topic Creating a Perl Expression in SAS Programming

Creating a Perl Expression

SAS09 — Mon, 05 Sep 2011 18:44:08 GMT

I am a newbie to Perl discussions and hoping that someone can help me with this question. I am trying to identfiy and remove Patient ids in a free form text string using Perl expression - the conditions are as follows:

1. The ids are always 8 bytes and can contains letters(upper or lowercase) and numbers.

2. The ids will always contain at least 1 digit.

Here's the expression I tried to build but I end up picking all 8 letter words. The negated class does not seem to work either.

Here's my code:

id_re=prxparse('s/\b[a-zA-Z0-9]{8}\b/ &id removed& /')

Any ideas - how can find the 8 byte ids.

Creating a Perl Expression

art297 — Mon, 05 Sep 2011 22:42:16 GMT

I'm just starting to learn regular expressions, thus can't be of much help.

I think the expression you want is: ^(?=[a-zA-z0-9]*\d).{8,8}$

That would match an eight character string that contained only letters and or numbers, and contained at least one number.

Unfortunately, I don't know how to implement it.

Re: Creating a Perl Expression

SASJedi — Tue, 06 Sep 2011 00:07:08 GMT

Try this:

 
data ID_REDACTED;
   infile datalines truncover;
   input text1 $100.;
   text2 = prxchange('s/\s\w1\d+\s/ *REDACTED* /', -1, text1);
   datalines;
This patent ID abcdef01 should be removed.
This is NOT a patent ID abcdefgh and should remain.
This is NOT a patent ID 123455 and should remain.
;
run;

Message was edited by: Mark Jordan to improve the Regular Expression

Creating a Perl Expression

art297 — Tue, 06 Sep 2011 00:36:14 GMT

I don't know if the following is quite what you had in mind, but it does appear to eliminate the unwanted IDs:

data have;

length stuff $20;

input;

i=1;

do until (scan(_infile_,i," ") eq "");

stuff=scan(_infile_,i," ");

i+1;

output;

end;

cards;

Now is the time for all good men and women

to come to the GG5567AA aid of their party

Or, was it 4567890 or 45678901 that caused

the problems.

4567890

45678901

ABC4EFGH

;

data want notwant;

set have;

want = PrxChange( 's/^\b(?=[A-Z0-9]*\d).{8,8}\b//io' ,

-1 , Stuff );

if want ne "" then output want;

else output notwant;

run;

Creating a Perl Expression

DF — Tue, 06 Sep 2011 12:26:48 GMT

I find this page to be quite helpful in building/testing regex: http://gskinner.com/RegExr/ (uses Flash).

Sometimes SAS needs a few adjustments to work, either for non-standard stuff or it's own quirks - but it's a good site nonetheless. There's allot of examples, and the tool will help show you the meanings of the different codes.

Re: Creating a Perl Expression

art297 — Tue, 06 Sep 2011 13:21:03 GMT

I crossposted your request on a similar forum (i.e., SAS-L) and a friend/sas/Perl expert (i.e., Toby Dunn) offered the following solution to the problem you raised:

data have;

length stuff $ 80;

input Stuff & ;

cards;

Now is the time for all good men and women

to come to the gh5567AA aid of their party

Or, was it 4567890 or 45678901 that caused

the problems problems.

4567890

45678901

1234_678

1234/678

ABC4EFGH

;

data want;

set Have ;

stuff2 = PrxChange( 's/(?=\b[A-Z0-9]{8}\b)\b[A-Z0-9]*\d[A-Z0-9]*\b//oi' , -1 , Stuff ) ;

run;

Creating a Perl Expression

SAS09 — Tue, 06 Sep 2011 14:38:56 GMT

Thank you so much!! This seems to do it!

Thanks to everyone who replied - I have learnt a lot from all of you suggestions!