将两个 Pandas 具有相同列的数据框组合成一个字符串列

Question

我有两个 Pandas 数据帧，即：

+-------+-------------------+--+
| Name  |       Class       |  |
+-------+-------------------+--+
| Alice | Physics           |  |
| Bob   | "" (Empty string) |  |
+-------+-------------------+--+

Table 2:

+-------+-----------+
| Name  |   Class   |
+-------+-----------+
| Alice | Chemistry |
| Bob   | Math      |
+-------+-----------+

有没有办法在 Class 列上轻松组合它，所以结果 table 就像：

+-------+--------------------+
| Name  |       Class        |
+-------+--------------------+
| Alice | Physics, Chemistry |
| Bob   | Math               |
+-------+--------------------+

我还想确保在添加列时没有多余的逗号。谢谢！

Answer 1

试试 concat 和 groupby:

>>> pd.concat([df1, df2]).groupby("Name").agg(lambda x: ", ".join(i for i in x.tolist() if len(i.strip())>0)).reset_index()
                    
Name                Class     
Alice  Physics, Chemistry
Bob                  Math

Answer 2

df = pd.DataFrame({'Name':['Alice','Bob'],
                   'Class':['Physics',np.nan]})
df2 = pd.DataFrame({'Name':['Alice','Bob'],
                   'Class':['Chemistry','Math']})

df3 = df.append(df2).dropna(subset=['Class']).groupby('Name')['Class'].apply(list).reset_index()

# to remove list
df3['Class'] = df3['Class'].apply(lambda x: ', '.join(x))

将两个 Pandas 具有相同列的数据框组合成一个字符串列

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