Array grouping in PHP

Question

I have an array in PHP:

array (size=xxx)
  0 => 
    array (size=9)
      'cat' => string 'FIRST CAT'
      'dur' => string '10'
      'type' => string 'Type description 10'
      'start' => string '00:00'
      'end' => string '01:00'
      'desc' => string 'Event description 10-1'
      'price' => string 'xxx'
      'extra' => string 'yyy'
  1 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string ''
      'start' => string '01:00'
      'end' => string '02:00'
      'desc' => string 'Event description 10-2'
      'price' => string ''
      'extra' => string ''
  2 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string ''
      'start' => string '02:00'
      'end' => string '03:00'
      'desc' => string 'Event description 10-3'
      'price' => string ''
      'extra' => string ''
  3 => 
    array (size=9)
      'cat' => string ''
      'dur' => string '20'
      'type' => string 'Type description 20'
      'start' => string '00:00'
      'end' => string '01:00'
      'desc' => string 'Event description 20-1'
      'price' => string 'xxx'
      'extra' => string 'yyy'
  4 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string ''
      'start' => string '01:00'
      'end' => string '02:00'
      'desc' => string 'Event description 20-2'
      'price' => string ''
      'extra' => string ''
  5 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string 'Type description 21'
      'start' => string '00:00'
      'end' => string '01:00'
      'desc' => string 'Event description 21-1'
      'price' => string 'xxx'
      'extra' => string 'yyy'
  6 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string ''
      'start' => string '01:00'
      'end' => string '02:00'
      'desc' => string 'Event description 21-2'
      'price' => string ''
      'extra' => string ''
  7 => 
    array (size=9)
      'cat' => string 'SECOND CAT'
      'dur' => string '10'
      'type' => string 'Type description 100'
      'start' => string '00:00'
      'end' => string '01:00'
      'desc' => string 'Event description 100-1'
      'price' => string 'xxx'
      'extra' => string 'yyy'
  8 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string ''
      'start' => string '01:00'
      'end' => string '02:00'
      'desc' => string 'Event description 100-2'
      'price' => string ''
      'extra' => string ''
  9 => 
    array (size=9)
      'cat' => string ''
      'dur' => string '20'
      'type' => string 'Type description 200'
      'start' => string '00:00'
      'end' => string '01:00'
      'desc' => string 'Event description 200-1'
      'price' => string 'xxx'
      'extra' => string 'yyy'
  10 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string ''
      'start' => string '01:00'
      'end' => string '02:00'
      'desc' => string 'Event description 200-2'
      'price' => string ''
      'extra' => string ''
  11 => 
    array (size=9)
      'cat' => string ''
      'dur' => string ''
      'type' => string 'Type description 210'
      'start' => string '00:00'
      'end' => string '01:00'
      'desc' => string 'Event description 210-1'
      'price' => string 'xxx'
      'extra' => string 'yyy'
  etc...

I need to group this array first by cat, then by dur, then type. This type array would have two strings - price and extra and another array which would consist of all the events data - start, end and desc. Final array outline (based on example above) should look like this:

'FIRST CAT'                                           // 'cat'
    '10'                                              // 'dur'
      'Type description 10', 'xxx', 'yyy'             // 'type', 'price', 'extra'
          (array of events)
          '00:00', '01:00', 'Event description 10-1'  // 'start', 'end', 'desc'
          '01:00', '02:00', 'Event description 10-2'  // 'start', 'end', 'desc'
          '02:00', '03:00', 'Event description 10-3'  // 'start', 'end', 'desc'
    '20'
      'Type description 20', 'xxx', 'yyy'
          (array of events)
          '00:00', '01:00', 'Event description 20-1'
          '01:00', '02:00', 'Event description 20-2'
      'Type description 21', 'xxx', 'yyy'
          (array of events)
          '00:00', '01:00', 'Event description 21-1'
          '01:00', '02:00', 'Event description 21-2'
'SECOND CAT'
    '10'
      'Type description 100', 'xxx', 'yyy'
          (array of events)
          '00:00', '01:00', 'Event description 100-1'
          '01:00', '02:00', 'Event description 100-2'
    '20'
      'Type description 200', 'xxx', 'yyy'
          (array of events)
          '00:00', '01:00', 'Event description 200-1'
          '01:00', '02:00', 'Event description 200-2'
      'Type description 210', 'xxx', 'yyy'
          (array of events)
          '00:00', '01:00', 'Event description 210-1'
          '01:00', '02:00', 'Event description 210-2'

What would be the simplest way to convert my existing array to the one I need in the end?

