合。我怀疑也涉及一些串联。如果有任何建议可以帮助我指明正确的方向，我将不胜感激!

Answer 1

您可以使用groupby，获取值并将它们转换为系列。

df.groupby(['code','fruit'])['subcode'].apply(
         lambda x: x.values
      ).apply(pd.Series)
       .add_prefix('subcode_')

                subcode_0 subcode_1 subcode_2
code fruit                                 
100  berries       100A      100B      100C
200  tropical      200A      200B       NaN
300  tropical      300A       NaN       NaN
400  berries       400A       NaN       NaN
500  nuts          500A       NaN       NaN