python - 在 Pandas DataFrame 中用逗号加入 groupby 列

Question

我有这样一个数据集:

>>> df = pd.DataFrame({'id_sin':['s123','s123','s124','s124'],
                       'raison':['first problem','second problem','album','dog']
    })
>>> df
  id_sin          raison
0   s123   first problem
1   s123  second problem
2   s124           album
3   s124             dog

这是预期的输出:

  id_sin                         raison
0   s123  first problem, second problem
1   s124                     album, dog

我尝试过的:

df['raison'] = df.groupby('id_sin')['raison'].apply(lambda x: ', '.join(x))

但不起作用...我错过了什么？感谢您的帮助!

Answer 1

尝试使用agg:

df.groupby('id_sin')['raison'].agg(', '.join).reset_index()

输出:

  id_sin                         raison
0   s123  first problem, second problem
1   s124                     album, dog