Python 将列值指定给数据帧中的唯一行

我有福勒。数据帧：

AA          AB          AC                  AD              Col_1       Col_2     Col_3    
Northeast   Argentina   Northeast Argentina South America   Corrientes  Misiones        
Northern    Argentina   Northern  Argentina South America   Chaco       Formosa   Santiago Del 

我想将其转换为：

AA          AB          AC                  AD              Col
Northeast   Argentina   Northeast Argentina South America   Corrientes
Northeast   Argentina   Northeast Argentina South America   Misiones        
Northern    Argentina   Northern  Argentina South America   Chaco
Northern    Argentina   Northern  Argentina South America   Formosa
Northern    Argentina   Northern  Argentina South America   Santiago Del 

i、 e.我希望保留前4列，但将剩余的每列值分配到单独的行中。有没有一种不使用for循环的方法可以实现这一点？

您可以尝试以下方法：

df = df.melt(id_vars=['AA','AB','AC','AD']) 
df.dropna(inplace=True)
df.drop(columns='variable', inplace=True) 
df = df.sort_values('AA').reset_index(drop=True)
df.rename(columns={'value':'Col'}, inplace=True)

          AA         AB                   AC             AD           Col
0  Northeast  Argentina  Northeast Argentina  South America    Corrientes
1  Northeast  Argentina  Northeast Argentina  South America      Misiones
2   Northern  Argentina   Northern Argentina  South America         Chaco
3   Northern  Argentina   Northern Argentina  South America       Formosa
4   Northern  Argentina   Northern Argentina  South America  Santiago Del

尝试使用：

df['Col'] = df[['Col_1', 'Col_2', 'Col_3']].values.tolist()
df = df.set_index(df.columns.drop('Col').tolist())['Col'].apply(pd.Series).stack().reset_index().rename(columns={0: 'Col'}).drop(['level_7', 'Col_1', 'Col_2', 'Col_3'], axis=1)
print(df)

输出：

          AA         AB                   AC             AD           Col
0  Northeast  Argentina  Northeast Argentina  South America    Corrientes
1  Northeast  Argentina  Northeast Argentina  South America      Misiones
2   Northern  Argentina   Northern Argentina  South America         Chaco
3   Northern  Argentina   Northern Argentina  South America       Formosa
4   Northern  Argentina   Northern Argentina  South America  Santiago Del

---

您可以通过不使用

inplace=True

来改进答案-勾选“否”，我不是dev，但更多的时候会看到这个观点并同意它。我认为这是更多的建议，检查也谢谢，这对我有帮助。我感谢你花时间帮助我成为更好的熊猫专家。