Date:         Tue, 13 Aug 2002 16:26:53 +0100
Reply-To:     Peter Crawford <peter.crawford@DB.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Peter Crawford <peter.crawford@DB.COM>
Subject:      Re: indexW() behaviour
Comments: To: Ian Whitlock <WHITLOI1@WESTAT.com>
Content-type: text/plain; charset=iso-8859-1

Ian
thank you for the input.
When you say
"I would much rather have a default of word boundaries."
I'm not quite sure, except that your example appears to
use a comma delimiter. Whereas the word boundary
expected by indexW() is blank.
I agree that this is worthy of a third parameter, like the scan() delimiters.
... but see later

"DSD type" respect by scan() for delimiters quoted in data
becomes available in v9.0 but as the new function
>SCANQ function, version 9 and later                  Oct 23, 2001
>
>Returns the nth "word" from a character expression, ignoring
>delimiters inside quotation marks.
see ftp://ftp.sas.com/pub/neural/functions/scanq.txt

In the parent of this unofficial description/documentation,
ftp://ftp.sas.com/pub/neural/functions.html
it declares
INDEXW has an optional third argument to specify delimiters

So, it seems we should have this improvement to indexW()
"real soon now"




Kind Regards
Peter Crawford



Datum:         13/08/2002 16:10
An:            Peter Crawford/Zentrale/DeuBaExt@Zentrale
               SAS-L@LISTSERV.UGA.EDU



Betreff:       RE: indexW() behaviour
Nachrichtentext:

Peter,

I am not surprised.  A blank is not a word, in my book,  so I would not
expect it to found.  On the other hand, I did find the following log rather
disturbing, albeit documented.  I would much rather have a default of word
boundaries.  And while I am thinking about it, SCAN should have another
parameter, so that it could behave like DSD on INFILE statements.  Of
course, the default value should be to behave as it does now.

12   data _null_ ;
13
14      x = "abc,def@" ;
15      abc = indexw(x, "abc") ;
16      comma = indexw(x,",") ;
17      def = indexw(x,"def") ;
18      at = indexw(x,"@") ;
19      put _all_ ;
20   run ;

x=abc,def@ abc=0 comma=0 def=0 at=0 _ERROR_=0 _N_=1
NOTE: DATA statement used:
     real time           0.05 seconds

IanWhitlock@westat.com

-----Original Message-----
From: Peter Crawford [mailto:peter.crawford@DB.COM]
Sent: Tuesday, August 13, 2002 10:35 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: indexW() behaviour


Hi there,
I want your opinion !

I just discovered a feature of indexW()
Unlike indexC() and index() with trim(), indexW()
never "finds" blanks, as in the third value for NAME below.
This is behaviour I would want, but hadn't expected !
Now I have to wonder, .....
A) should I _expect_ indexW() to  "never find blank"  ????
or
B) should I prepare code to test blank explicitly  ????
in case a future release _upgrades_ the function
behaviour  ??????????????????
  (like function quote() was "upgraded" in v7
   no longer does it trim() before quoting ! )

I tend to favor B) above, because it is obvious to a
programmer who is less familiar with the app./code

BUT if you would not expect indexW() to "find a blank"
then I can adopt policy A).....
..... which might have a performance benefit over a few
billion iterations!!


1048  data _null_;
1049    names = 'AB  C D' ;
1050    do name = 'PQD', 'C', ' ' ;
1051     foundw = indexW( names, name );
1052     foundC = indexC( names, name );
1053     found   = index( names, name );
1054     foundt  = index( names, trim(name) );
1055     put name= @11 foundW= foundC= found= foundt= ;
1056   end;
1057  run;

name=PQD  foundw=0 foundC=7 found=0 foundt=0
name=C    foundw=5 foundC=3 found=0 foundt=5
name=     foundw=0 foundC=3 found=0 foundt=3
NOTE: DATA statement used:





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