EVOLUTION-MANAGER

Edit File: aml.jaro-winkler.inc.php

<?php

/*
 version 1.3

A PHP library implementing Jaro and Jaro-Winkler
distance, measuring similarity between strings.

Theoretical stuff can be found in:
Winkler, W. E. (1999). "The state of record linkage and current
research problems". Statistics of Income Division, Internal Revenue
Service Publication R99/04. http://www.census.gov/srd/papers/pdf/rr99-04.pdf.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at
		your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

===

A big thanks goes out to Pierre Senellart <pierre@senellart.com>
for finding a small bug in the code. Also, thanks goes out to
Debabrata Kar <debakjr@gmail.com> for help in transition to
PHP 5.4+.

function getCommonCharacters( $string1, $string2, $allowedDistance ){

$str1_len = strlen($string1);
	$str2_len = strlen($string2);
	$temp_string2 = $string2;
	 
	$commonCharacters='';

for( $i=0; $i < $str1_len; $i++){

$noMatch = True;

// compare if char does match inside given allowedDistance
		// and if it does add it to commonCharacters
		for( $j= max( 0, $i-$allowedDistance ); $noMatch && $j < min( $i + $allowedDistance + 1, $str2_len ); $j++){
			if( $temp_string2[$j] == $string1[$i] ){
				$noMatch = False;

$commonCharacters .= $string1[$i];

$temp_string2[$j] = '';
			}
		}
	}

return $commonCharacters;
}

function Jaro( $string1, $string2 ){

$str1_len = strlen( $string1 );
	$str2_len = strlen( $string2 );

// theoretical distance
	$distance = (int) floor(min( $str1_len, $str2_len ) / 2.0);

// get common characters
	$commons1 = getCommonCharacters( $string1, $string2, $distance );
	$commons2 = getCommonCharacters( $string2, $string1, $distance );

if( ($commons1_len = strlen( $commons1 )) == 0) return 0;
	if( ($commons2_len = strlen( $commons2 )) == 0) return 0;

// calculate transpositions
	$transpositions = 0;
	$upperBound = min( $commons1_len, $commons2_len );
	for( $i = 0; $i < $upperBound; $i++){
		if( $commons1[$i] != $commons2[$i] ) $transpositions++;
	}
	$transpositions /= 2.0;

// return the Jaro distance
	return ($commons1_len/($str1_len) + $commons2_len/($str2_len) + ($commons1_len - $transpositions)/($commons1_len)) / 3.0;

}

function getPrefixLength( $string1, $string2, $MINPREFIXLENGTH = 4 ){

$n = min( array( $MINPREFIXLENGTH, strlen($string1), strlen($string2) ) );

for($i = 0; $i < $n; $i++){
		if( $string1[$i] != $string2[$i] ){
			// return index of first occurrence of different characters
			return $i;
		}
	}

// first n characters are the same
	return $n;
}

function JaroWinkler($string1, $string2, $PREFIXSCALE = 0.1 ){

$JaroDistance = Jaro( $string1, $string2 );

$prefixLength = getPrefixLength( $string1, $string2 );

return $JaroDistance + $prefixLength * $PREFIXSCALE * (1.0 - $JaroDistance);
}