Date:         Wed, 1 May 1996 14:33:24 -0500
Reply-To:     GERALD ZUCKIER <ZUCKIER@CHIME.ORG>
Sender:       "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From:         GERALD ZUCKIER <ZUCKIER@CHIME.ORG>
Subject:      Re: Stratification Index
In-Reply-To:  <"Stratification
              Index*/c=us/admd=attmail/prmd=amex/o=trs/ou=HUB1/ou=snads1/s=Elnagheeb/g=Abdelmoneim/i=H/"@MHS.chime.org>

One way to avoid sorting is if you know all the possible values X can have and
hardcode them into separate counters; i.e.
If X = 1 then count1 = count1 + 1;
If X = 2 then count2 = count2 + 1;
If X = 13.7 then count137 = count137 + 1;
etc.
then just look at the last observation of your output and deal with the
counters.
Otherwise it looks like a case for sorting by X and using first.x and last.x.