将列值分配给 Pandas 数据框中的唯一行 [重复]

Question

这个问题在这里已经有了答案：

熊猫将一些列转换为行（5 个回答）

1 年前关闭。

我有一个愚蠢的。 数据框：

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 

即我想保留前 4 列，但将每个剩余的列值分配到单独的行中。 有没有办法在不使用 for 循环的情况下完成此操作？

Answer 1

你可以试试这个：

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

Answer 2

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