How to generate excerpt with most searched words in PHP?

Question

Here is an excerpt function:

    function excerpt($text, $phrase, $radius = 100, $ending = \"...\") {
270             if (empty($text) or empty($phrase)) {
2         


        

Answer 1

I came up with the below to generate excerpts. You can see the code here https://github.com/boyter/php-excerpt It works by finding all the locations of the matching words, then takes an excerpt based on which words are the closest. In theory this does not sound very good but in practice it works very well.

Its actually very close to how Sphider (for the record it lives in searchfuncs.php from line 529 to 566) generates its snippets. I think the below is much easier to read and is without bugs which exist in Sphider. It also does not use regular expressions which makes it a bit faster then other methods I have used.

I blogged about it here http://www.boyter.org/2013/04/building-a-search-result-extract-generator-in-php/

 2) {
        // skip the first as we check 1 behind
        for($i=1; $i < $loccount; $i++) { 
            if($i == $loccount-1) { // at the end
                $diff = $locations[$i] - $locations[$i-1];
            }
            else {
                $diff = $locations[$i+1] - $locations[$i];
            }

            if($smallestdiff > $diff) {
                $smallestdiff = $diff;
                $startpos = $locations[$i];
            }
        }
    }

    $startpos = $startpos > $prevcount ? $startpos - $prevcount : 0;
    return $startpos;
}

// 1/6 ratio on prevcount tends to work pretty well and puts the terms
// in the middle of the extract
function extractRelevant($words, $fulltext, $rellength=300, $prevcount=50, $indicator='...') {

    $textlength = strlen($fulltext);
    if($textlength <= $rellength) {
        return $fulltext;
    }

    $locations = _extractLocations($words, $fulltext);
    $startpos  = _determineSnipLocation($locations,$prevcount);

    // if we are going to snip too much...
    if($textlength-$startpos < $rellength) {
        $startpos = $startpos - ($textlength-$startpos)/2;
    }

    $reltext = substr($fulltext, $startpos, $rellength);

    // check to ensure we dont snip the last word if thats the match
    if( $startpos + $rellength < $textlength) {
        $reltext = substr($reltext, 0, strrpos($reltext, " ")).$indicator; // remove last word
    }

    // If we trimmed from the front add ...
    if($startpos != 0) {
        $reltext = $indicator.substr($reltext, strpos($reltext, " ") + 1); // remove first word
    }

    return $reltext;
}
?>