How can I convert yearly data columns into to yearly data rows based in ID - Pandas Python [duplicate]

This is wide_to_long

pd.wide_to_long(df,['t','l'],i=['id1','id2'],j='drop').reset_index(level=[0,1])
Out[52]: 
      id1  id2  t  l
drop                
1       1    2  a  b
2       1    2  c  d
1       3    4  g  h
2       3    4  i  j

You can use melt twice here and after that concat them to get desired output:

t = d.melt(id_vars=['id1', 'id2'], value_vars=['t1', 't2'], value_name='tz').drop('variable', axis=1)
l = d.melt(id_vars=['id1', 'id2'], value_vars=['l1', 'l2'], value_name='lz').iloc[:, -1:]

df = pd.concat([t, l], axis=1).sort_values('id1')

Output

print(df)
   id1  id2 tz lz
0    1    2  a  b
2    1    2  c  d
1    3    4  g  h
3    3    4  i  j