Date:         Mon, 27 Nov 2006 14:09:27 -0500
Reply-To:     Jack Clark <JClark@CHPDM.UMBC.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Jack Clark <JClark@CHPDM.UMBC.EDU>
Subject:      Re: is there another way doing it
Comments: To: SAS_learner <proccontents@GMAIL.COM>
Content-Type: text/plain

SAS_learner,

Another option is the SELECT statement.  It is usually recommended as more
efficient when you have more than a handful of IF-THEN choices.  I don't
know if that holds true when the select is based on the value of more than
one variable.

One thing you could do for improved efficiency to the example you provided
is add the ELSE statement to all IF-THEN checks after the first one.  Each
IF-THEN you provided is mutually exclusive (based on the values of parnam1c
you are checking).  Therefore, once an observation meets one of the IF-THEN
conditions, there is no need to check the others below it.

  if parnam1c='BAS'    and upcase(preunt1c)='%'         and (
LABRSL1N>  6) then output;
ELSE  if parnam1c='EOS'    and upcase(preunt1c)='%'       and (
LABRSL1N> 10) then output;
ELSE  if parnam1c='HGB'    and upcase(preunt1c)='G/L'     and (LABRSL1N<100
or
LABRSL1N>200) then output;
ELSE  if parnam1c='HCT'    and upcase(preunt1c)='1'       and (LABRSL1N<0.3
or
LABRSL1N>0.6) then output;
ELSE  if parnam1c='LYM'    and upcase(preunt1c)='%'       and (LABRSL1N<10
or
LABRSL1N> 60) then output;
ELSE  if parnam1c='MON'    and upcase(preunt1c)='%'       and (
LABRSL1N> 20) then output;


I was taught to order the IF-THEN choices in the program in the order in
which they most likely will occur in your data (if you have an estimate of
this ahead of time).  So if you know that 70% of your input observations
have a value of 'BAS' for parnam1c, you would put that check first, and so
on.  If you were to put the check for 'BAS' last, you would have to go
through each of the IF-THEN-ELSE statements for 70% of your observations.



Jack Clark
Research Analyst
Center for Health Program Development and Management
University of Maryland, Baltimore County


-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
SAS_learner
Sent: Monday, November 27, 2006 12:26 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: is there another way doing it

Hello guys for a listing I need to do something like this for couple of
different values of Parnam1c, What I am looking is there a better way to dot
it or is this only way to do it

  if parnam1c='BAS'    and upcase(preunt1c)='%'         and (
LABRSL1N>  6) then output;
  if parnam1c='EOS'    and upcase(preunt1c)='%'       and (
LABRSL1N> 10) then output;
  if parnam1c='HGB'    and upcase(preunt1c)='G/L'     and (LABRSL1N<100  or
LABRSL1N>200) then output;
  if parnam1c='HCT'    and upcase(preunt1c)='1'       and (LABRSL1N<0.3  or
LABRSL1N>0.6) then output;
  if parnam1c='LYM'    and upcase(preunt1c)='%'       and (LABRSL1N<10   or
LABRSL1N> 60) then output;
  if parnam1c='MON'    and upcase(preunt1c)='%'       and (
LABRSL1N> 20) then output;

thanks