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MathGroup Archive 2002

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Re: Pattern matching

  • To: mathgroup at
  • Subject: [mg33965] Re: [mg33912] Pattern matching
  • From: BobHanlon at
  • Date: Wed, 24 Apr 2002 01:23:02 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

In a message dated 4/23/02 9:39:43 AM, leary at writes:

>Can you help me please - there must be a simple solution to this problem,
>but I can't find it.
> From a list of character strings and a list of templates,  I need to 
>produce a list of all strings that match any of the templates.  For example:
>listData={"18K0F3C--" , "2K40GXX--" , "400HGXX--" , "5M00G1F--" , 
>listTemplates={"???H?????" , "???K?????"}
>In the templates, ? is a wild-card that represents a single character.
>The data strings contain only alpha-numeric characters and hyphens - no
>other characters.
>There are no special requirements for the result:  duplication and random
>order are acceptable.
>I searched the MathGroup archive and found a very useful function that
>exactly what I want, but it works only on individual strings, not lists
>strings (msg00051):
>QMMatchQ[s_String, p_String] := MatchQ[Characters[s], Characters[p] /.
>-> _ ]
>I tried to use it in the following way, but the result is a list of the
>matching templates, not the matching strings :
>QMMatchQ[s_String, p_String] := MatchQ[Characters[s], Characters[p] /.
>-> _ ]
>SetOptions[Intersection, SameTest -> (QMMatchQ[#1,#2]& )];
>It ought to be a small step from there to the result that I need, but I
>can't find a simple solution.
>One alternative approach would be a Do loop:

>This works but seems to be very slow for large lists.  In the real case,
>listData can be very large - up to 250,000 elements - and the Do loop 
>approach doesn't seem to be optimum.




QMMatchQ[s_String,{p__String}]:=Or @@
              Characters[#]/."?"->_]& /@ {p});


{"400HGXX--", "960KG1D--"}



{"400HGXX--", "960KG1D--"}

Bob Hanlon
Chantilly, VA  USA

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