how to create a copy of first observation of each subject in sas?

[ari]

I have a dataset with 10 observations per subject. I want to create  a copy of the first observation  so that  new datset will contain 11 observations per subject.

Thanks

[RW9 · Accepted solution]

Thats just controlling the output statement:

data want;   /* assumes sorted!! */
  set have;
  by subject;
  if first.subject then do;
    output;
    output;
  end;
  else output;
run;

The above will output two rows if first.subject.  Note needs to be sorted by subject and then the rows in the order you want.