在pandas中選擇值為1的列名

Question

我有这个数据帧：

    Course_2013     AP  Advanced    Vocational  Basic   ESL 
0   7th Math Enrich  0    1             0         0      0   
1   8th Math Enrich  0    1             0         0      0   
2   8th Science Enr  0    1             0         0      0   
3   Accounting I     0    0             0         1      0               
4   Accounting II    0    0             0         0      1   

我需要创建名为“category”的新列，该列包含每行中包含1的列的列名：

    Course_2013     AP  Advanced    Vocational  Basic   ESL category
0   7th Math Enrich  0    1             0         0      0   Advanced
1   8th Math Enrich  0    1             0         0      0   Advanced
2   8th Science Enr  0    1             0         0      0   Advanced
3   Accounting I     0    0             0         1      0   Basic              
4   Accounting II    0    0             0         0      1   ESL

Answer 1

让我们使用apply和idxmax：

df['category'] = df.iloc[:,1:].apply(lambda x: x.idxmax(), axis=1)

输出：

       Course_2013  AP  Advanced  Vocational  Basic  ESL  category
0  7th Math Enrich   0         1           0      0    0  Advanced
1  8th Math Enrich   0         1           0      0    0  Advanced
2  8th Science Enr   0         1           0      0    0  Advanced
3     Accounting I   0         0           0      1    0     Basic
4    Accounting II   0         0           0      0    1       ESL