*********************************************;
* Clinical data set questions:              *;
* VI. Data Processing                       *;
*********************************************;

options linesize=min;

libname mydir 'c:\My Documents\My SAS Files\sasmanual\data';

data bygroup;
set mydir.clinical;
run;

proc sort data=bygroup;
by prim_dx;
run;

data bygroup;
set bygroup;
by prim_dx;
first_prim_dx=first.prim_dx;
last_prim_dx=last.prim_dx;
run;

proc print data=bygroup;
var id gender dob prim_dx first_prim_dx last_prim_dx;
format prim_dx sec_dx $dxcodes.
       dob visit mmddyy8.
       gender $gender.
       vitamins pregnant $yesno.;
title 'BY-groups by Primary Diagnosis'; 
run;

proc sort data=bygroup;
by prim_dx;
run;

data c_bygroup;
set bygroup;
retain count;
if first_prim_dx then do;
count=0;
end;
count=count+1;
run;

proc print data=c_bygroup;
format prim_dx sec_dx $dxcodes.
       dob visit mmddyy8.
       gender $gender.
       vitamins pregnant $yesno.; 
title 'Count of BY-groups';
run;