@nl-x - http://meta.stackexchange.com/questions/122986/is-it-ok-to-leave-what-have-you-tried-comments — Expedito, Jun 06 '13 at 12:34
@nl-x I tried to follow the logic behind this post http://stackoverflow.com/questions/12706359/php-array-group but I'm a bit confused because my original array have empty values... — errata, Jun 06 '13 at 12:52

Expedito · Accepted Answer · 2013-06-06T14:08:48.683

The following does what you're looking for:

$out = array();
foreach ($arr as $key => $value){
    $cat = $value['cat'];
    $dur = $value['dur'];
    $type = $value['type'];
    $out[$cat][$dur][$type][] = $value['start'].', '.$value['end'].', '.$value['desc'];
}
print_r($out);

EDIT:

I modified my code because of a request to use the last category when the category is empty. So, here's my modified code:

    $out = array();
    $last_cat = '';
    foreach ($arr as $key => $value){
        $cat = $value['cat'];
        $dur = $value['dur'];
        $type = $value['type'];
        if (empty($cat)){
            $cat = $last_cat;
        } else {
            $last_cat = $cat;
        }
        $out[$cat][$dur][$type][] = $value['start'].', '.$value['end'].', '.$value['desc'];
    }
    print_r($out);

The ouput of this code is as follows:

[FIRST CAT] => Array(
        [10] => Array(
            [Type description 10] => Array(
                [0] => 00:00, 01:00, Event description 10-1
            )
        )
        [] => Array(
            [] => Array(
                    [0] => 01:00, 02:00, Event description 10-2
                    [1] => 02:00, 03:00, Event description 10-3
                    [2] => 01:00, 02:00, Event description 20-2
                    [3] => 01:00, 02:00, Event description 21-2
                )

            [Type description 21] => Array(
                    [0] => 00:00, 01:00, Event description 21-1
                )
        )
        [20] => Array(
            [Type description 20] => Array(
                    [0] => 00:00, 01:00, Event description 20-1
                )
        )
    )
[SECOND CAT] => Array(
        [10] => Array(
            [Type description 100] => Array(
                    [0] => 00:00, 01:00, Event description 100-1
                )
            )
        [] => Array(
            [] => Array(
                    [0] => 01:00, 02:00, Event description 100-2
                    [1] => 01:00, 02:00, Event description 200-2
                )
            [Type description 210] => Array(
                    [0] => 00:00, 01:00, Event description 210-1
                )
            )
        [20] => Array(
            [Type description 200] => Array(
                    [0] => 00:00, 01:00, Event description 200-1
                )
            )
    )

This is very helpful, but my `$out` has additional "blank category" array (`'FIRST CAT'`, `''` and `'SECOND CAT`) which is not the desired output. I see now how should I construct my output and will give it a try :) — errata, Jun 06 '13 at 12:50
Do you want to eliminate all data that has a blank catecory? Your original array had a lot of data with no category. — Expedito, Jun 06 '13 at 12:53
No, I don't want to eliminate that, I'd like to group it under the belonging category. — errata, Jun 06 '13 at 12:54
That's what I did. There is a group in the array that has no category name. The key in the output appears as empty brackets: []. Maybe I'm not understanding "belonging category." If the data has no category, to what catagory does it belong? — Expedito, Jun 06 '13 at 13:01
Ah yes, the original array is a bit 'dumb' :) The data belongs to specific category until the array don't have another `cat` defined. In my example, array elements from 0-6 belong to `'FIRST CAT'` and elements from 7-11 belong to `'SECOND CAT'`. — errata, Jun 06 '13 at 13:07

score 0 · Answer 2 · answered Jun 06 '13 at 12:00

0

I think it would be best to use the http://php.net/manual/en/function.ksort.php ksort function.

answered Jun 06 '13 at 12:00

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Array grouping in PHP

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