最小编辑距离算法比较文本异同 Levenshtein Distance。引用自https://code.google.com/archive/p/clamdemo/downloads

MinumDistance.php

<?php
/***************************************************************************
 * 
 * Copyright (c) 2011 log4myself.com, Inc. All Rights Reserved
 * 
 **************************************************************************/
 
 
 
/**
 * @file MinumDistance.php
 * @author caojiandong(neu.loner@gmail.com)
 * @date 2011/11/24 16:03:59
 * @brief  计算最小编辑距离类，返回输出过程
 *  
 **/

class MinumDistance {


    /**
     * 计算编辑距离的核心算法
     *
     * return array(
     *   'distance' =>   最小编辑距离
     *   'progress' =>   编辑过程
     * )
     **/

    const MAX = 100000;
    private function execute($src,$tgt){

        $progress = array();
        $m = count($src);
        $n = count($tgt);
        $d[self::MAX][self::MAX] = array();
        $type[self::MAX][self::MAX] = array();
        $back[self::MAX][self::MAX][2] = array();

        $i = 0;
        $j = 0;
        $backi = 0;
        $backj = 0;
        $backtype = 0;
        for($i = 0;$i <= $m;$i ++)
            $d[$i][0] = $i;

        for($j = 0;$j <= $n;$j ++)
            $d[0][$j] = $j;

        for($j = 1;$j <= $n;$j ++){
            for($i = 1;$i <= $m;$i ++){
                if($src[$i-1] == $tgt[$j-1]){
                    $d[$i][$j] = $d[$i-1][$j-1];
                    $back[$i][$j][0] = $i-1;
                    $back[$i][$j][1] = $j-1;
                    $type[$i][$j] = 0;
                }else{
                    $d[$i][$j] = $d[$i-1][$j]+1;
                    $back[$i][$j][0] = $i-1;
                    $back[$i][$j][1] = $j;
                    $type[$i][$j] = 2;
                    if($d[$i][$j]>$d[$i][$j-1]+1){
                        $d[$i][$j] = $d[$i][$j-1]+1;
                        $back[$i][$j][0] = $i;
                        $back[$i][$j][1] = $j-1;
                        $type[$i][$j] = 1;
                    }
                    if($d[$i][$j]>$d[$i-1][$j-1]+1){
                        $d[$i][$j] = $d[$i-1][$j-1]+1;
                        $back[$i][$j][0] = $i-1;
                        $back[$i][$j][1] = $j-1;
                        $type[$i][$j] = 3;
                    }
                }
            }
        }
        $backi = $m;
        $backj = $n;
        while($backi && $backj){

            $backtype = $type[$backi][$backj];
            switch($backtype){
            case 0:
                $progress['copy'][] = array($backi-1,$backj-1);
                break;
            case 1:
                $progress['del'][] = $backj-1;
                break;
            case 2:
                $progress['insert'][] = $backi-1;
                break;
            case 3:
                $progress['replace'][] = array($backi-1,$backj-1);
                break;
            }
            $i = $back[$backi][$backj][0];
            $j = $back[$backi][$backj][1];
            $backi = $i;
            $backj = $j;
        }
        return array(
           'distance' => $d[$m][$n],
           'progress' => $progress,
            );
    }

    public function getMinumDistance($arrSrc,$arrTgt){
	
	//接受string参数，如果是string,则进行stringToarray的转化
        if(is_string($arrSrc) && is_string($arrTgt)){
            $arrSrc = $this->getArrayFromString($arrSrc);
            $arrTgt = $this->getArrayFromString($arrTgt);
        }

        if((!is_string($arrSrc) || !is_string($arrTgt)) &&
            (!is_array($arrSrc) || !is_array($arrTgt)))
           return false;

        return $this->execute($arrSrc,$arrTgt);
    }

    public function __construct(){
    }

	//将文本分字成数组
    private function getArrayFromString($str){
        $result = array();
        $strLen = mb_strlen($str,"UTF8");
        $i = 0;
        for($i = 0; $i < $strLen ; $i ++){
            $result[]  = mb_substr($str,$i,1);
        }
        return $result;
    }


}


//显示不同之处的示例代码
$src = 'hello world 打倒旧世界';
$tgt = 'heelo wolrd!开创新世界';

$md = new MinumDistance();
$result = $md->getMinumDistance($src, $tgt);

$p = $result['progress'];
$index = 0;

$srcProgress = $tgtProgress = [];
foreach ($p['copy'] as $value) {
    if ($value[0] == $value[1]) {
        $srcProgress[] = $value[0];
        $tgtProgress[] = $value[1];
    }
}

echo hightlight($src, $srcProgress). '<br />';
echo hightlight($tgt, $tgtProgress). '<br />';

function hightlight($str, $progress) {
    $srcArr = preg_split('//u', $str, null, PREG_SPLIT_NO_EMPTY);

    $j = count($srcArr);
    foreach ($progress as $i) {
        if ($i < $j) {
            for ($k=$i+1; $k < $j; $k++) { 
                $srcArr[$k] = '<span style="color:red;">'.$srcArr[$k].'</span>';
            }
        }
        $j = $i;
    }
    return implode('', $srcArr);
}



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