data null_1(drop =_:)
null_2(keep =_x rename =(_x =n_obs));
set rate_all2nonRrr1;
by clnt_no acct_ref_no;
n_obs ++1;
_qtr=qtr(qtr_dt)+year(qtr_dt)*4;
length _obs_need $32;
retain _maxcon _obs_need;
*** Order consecutive records;
_lagqtr=lag(_qtr);
if first.acct_ref_no then call missing(_obs_need,_maxcon,_lagqtr,_con);
if _qtr-_lagqtr =1 then _con +1;
else _con =1;
*** Get the n_obs for the first 3(or 2) consecutive records.;
if _con =2 then do;
if missing(_maxcon) then _obs_need=catx(",",n_obs-1,n_obs);
if missing(_maxcon) then _maxcon=2;
end;
if _con=3 then do;
if _maxcon ne 3 then _obs_need=catx(",",n_obs-2,n_obs-1,n_obs);
_maxcon=3;
end;
output null_1;
*** Get the needed observations;
if last.acct_ref_no then do i =1 by 1 while (scan(_obs_need,i,',') ^=' ');
_x =input(scan(_obs_need,i,','), best.);
output null_2;
end;
run;
proc sql;
create table null_3 as
select a.*
from
null_1 as a
inner join
null_2 as b
on a.n_obs =b.n_obs;
quit;