Correction : st: : Request code simplification

[Michael Stewart <michaelstewartresearch@gmail.com>]

Sorry for the typos  in the previous post(they showed up as I  was
removing any patient  identifiers from the dataset) , I am posting the
corrected request again

Hi,
I am  working on a data set with thousands of patients( and multiple
records per patient) and I am trying to identify pateints with any
transplant(could undergo liver, kidney, intestine etc) . I was
wondering if we could simplify my  code as my laptop is freezing with
the following set of commands.


Here the goal is find patients who has type_of_visit[1]=="first_
clinic_visit" & any other type_of_visit is ""(after the records are
sorted by pat_id and visit_date)

My code :

bysort pat-id (visit_date):carryforward type_of_visit,gen(v)
bysort pat-id (visit_date):gen x=v[1]==v[_n]
bysort pat-id (visit_date):egen z=sum(x)
bysort pat-id (visit_date):egen zz=count(x)
gen y= z< zz



The dataset format is as follows.

pat-id     visit_date     type_of_visit
-------------------------------------------------------
xxx      09/01/2003      first_clinic_visit
xxx      09/15/2003
                .
                .
                .
                .
XXX      12/12/2003
XXX      2/04/2004       liver_transplant
yyy      01/01/2004      first_clinic_visit
yyy      02/02/2005
                 .
                  .
yyy     01/03/2008      intestine_transplant
zzz      05/01/2010     first_clinic_visit
zzz     05/03/2011
                  .
                  .
                  .
                  .
------------------------------------------------------------

As always, thanks a lot for your time
Thank you ,
Yours Sincerely,
Mike.
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