抓取给定关键字前后的x个单词数？

Question

如何在PHP中的字符串中获取给定关键字之前和之后的单词数量[x]？我试图从为关键字定制的mysql查询结果标记为片段。

Answer 1

$string = 'This is a test string to see how to grab words from an arbitrary sentence. It\'s a little hacky (as you can see from the results) - but generally speaking, it works.'; 

echo $string,'<br />'; 

function getWords($string,$word,$before=0,$after=0) { 
    $stringWords = str_word_count($string,1); 
    $myWordPos = array_search($word,$stringWords); 

    if (($myWordPos-$before) < 0) 
     $before = $myWordPos; 
    return array_slice($stringWords,$myWordPos-$before,$before+$after+1); 
} 

var_dump(getWords($string,'test',2,1)); 
echo '<br />'; 
var_dump(getWords($string,'this',2,1)); 
echo '<br />'; 
var_dump(getWords($string,'sentence',1,3)); 
echo '<br />'; 
var_dump(getWords($string,'little',2,2)); 
echo '<br />'; 
var_dump(getWords($string,'you',2,2)); 
echo '<br />'; 
var_dump(getWords($string,'results',2,2)); 
echo '<br />'; 
var_dump(getWords($string,'works',2,2)); 

echo '<hr />'; 


function getWords2($string,$word,$before=0,$after=0) { 
    $stringWords = str_word_count($string,1); 
    $myWordPos = array_search($word,$stringWords); 
    $stringWordsPos = array_keys(str_word_count($string,2)); 

    if (($myWordPos+$after) >= count($stringWords)) 
     $after = count($stringWords) - $myWordPos - 1; 
    $startPos = $stringWordsPos[$myWordPos-$before]; 
    $endPos = $stringWordsPos[$myWordPos+$after] + strlen($stringWords[$myWordPos+$after]); 

    return substr($string,$startPos,$endPos-$startPos); 
} 

echo '[',getWords2($string,'test',2,1),']<br />'; 
echo '[',getWords2($string,'this',2,1),']<br />'; 
echo '[',getWords2($string,'sentence',1,3),']<br />'; 
echo '[',getWords2($string,'little',2,2),']<br />'; 
echo '[',getWords2($string,'you',2,2),']<br />'; 
echo '[',getWords2($string,'results',2,2),']<br />'; 
echo '[',getWords2($string,'works',1,3),']<br />'; 

但是，如果单词出现多次，您希望发生什么？或者如果这个词没有出现在字符串中？

编辑

getWords2的扩展版本，返回到关键字的出现集数

$string = 'PHP is a widely-used general-purpose scripting language that is especially suited for Web development. The current version of PHP is 5.3.3, released on July 22, 2010. The online manual for PHP is an excellent resource for the language syntax and has an extensive list of the built-in and extension functions. Most extensions can be found in PECL. PEAR contains a plethora of community supplied classes. PHP is often paired with the MySQL relational database.'; 

echo $string,'<br />'; 

function getWords3($string,$word,$before=0,$after=0,$maxFoundCount=1) { 
    $stringWords = str_word_count($string,1); 
    $stringWordsPos = array_keys(str_word_count($string,2)); 

    $foundCount = 0; 
    $foundInstances = array(); 
    while ($foundCount < $maxFoundCount) { 
     if (($myWordPos = array_search($word,$stringWords)) === false) 
      break; 
     ++$foundCount; 
     if (($myWordPos+$after) >= count($stringWords)) 
      $after = count($stringWords) - $myWordPos - 1; 
     $startPos = $stringWordsPos[$myWordPos-$before]; 
     $endPos = $stringWordsPos[$myWordPos+$after] + strlen($stringWords[$myWordPos+$after]); 

     $stringWords = array_slice($stringWords,$myWordPos+1); 
     $stringWordsPos = array_slice($stringWordsPos,$myWordPos+1); 

     $foundInstances[] = substr($string,$startPos,$endPos-$startPos); 
    } 
    return $foundInstances; 
} 

var_dump(getWords3($string,'PHP',2,2,3));