Date:         Fri, 7 May 2004 13:44:29 -0700
Reply-To:     cassell.david@EPAMAIL.EPA.GOV
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "David L. Cassell" <cassell.david@EPAMAIL.EPA.GOV>
Subject:      Re: In Operator with numbers
Content-type: text/plain; charset=US-ASCII

"Choate, Paul@DDS" <pchoate@DDS.CA.GOV> quoted the legendary P. Dorfman:
> A related snipet from a recent Paul Dorfman post:
> ===================================
> I find IN-lists with myriads of quoted character values, such as
>
> if v1 in ('123' '234' '345' '456' '567' '678' '789' '890') then...
>
> inconvenient and making the program hard to read (If you want a real
example
> of Ian-invented term "wallpaper", that is it). The most SAS-centric
approach
> would be, as others have pointed out, to store the values in a file
and then
>
> reading the latter to either create a quoted IN-list as a value
assigned to
> a macro variable via SQL, or (which I would prefer) to create a
format. This
> would separate the code (what to do with data) from the hard-coded
values
> (the data themselves).
>
> However, even if you feel you must use a hard-coded list, there is a
way to
> make it more tidy than ibid.:
>
> if index (v1, '123 234 345 456 567 678 789 890') then...
>
> Not only you rid the code from the gazillion of quotes, it will run
more
> rapidly, too. SAS string-searching functions algorithms quite faster
than
> the linear search used by the IN operator...
> ===================================

The suggestion by Paul (Dorfman) has one major problem.  Which I had the
misfortune to encounter while error-checking some data from a GIS
database.
I was looking for character categories which would seem to fit into the
above strategy.  But what happens when you use the above line and one
incorrect
string looks like:

4 3

Uh-oh.  That was just accepted as legit by the INDEX() approach above.
You
have to make sure that chunks of your index string cannot be illegal
character
strings.  The first version (if v1 in ...) doesn't have this problem.
If you
can't bear the shame of wallpaper in your code, then check your variable
using
a format instead.

HTH,
David
--
David Cassell, CSC
Cassell.David@epa.gov
Senior computing specialist
mathematical statistician