create a iteration in a group

cecily — Fri, 03 Jul 2015 16:11:37 GMT

Here is the original data

class

And I would like to create a new variable which counts the number in each group.

class count

1 1

1 2

1 3

1 4

1 5

1 6

3 1

3 2

3 3

4 1

4 2

4 3

4 4

I think I may use first. last.variable to get the count.But I still don't know how to write the code...Could you help me?

Re: create a iteration in a group

Reeza — Fri, 03 Jul 2015 17:54:43 GMT

cecily — Fri, 03 Jul 2015 19:37:47 GMT

thank you very much