PHP How to calculate duplicate values in array

Question

I would like to calculate duplicate values in my array by "groupid":

Example:

Array
(
    [0] => Array
        (
            [id] => 1230
            [groupid] => 177
            [activity_group_last] => 1229
            [name] => First name
        )

    [1] => Array
        (
            [id] => 1231
            [groupid] => 177
            [activity_group_last] => 1229
            [name] => Second name
        )

    [2] => Array
        (
            [id] => 1232
            [groupid] => 178
            [activity_group_last] => 1229
            [name] => Other name
        )

)

Output array (2 groupid = 177 and 1 groupid = 178):

Array
(
    [0] => Array
        (
            [id] => 1231
            [groupid] => 177
            [activity_group_last] => 1229
            [name] => Second name
            [count] => 2

        )

    [1] => Array
        (
            [id] => 1232
            [groupid] => 178
            [activity_group_last] => 1229
            [name] => Other name
            [count] => 1
        )
)

Thanks!

Um..calculate? what kind of calculation, and on what fields? Please be more specific — Nick Rolando
– Nick Rolando, Commented Aug 11, 2011 at 7:10
There seems to be some data-loss in your example: Only 1 id value and 1 name value is kept when the 2 arrays with identical groupids are grouped. Is that on purpose? — Flambino
– Flambino, Commented Aug 11, 2011 at 7:14
It's right example. Just calculate groupids count and remove duplicate. — XTRUST.ORG
– XTRUST.ORG, Commented Aug 11, 2011 at 7:22
If it happens that your array is populated by a SQL query, please do this from the query, not with some PHP code. — Vincent Savard
– Vincent Savard, Commented Aug 11, 2011 at 8:05
This is my query: $sql = 'SELECT wall.id, members.groupid, last.activity_group_last, groups.name FROM #__community_wall AS wall, #__community_groups_members AS members, #__mod_table AS last, #__community_groups AS groups WHERE members.memberid ='.intval($uid).' AND members.approved = 1 AND members.groupid = wall.contentid AND wall.post_by !='.intval($uid).' AND wall.type="groups" AND wall.id > last.activity_group_last AND last.userid ='.intval($uid).' AND last.activity_group_last > 0 AND last.activity_group_last_new = "0" AND groups.id = members.groupid ORDER BY wall.id'; — XTRUST.ORG
– XTRUST.ORG, Commented Aug 11, 2011 at 8:42

realmfoo · Accepted Answer · 2011-08-11 08:04:09Z

1

If $value contains your array, then:

$count = array_count_values(array_map(function($item) {
    return $item['groupid'];
}, $value));
var_dump($count);

$_tmp = $count;
$unique = array_filter($value, function(&$item) use (&$_tmp, $count) {
    if (!--$_tmp[$item['groupid']]) {
        $item['count'] = $count[$item['groupid']];
        return true;
    }
    return false;
});
var_dump($unique);

results in:

array(2) {
  [1]=>
  array(5) {
    ["id"]=>
    int(1231)
    ["groupid"]=>
    int(177)
    ["activity_group_last"]=>
    int(1229)
    ["name"]=>
    string(11) "Second name"
    ["count"]=>
    int(2)
  }
  [2]=>
  array(5) {
    ["id"]=>
    int(1232)
    ["groupid"]=>
    int(178)
    ["activity_group_last"]=>
    int(1229)
    ["name"]=>
    string(10) "Other name"
    ["count"]=>
    int(1)
  }
}

edited Aug 11, 2011 at 8:04

answered Aug 11, 2011 at 7:23

realmfoo

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3 Comments

nikc.org Over a year ago

+1, but you could add some comments, unless you aspire for the "Most Obscure Code Snippet of the Day" -award ;-)

XTRUST.ORG Over a year ago

But I need to add: [count] => X to output array

XTRUST.ORG Over a year ago

Yes my friend, you are the rock!

Lucas Meyer · Accepted Answer · 2011-08-12 14:35:01Z

0

You can also do this using an iterative function. If your input array is stored in $input and you want the results in $output:

function remove_duplicates($input_array) {
  $output_array = array();            // Create an empty array for output
  foreach($input_array as $input) {   // Loop the input array
    if(array_key_exists($input['groupid'], $output_array)) {
      // We've already seen this groupid at least once
      // Increment count
      $input['count'] = $output_array[$input['groupid']]['count'] + 1;
    } else {
      // First time we've seen this groupid
      // Set count to 1
      $input['count'] = 1;
    }
    // Store data in $output_array, indexed by group_id
    $output_array[$input['groupid']] = $input;
  }
}

// This is your input array
$input = array(array('id'=>1230,'groupid'=>177,'activity_group_last'=>1229,'name'=>'First name'),
           array('id'=>1231,'groupid'=>177,'activity_group_last'=>1229,'name'=>'Second name'),
           array('id'=>1232,'groupid'=>178,'activity_group_last'=>1229,'name'=>'Other name'));
// This will set the output array correctly
$output = remove_duplicates($input);

edited Aug 12, 2011 at 14:35

answered Aug 11, 2011 at 7:26

Lucas Meyer

6793 silver badges7 bronze badges

3 Comments

XTRUST.ORG Over a year ago

The is a problem with this function. It output: Array ( [] => Array ( [id] => 1279 [groupid] => 177 [activity_group_last] => 1275 [name] => Name [count] => 4 ) ) But we have other array (input): [2] => Array ( [id] => 1232 [groupid] => 178 [activity_group_last] => 1229 [name] => Other name )

XTRUST.ORG Over a year ago

The is a problem with this function. It output: Array ( [] => Array ( [id] => 1279 [groupid] => 177 [activity_group_last] => 1275 [name] => Name [count] => 4 ) )

Lucas Meyer Over a year ago

Script is updated to set $input to the values you originally provided; in a quick test, it works fine. Can you be more specific with the problem you're seeing?

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