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Re^3: approximate regular expression

by jandrew (Hermit)
on Mar 23, 2012 at 22:00 UTC ( #961321=note: print w/ replies, xml ) Need Help??


in reply to Re^2: approximate regular expression
in thread approximate regular expression

Marshall thank you for your feedback

Honestly I don't have a good handle on what perl "with the flow" really means. I guess I was responding to jrblas's request regarding fuzzy regex's. And by that I mean that fuzzy regex's mostly land in the TODO bucket of the regex wizards from what I have read. I do say that as a regex weakling so there may be something out there that I don't know about. Specifically Marpa seems to promise some alternatives but that is even farther beyond my current grasp.

With that said I have to confess to laziness in calculating the match score. As a guess the original question appears to fall in the bio-perl realm which upon further study would also benefit from regex Look-Around add-ons. So I offer the following in penance.

#! C:/Perl/bin/perl use strict; use warnings; use Smart::Comments '###'; $| = 1; my $pattern = "JEJE"; my $string = "EJKJUJHJDJEJEJEDEJOJOJJJAHJHJSHJEFEJUJEJUJKIJS"; my $test_regex = _build_test( $pattern ); ### $test_regex for my $x ( 0..((length $string) - (length$pattern)) ){ my $test_string = substr( $string, $x, length$pattern ); my $score = _test_for_score( 1, $test_string, $test_regex ); #### $test_string #### <where> - returned: $score if( $score and $score >= 2 ){ print "String: $test_string, position: $x, score: $score\n"; } } sub _test_for_score{ my ( $min_score, $test_string, $test_regex ) = @_; my $score = undef; my $x = length $test_string; for my $regex ( reverse @$test_regex ){ #### $x #### $regex if( $test_string =~ /$regex/ ){ $score = $x; last; } $x--; } return $score; } sub _build_test{ my ( $pattern ) = @_; my $test_reg; my $pattern_reg = [ split //, $pattern ]; for my $substitutions ( 0..(length $pattern) ){ my $return_reg = _build_score_reg( $substitutions, $pattern_re +g ); my $string = join '|', @$return_reg; # add the look ahead / look behind assertions to $string here +... $test_reg->[ (length $pattern) - $substitutions ] = qr/$string +/; #### $test_reg } return $test_reg; } # This is the fuzzy regex build part sub _build_score_reg{ my ( $score, $pattern_reg, $finsished_pos ) = @_; $finsished_pos ||= 0; #### <where> - reached _build_score_reg #### <where> - score : $score #### <where> - pattern : $pattern_reg #### <where> - complete: $finsished_pos my $sub_reg; if( $score == 0 ){ $sub_reg->[0] = join '', @$pattern_reg; }else{ for my $x ( $finsished_pos..$#$pattern_reg ){ #### <where> - running position: $x last if ( $#$pattern_reg - $score + 1 ) < $x; my $copy_reg = [ @$pattern_reg ];# To not overwrite the pa +ssed reference $copy_reg->[$x] = '.'; #### $copy_reg #### $finsished_pos my $recursive_reg = _build_score_reg( $score - 1, $copy_re +g, $x + 1 ); #### $recursive_reg push @$sub_reg, ( join '|', @$recursive_reg ); #### $sub_reg } } #### $sub_reg return $sub_reg; }
With the Results
### $test_regex: [ ### qr/(?-xism:....)/, ### qr/(?-xism:...E|..J.|.E..|J...)/, ### qr/(?-xism:..JE|.E.E|.EJ.|J..E|J.J.|JE..)/, ### qr/(?-xism:.EJE|J.JE|JE.E|JEJ.)/, ### qr/(?-xism:JEJE)/ ### ] String: JKJU, position: 1, score: 2 String: JUJH, position: 3, score: 2 String: JHJD, position: 5, score: 2 String: JDJE, position: 7, score: 3 String: JEJE, position: 9, score: 4 String: JEJE, position: 11, score: 4 String: JEDE, position: 13, score: 3 String: DEJO, position: 15, score: 2 String: JOJO, position: 17, score: 2 String: JOJJ, position: 19, score: 2 String: JJJA, position: 21, score: 2 String: JHJS, position: 26, score: 2 String: SHJE, position: 29, score: 2 String: JEFE, position: 31, score: 3 String: FEJU, position: 33, score: 2 String: JUJE, position: 35, score: 3 String: JEJU, position: 37, score: 3 String: JUJK, position: 39, score: 2


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