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Date:   Thu, 10 Mar 2011 14:19:05 -0800
Reply-To:   "Sprague, Webb (OFM)" <Webb.Sprague@OFM.WA.GOV>
Sender:   "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:   "Sprague, Webb (OFM)" <Webb.Sprague@OFM.WA.GOV>
Subject:   Re: "Unpacking" variable in a datastep into a "macro function"
Comments:   To: toby dunn <tobydunn@HOTMAIL.COM>
In-Reply-To:   A<BLU152-w3022409EA1EF0525C12DB6DEC80@phx.gbl>
Content-Type:   text/plain; charset="us-ascii"

I am not sure why you think I needed help with RE's (my question was about macros) but for the sake of all our edification, I have replied below.

Note that these RE's are the last attempt to filter out a housing type when other, more deterministic, approaches have already failed. So I am shooting for fuzzy.

> %SysFunc( PRXMatch( /...../ , <VarName> ) ) > > Only works in 9.2 and higher, in prior version the PrxMatch function > when used in teh macro facility assumed the pattern was already > precompiled via a PRXparse function call.

I couldnt get it to work, and decided to go with a simpler approach.

> /(RE*MO*DE*L)|(A*LTE*RA*T[IO]*N*)|(ADDI*T[IO]*)|(REHAB)|(REROOF)|(REMOV > E)/ > > Id loose the * and repace it with a +, Im pretty sure the 'E' and 'O'

No, the * is what I want, because often when people abbreviate they leave out the vowels. RMDL => Remodel. REEMODEL => Remodel. But RAMODIL probably not Remodel.

> in RE*MO*DE*L for example aren't optional. > Rather the poster is wanting atleast one or more occurances of these. > If it is optional then I would use the ?. > The * says 0 or more, which more often than not is not exactly what the > coder wants. In short the * is one > of the most over used and misunderstood Quantifiers.

Misunderstood by some people, but not by me. ;)

> Depending on how many alternatives are to searched for, I would be > tempted to loose the capturing parens or use > non-capturing parens, and if there is to be a preference which one is > to be matched first I would look at the order > the alternatives are specified in the pattern.

Why lose the parens? I thought you needed them with alteration "|". If not, yes they should go, as I am not substituing them in. putting most frequent first is a good idea.

> If distinct words are to be matched and not parts of a word I would add > the \b word boundary metasequences.

Yeah, I know how that works too. I compress, delete punctuation, and thus \b doesn't apply.

> As it is now it could match REMODEL, NONREMODEL, REMODELED.... you get > the idea.

Thats what we want. I am glad you confirm. ;) NONREMODELBUTREALLYSFR would fall through the cracks, but it is unlikely.

> If there is only one word and not a bunch of words in the Target String > I would add the ^ and $ line anchors to allow > the Reg Ex engine optmizer to take over.

Again, I am looking for the words anywhere in the string, so I don't use anchors (except once).

> I definitly add the /o pattern modifier to the RegEx pattern.

I will look into that

> Finally, it may be faster to break the alternatives down into a series > of PrxMatch function calls rather than one big > honker pattern and function call. This however, takes knowing ones > data, what is to and not to be matched.

Actually, I know my data fairly well, ... thanks. I keep the REs as big honkers because lots of different input (SFR, SINGLEFAM, SINGFAM, etc => SFR) all yield the same result, and I like the way it is organized this way. Like you say, the most common in the bunch near the front would be best.


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