How to change column wise data into row wise in excel using python (consider records in Millions)

Question

Input

StuId  Name     Subject
1      Adam      French
1      Adam      English 
1      Adam      Science
2      Jon        Maths
2      Jon        French

Output expected:

 StuId     Name       Subjects
  1        Adam       French    English   Science
  2         Jon       Maths     French

Thanks

In order to kick start a meaningful conversation, you need to specify how you parse this data and what your internal structure is. — Bogdan Ionitza, Jul 25 '22 at 09:10

score 2 · Answer 1 · answered Jul 25 '22 at 09:10

IIUC, You can use pandas.pivot_table with aggfunc=' '.join.

df = df.pivot_table(index=['StuId','Name'], values=['Subject'], 
                    aggfunc=' '.join).reset_index()
print(df)

   StuId  Name                  Subject
0      1  Adam  French English  Science
1      2   Jon             Maths French

score 0 · Answer 2 · answered Jul 25 '22 at 09:10

0

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answered Jul 25 '22 at 09:10

Baba Ranjith

score 0 · Answer 3 · answered Jul 25 '22 at 09:14

You can group by the other columns and aggregate the subjects using a list -

 df.groupby(['StuId', 'Name']).agg(lambda x: ' '.join(list(x)))

Output

                           Subject
StuId Name                        
1     Adam  French English Science
2     Jon             Maths French

3 Answers3