从段落中找到匹配词的最有效方法

Question

我有一个段落，我必须针对不同的关键字进行解析。例如，段落：

"I want to make a change in the world. Want to make it a better place to live. Peace, Love and Harmony. It is all life is all about. We can make our world a good place to live"

我的关键词是

"world"、"earth"、"place"

我应该在比赛的时候报告，报告多少次。

输出应该是：

"world" 2 次和 "place" 1 次

目前，我只是将段落字符串转换为字符数组，然后将每个关键字与所有数组内容进行匹配。这是在浪费我的资源。请指导我一个有效的方法。（我正在使用PHP）

Answer 1

我会用preg_match_all()。这是它在您的代码中的样子。实际函数 returns 找到的项目数，但 $matches 数组将保存结果：

<?php
$string = "world";

$paragraph = "I want to make a change in the world. Want to make it a better place to live. Peace, Love and Harmony. It is all life is all about. We can make our world a good place to live";

if (preg_match_all($string, $paragraph, &$matches)) {
  echo 'world'.count($matches[0]) . "times";
}else {
  echo "match NOT found";
}
?>

Answer 2

<?php
    Function woohoo($terms, $para) {
     $result =""; 
     foreach ($terms as $keyword) {
        $cnt = substr_count($para, $keyword);
        if ($cnt) {
          $result .= $keyword. " found ".$cnt." times<br>";
        }
      }
      return $result;
    }
    $terms = array('world', 'earth', 'place');
    $para = "I want to make a change in the world. Want to make it a better place to live.";
    $r = woohoo($terms, $para);
    echo($r);
?>

Answer 3

正如@CasimiretHippolyte 评论的那样，正则表达式是更好的方法，因为 word boundaries can be used. Further caseless matching is possible using the i flag. Use with preg_match_all return 值：

Returns the number of full pattern matches (which might be zero), or FALSE if an error occurred.

匹配一个词的模式是：/\bword\b/i。生成一个数组，其中键是来自搜索 $words 的词值，值是映射的词数，即 preg_match_all returns:

$words = array("earth", "world", "place", "foo");

$str = "at Earth Hour the world-lights go out and make every place on the world dark";

$res = array_combine($words, array_map( function($w) USE (&$str) { return
       preg_match_all('/\b'.preg_quote($w,'/').'\b/i', $str); }, $words));

print_r($res); test at eval.in 输出到：

Array ( [earth] => 1 [world] => 2 [place] => 1 [foo] => 0 )

使用了preg_quote来转义不必要的单词，如果你知道的话，它们不包含任何特殊的。对于使用 array_combine PHP 的内联匿名函数，需要 5.3.

从段落中找到匹配词的最有效方法

Most efficient way to find matching words from paragraph

php

regex

algorithm

compare

pattern-matching