Beefy Boxes and Bandwidth Generously Provided by pair Networks Cowboy Neal with Hat
more useful options
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

Hi, I find myself writting another app this month that requires matching against list of patterns, what I did the last time is:

#... while ($line=<>) { #... foreach $user (keys(%$users)) { my $pattern=$user->{'Pattern'}; if ($line=~/$pattern/i) { print STDERR "Great, we found pattern $pattern!\n"; } }; };

This is straitghtforwad and it works.

The problem is that it grows roughly N**2, (because there is relation between number of lines to parse, and amount of possible patterns).

UPDATE: I keep patterns in hashref because the whole point of this excercise is to figure out WHICH regexp matched. ORing patterns together might be fine if I knew how to figure out which patter from such ORed pattern matched exactly.

What do people do with such problems? Is it possible to optimise this? ( for example, group patterns into eee...groups based on common prefix or something common, or maybe preprocess those lines, split sentences into functional parts .. )

This seems like rather common task, are there any smart (or at least working) solutions?


In reply to Matching against list of patterns by Eyck

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others chilling in the Monastery: (8)
    As of 2014-04-17 07:19 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      April first is:







      Results (440 votes), past polls