I have a dataset in the below format:
ID A B C D
1 x x x x
2 x x x x
3 x x x x
4 x x x x
I want to convert it into a format where ID is duplicated with the values of the rows, e.g. to look something like below:
ID Letter Value
1 A x
1 B x
1 C x
1 D x
2 A x
2 B x
2 C x
2 D X
and so on....
Many thanks in advance.