how to create a sequence number

[desireatem]

Hello 

I have this data set;

data A;

input id  admit;

cards;

001        2001

001        2002

001        2002

002        2001

002        2001

003        2002

;

run;

I wish to create data B from A

data B;

input id  admit SeqN ;

cards;

001        2001     1

001        2002     2

001        2002     3

002        2001     1

002        2001     2

003        2002     1

;

run;

I want to create a SeqN from Data A.

[Astounding · Accepted solution]

As long as your data set is sorted by ID:

data want;

set have;

by id;

if first.id then SeqN=1;

else SeqN + 1;

run;

[desireatem]

Thank you!!!

[RW9]

Good use for ifn()?

data want;
  set have;
  by id;
  seqn=ifn(first.id,1,seqn+1);
run;