Question

When a duplicate is found in URL I want to:

1. Take ‘score’ and add it to the original
2. Take ‘engine’ string and append it to the original
3. Then delete the entire duplicate entry

array
  0 => 
    array
      'url' => string 'http://blahhotel.com/'
      'score' => int 1
      'engine' => string 'cheese'
  1 => 
    array
      'url' => string 'http://www.blahdvd.com/'
      'score' => int 2
      'engine' => string 'cheese'
  2 => 
    array
      'url' => string 'http://blahhotel.com/'
      'score' => int 1
      'engine' => string 'pie'
  3 => 
    array
      'url' => string 'http://dictionary.reference.com/browse/blah'
      'score' => int 2
      'engine' => string 'pie'
  4 => 
    array
      'url' => string 'http://dictionary.reference.com/browse/blah'
      'score' => int 1
      'engine' => string 'apples'

It should look like this in the end:

array
  0 => 
    array
      'url' => string 'http://blahhotel.com/'
      'score' => int 2
      'engine' => string 'cheese, pie'
  1 => 
    array
      'url' => string 'http://www.blahdvd.com/'
      'score' => int 2
      'engine' => string 'cheese'
  3 => 
    array
      'url' => string 'http://dictionary.reference.com/browse/blah'
      'score' => int 3
      'engine' => string 'pie, apples'

Answer 1

I believe this meets your requirements.

Based on the desired output you provided, it appeared that you wanted to preserve the numeric indices of each entry. If you don’t actually need to preserve those numbers, you can remove the second foreach loop and the lines regarding the $indices variable, then just return $tmpList.

function reduceEntries($entries)
{
    $tmpList = array();
    $indices = array();

    foreach ($entries as $i => $entry) {
        if (isset($tmpList[$entry['url']])) {
            $tmpList[$entry['url']]['score'] += $entry['score'];
            $tmpList[$entry['url']]['engine'] .= ', ' . $entry['engine'];
        } else {
            $tmpList[$entry['url']] = $entry;
            $indices[$entry['url']] = $i;
        }
    }

    // rebuild final array with indices
    $finalList = array();
    foreach ($tmpList as $url => $entry) {
        $finalList[$indices[$url]] = $entry;
    }

    return $finalList;
}

(Here’s a working example on codepad.)