显示大熊猫据帧csv格式

Question

我有一个熊猫数据帧q2看起来像这样：

StudentID  Subjects 
6   323  History 
9   323  Physics 
8   999 Chemistry 
7   999  History 
4   999  Physics 
0  1234 Chemistry 
5  2834  Physics 
1  3455 Chemistry 
2  3455  History 
10  3455 Mathematics 
3  56767 Mathematics 

我想找出哪个学生已经采取哪些课程，并在屏幕上显示出来。

gb = q2.groupby(('StudentID')) 
result = gb['Subjects'].unique() 

c1=pd.DataFrame({'StudentID':result.index, 'Subjects':result.values}) 

c1看起来像这样

StudentID       Subjects 
0  323     [History, Physics] 
1  999  [Chemistry, History, Physics] 
2  1234      [Chemistry] 
3  2834       [Physics] 
4  3455 [Chemistry, History, Mathematics] 
5  56767      [Mathematics] 

然而，理想的输出如下：

323: History, Physics 
999: Chemistry, History, Physics 
1234: Chemistry 
2834: Physics 
3455: Chemistry, History, Mathematics 
56767: Mathematics 

我能做些什么？

Answer 1

我想你可以apply功能join。此外，用于创建DataFrame您可以使用reset_index：

gb = q2.groupby(('StudentID')) 
result = gb['Subjects'].unique() 

c1 = result.reset_index() 

c1.Subjects = c1.Subjects.apply(', '.join) 
print (c1) 
    StudentID       Subjects 
0  323     History, Physics 
1  999  Chemistry, History, Physics 
2  1234      Chemistry 
3  2834       Physics 
4  3455 Chemistry, History, Mathematics 
5  56767      Mathematics 

最后，你可以投列StudentID到str（如果dtype是int）和concanecate在一起：

c1['new'] = c1.StudentID.astype(str) + ':' + c1.Subjects 
print (c1) 
    StudentID       Subjects \ 
0  323     History, Physics 
1  999  Chemistry, History, Physics 
2  1234      Chemistry 
3  2834       Physics 
4  3455 Chemistry, History, Mathematics 
5  56767      Mathematics 

            new 
0     323:History, Physics 
1  999:Chemistry, History, Physics 
2      1234:Chemistry 
3       2834:Physics 
4 3455:Chemistry, History, Mathematics 
5      56767:Mathematics 

此外，如果原始数据可以覆盖，使用：

result = result.index.to_series().astype(str) + ':' + result.apply(', '.join) 
print (result) 
StudentID 
323      323:History, Physics 
999   999:Chemistry, History, Physics 
1234       1234:Chemistry 
2834        2834:Physics 
3455  3455:Chemistry, History, Mathematics 
56767      56767:Mathematics 
dtype: object