Prendi il numero x di parole prima e dopo una determinata parola chiave?

Question

Come posso ottenere il [x] numero di parole prima e dopo una determinata parola chiave in una stringa in PHP? Sto cercando di rendere noti i risultati di una query mysql adattata alla parola chiave come uno snippet.

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 />'; 

Ma cosa vuoi che accada se la parola appare più volte? O se la parola non appare nella stringa?

EDIT

Versione estesa di getWords2 per tornare fino a un determinato numero di occorrenze della parola chiave

$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));