Group elements by value

Question

I have an array like that:

array(
    [0] => array(
        'date' => '2017-12-20',
        'name' => 'test A',
        'kwa' => 'kwa1, kwa2'
    ),
    [1] => array(
        'date' => '2017-12-20',
        'name' => 'test B',
        'kwa' => ''
    ),
    [2] => array(
        'date' => '2017-12-21',
        'name' => 'test C',
        'kwa' => 'kwa1'
    ),
    [3] => array(
        'date' => '2017-12-22',
        'name' => 'test D',
        'kwa' => ''
    ),
    [4] => array(
        'date' => '2017-12-22',
        'name' => 'test E',
        'kwa' => ''
    ),
)

I want group all elements has the same day into a array. Something like that:

array(
    ['2017-12-20'] => array( '0', '1'),
    ['2017-12-21'] => array( '2' ),
    ['2017-12-22'] => array( '3', '4' ),
)

PHP has any function to do this? Or anyone know the best solution? Thank you!!!

an easy solution is to iterate over your main array, and as you encounter dates build a new array and insert into the correct place. Hope this helps! — N. Ivanov, Dec 21 '17 at 09:55
Possible duplicate of [PHP create array group by key](https://stackoverflow.com/questions/45965029/php-create-array-group-by-key) — Roy Bogado, Dec 21 '17 at 09:56
@N.Ivanov I already think about your idea, but still find other maybe better than? :D — Mít, Dec 21 '17 at 09:56

score 2 · Accepted Answer · answered Dec 21 '17 at 09:58

Here is your solution...

Input

<?php 
    $array = array(
        array(
            'date' => '2017-12-20',
            'name' => 'test A',
            'kwa' => 'kwa1, kwa2'
        ),array(
            'date' => '2017-12-20',
            'name' => 'test B',
            'kwa' => ''
        ),array(
            'date' => '2017-12-21',
            'name' => 'test C',
            'kwa' => 'kwa1'
        ),array(
            'date' => '2017-12-22',
            'name' => 'test D',
            'kwa' => ''
        ),array(
            'date' => '2017-12-22',
            'name' => 'test E',
            'kwa' => ''
        ),
    );

Solution

    $new = array();
    foreach($array as $r){
       $new[$r['date']][] = array('name'=>$r['name'],'kwa' => $r['kwa']); 
    }
    echo "<pre>";print_r($new);

?>

Output

    Array
(
    [2017-12-20] => Array
        (
            [0] => Array
                (
                    [name] => test A
                    [kwa] => kwa1, kwa2
                )

            [1] => Array
                (
                    [name] => test B
                    [kwa] => 
                )

        )

    [2017-12-21] => Array
        (
            [0] => Array
                (
                    [name] => test C
                    [kwa] => kwa1
                )

        )

    [2017-12-22] => Array
        (
            [0] => Array
                (
                    [name] => test D
                    [kwa] => 
                )

            [1] => Array
                (
                    [name] => test E
                    [kwa] => 
                )

        )

)

score 2 · Answer 2 · answered Dec 21 '17 at 09:58

2

$arr = array();

foreach($array1 as $key => $item)
{
   $arr[$item['date']][$key] = $key;
}

echo "<pre>";
print_r($arr);

answered Dec 21 '17 at 09:58

TarangP

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score 1 · Answer 3 · answered Dec 21 '17 at 10:06

I would use something like the following:

$array = [
    [
        'date' => '2017-12-20',
        'name' => 'test A',
        'kwa' => 'kwa1, kwa2'
    ],
    [
        'date' => '2017-12-20',
        'name' => 'test B',
        'kwa' => ''
    ],
    [
        'date' => '2017-12-21',
        'name' => 'test C',
        'kwa' => 'kwa1'
    ],
    [
        'date' => '2017-12-22',
        'name' => 'test D',
        'kwa' => ''
    ],
    [
        'date' => '2017-12-22',
        'name' => 'test E',
        'kwa' => ''
   ],
];

$formatted = [];
foreach ($array as $k => $v) {
    $formatted[$v['date']] = $formatted[$v['date']] ?? [];
    array_push($formatted[$v['date']], $k);
}

print_r($formatted);

Group elements by value

3 Answers3