Keyword Extractor

A simple little PHP function to automatically extract keywords for addition into your content.

Posted by Paul Whitrow, 16th June, 2008 | Permalink | 2 Comments

Here is a useful little PHP function for anyone that wishes to use it.

It's a keyword extractor that searches a body of text and extracts words that occur according to a set amount of times that you specify, compares them to an array of common words to ignore and then returns a comma separated list of the words found as a string for inclusion into your page.

I use it in the top om my content pages to generate extra keywords.

Not a big deal, but can be quite useful.

// common words to ignore in meta keyword extract. 
// extend as required
$stopwords = array(
"about",
"above",
"across",
"after",
"afterwards"
);
function keyword_extract($text, $minStrLen = 2, $minOccur = 1)
{
    global $stopwords;
    $text = strip_tags($text);
    $text = str_replace("\n","", $text);
    $text = str_replace("\r","", $text);
    $text = str_replace(",","", $text);
    $text = str_replace(".","", $text);
    $text = str_replace(";","", $text);
    $text = strtolower($text);
    $punc =". , : ; ' ? ! ( ) \" \\";
    $punc = explode(" ",$punc);
    foreach($punc as $value){
        $text = str_replace($value, " ", $text);
    }
    $words = explode(" ", $text);
	$keywords = array();
    foreach ($words as $value) {
        $common = false;
        if (strlen($value) > $minStrLen){
            foreach($stopwords as $commonWord){
                if ($commonWord == $value){
                    $common = true;
                }
                else{
                }
            }
            if($common != true){
                $keywords[] = $value;
            }
            else{
            }
        }
        else{
        }
    }    $keywords = array_count_values($keywords);
    arsort($keywords);
    $str = "";
    foreach ($keywords as $key => $value) {
        if ($value > $minOccur){
			$str .= $key.", ";
        }
    }
   $str = trim($str, ", ");
   return $str;
}

Call it into your keywords like this:

keyword_extract($CONTENT [string], 2 [int], 1 [int]);

and presto, instant keyword list.

Posted on Monday 16th June, 2008 at 11:09 am by Paul Whitrow, and filed under PHP and SEO