How do I achieve such an operation :
import pandas as pd
df = pd.DataFrame({'foo':[1,2,3],'bar_1':[11,21,31],'bar_2':[12,22,32],'bar_3':[13,23,33]})
print(df)
df_pivot = pd.DataFrame({'foo':[1,2,3,1,2,3,1,2,3],'bar_id':['bar_1','bar_1','bar_1','bar_2','bar_2','bar_2','bar_3','bar_3','bar_3'],'bar':[11,21,31,12,22,32,13,23,33]})
print(df_pivot)
giving :
foo bar_1 bar_2 bar_3
0 1 11 12 13
1 2 21 22 23
2 3 31 32 33
foo bar_id bar
0 1 bar_1 11
1 2 bar_1 21
2 3 bar_1 31
3 1 bar_2 12
4 2 bar_2 22
5 3 bar_2 32
6 1 bar_3 13
7 2 bar_3 23
8 3 bar_3 33
I want to keep (and repeat all the foo columns) but separate the bar ones (and keeping a trace of it with bar_id).
I looked at pandas.pivot, but I cannot find a way.
Thanks :)
