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My data is the following:
1 2 3
1995 33 44 77
1996 22 55 88
1997 11 66 99
how can I have the output like this?
How could I have the output like this?
code year value
1 1995 33
1 1996 22
1 1997 11
2 1995 44
2 1996 55
2 1997 66
3 1995 77
3 1996 88
3 1997 99
thank you very much for your help!