Sorting array by count of subarray

Question

I have an array looking like this:

Array(
   ['some_first_category'] => Array(
            ['some_first_name'] => Array(
                           [0]=>'[email protected]',
                           [1]=>'[email protected]',
                           [2]=>'[email protected]',
                           [3]=>'[email protected]' )
             ['some_second_name'] => Array (
                           [1]=>'[email protected]',
                           [2]=>'[email protected]')
             ['some_third_name'] => Array(
                           [1]=>'[email protected]',
                           [2]=>'[email protected]',
                           [3]=>'[email protected]',
                           [4]=>'[email protected]' )
   ['some_second_category'] => Array(
            ['some_first_name'] => Array(
                           [0]=>'[email protected]' )
             ['some_second_name'] => Array(
                           [1]=>'[email protected]',
                           [2]=>'[email protected]',
                           [3]=>'[email protected]',
                           [4]=>'[email protected]')
             ['some_third_name'] => Array(
                           [1]=>'[email protected]',
                           [2]=>'[email protected]'))

And I want to sort the array by the number of values of that has the names, In my case I want to become this array:

Array(
   ['some_first_category'] => Array(
             ['some_third_name'] => Array(
                           [1]=>'[email protected]',
                           [2]=>'[email protected]',
                           [3]=>'[email protected]',
                           [4]=>'[email protected]' )
            ['some_first_name'] => Array(
                           [0]=>'[email protected]',
                           [1]=>'[email protected]',
                           [2]=>'[email protected]',
                           [3]=>'[email protected]' )
             ['some_second_name'] => Array (
                           [1]=>'[email protected]',
                           [2]=>'[email protected]')

   ['some_second_category'] => Array(
             ['some_second_name'] => Array(
                           [1]=>'[email protected]',
                           [2]=>'[email protected]',
                           [3]=>'[email protected]',
                           [4]=>'[email protected]')
             ['some_third_name'] => Array(
                           [1]=>'[email protected]',
                           [2]=>'[email protected]')
            ['some_first_name'] => Array(
                           [0]=>'[email protected]' ))

This means sorting categories by name by the number(count) of values of the names. Someone can help me? Thanks in advance,

Aäron

I see that you want to sort the second level ("name") by number of child elements descending, but do you also want to sort the first level ("category") by some logic? — Passerby
– Passerby, Commented Feb 5, 2013 at 10:01
It isn't sorted. It's just a display specific to your needs. — hjpotter92
– hjpotter92, Commented Feb 5, 2013 at 10:02
I want also some one to wash my car! but if I washed and I failed, its ok to ask a friend to help me! — user1646111
– user1646111, Commented Feb 5, 2013 at 10:03
ppl should learn that this side is supposed to give support, not full solutions to questions. You and only you have to do the work, if you need help that's ok, but asking for the solution w/o trying anything it's just cheap. — Naryl
– Naryl, Commented Feb 5, 2013 at 10:06

Baba · Accepted Answer · 2013-02-05 10:13:01Z

17

All you need is uasort

uasort($list, function ($a, $b) {
    $a = count($a);
    $b = count($b);
    return ($a == $b) ? 0 : (($a < $b) ? -1 : 1);
});

Full Example

$list = Array(
   'some_first_category' => Array(
            'some_first_name' => Array(
                           0=>'[email protected]',
                           1=>'[email protected]',
                           2=>'[email protected]',
                           3=>'[email protected]' ),
             'some_second_name' => Array (
                           1=>'[email protected]',
                           2=>'[email protected]'),
             'some_third_name' => Array(
                           1=>'[email protected]',
                           2=>'[email protected]',
                           3=>'[email protected]',
                           4=>'[email protected]' )
        ),
   'some_second_category' => Array(
            'some_first_name' => Array(
                           0=>'[email protected]' ),
             'some_second_name' => Array(
                           1=>'[email protected]',
                           2=>'[email protected]',
                           3=>'[email protected]',
                           4=>'[email protected]'),
             'some_third_name' => Array(
                           1=>'[email protected]',
                           2=>'[email protected]'))

    );

$list = array_map(function ($v) {
    uasort($v, function ($a, $b) {
        $a = count($a);
        $b = count($b);
        return ($a == $b) ? 0 : (($a < $b) ? 1 : - 1);
    });
    return $v;
}, $list);


print_r($list);

Output

Array
(
    [some_first_category] => Array
        (
            [some_first_name] => Array
                (
                    [0] => [email protected]
                    [1] => [email protected]
                    [2] => [email protected]
                    [3] => [email protected]
                )

            [some_third_name] => Array
                (
                    [1] => [email protected]
                    [2] => [email protected]
                    [3] => [email protected]
                    [4] => [email protected]
                )

            [some_second_name] => Array
                (
                    [1] => [email protected]
                    [2] => [email protected]
                )

        )

    [some_second_category] => Array
        (
            [some_second_name] => Array
                (
                    [1] => [email protected]
                    [2] => [email protected]
                    [3] => [email protected]
                    [4] => [email protected]
                )

            [some_third_name] => Array
                (
                    [1] => [email protected]
                    [2] => [email protected]
                )

            [some_first_name] => Array
                (
                    [0] => [email protected]
                )

        )

)

edited Feb 5, 2013 at 10:13

answered Feb 5, 2013 at 10:05

Baba

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4 Comments

dognose Over a year ago

dont put functions in parameters of functions. this is not jQuery :P

DaveRandom Over a year ago

@dognose So you'd rather pointlessly assign the closure to a variable or clutter the global namespace with a function identifier then? The only reason to avoid inline closures is if you need to support <=5.2, if you need to do that you need a better job and/or host.

Ari Takeshi Over a year ago

Thanks a lot Baba !! The usort function I already tried it myself but it doesn't maintain the key of the array's. Thanks for the help everybody!

dognose Over a year ago

@DaveRandom A Sort function is not related to the context imho. So I might reuse it, so yes, I would put it somewhere global because then I don't need to rewrite or copy/paste it.

manish1706 · Accepted Answer · 2016-08-31 12:48:54Z

5

Using uksort:

uksort($yourArray, function($a, $b) { return count($b) - count($a); });

Using array_multisort:

array_multisort(array_map('count', $yourArray), SORT_DESC, $yourArray);

and you can see uasort as well

best of luck :)

answered Aug 31, 2016 at 12:48

manish1706

1,60925 silver badges22 bronze badges

2 Comments

Abhishek Goel Over a year ago

Perfect thanks... array_multisort(array_map('count', $yourArray), SORT_DESC, $yourArray); this worked for me

murtho Over a year ago

uasort($yourArray, function($a, $b) { return count($b) - count($a); }); worked great for me. if you want to reverse the sort order you can swap $a and $b in the count functions.

Community · Accepted Answer · 2017-05-23 12:24:53Z

1

You should use usort function. Refer here.

function sort_sub($a,$b)
{
$res= count($b)-count($a);
return $res;
}

usort($array_name,'sort_sub')

edited May 23, 2017 at 12:24

CommunityBot

11 silver badge

answered Feb 5, 2013 at 10:05

Vishnu R

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