sorting php array in case it exsit in other array

Question

$a= [ '1' => ['key'=>'1','id'=>'4' ],
      '2' => ['key'=>'2','id'=>'1' ],
      '3' => ['key'=>'3','id'=>'5' ]
    ]

$b = [1,5]

so i want to sort array $a so that if $a[*]['id'] is in $b array it should be first.

so in this example the out put should be

$a = ['2' => ['key'=>'2','id'=>'1' ],
      '3' => ['key'=>'3','id'=>'5' ]
      '1' => ['key'=>'1','id'=>'4' ],
    ]

i tried

uasort($a, function($k, $v) use ($b) {
        return in_array($v['id'],$b) ? 1 : -1;
    });

yet failed :(

is there an optimum method for doing such a trick using any of the php sorting functions?

yp, yet didnt know how to dive to reach 'id' value to compare it in the call back function — Momen Zalabany
– Momen Zalabany, Commented Jan 11, 2014 at 19:55

evalarezo · Accepted Answer · 2014-01-11 20:34:39Z

3

uasort($a, function ($x, $y) use ($b) {
    return !in_array($x['id'], $b);
});

You must note that $y is not used and the code will work without referencing it, but I prefer this way for completeness.

X and Y are any two array values. If the sort function returns 1, X is placed last (first Y, last X). If returns -1, X go first (first X, last Y).

In this case, the sort function will return true (equivalent to 1) if $x[id] is not in $b, so the order will be first Y, then X. This sort will move to the last positions all the array values whith id not in $b.

After say that, you can also use this code without $y:

uasort($a, function ($x) use ($b) {
    return !in_array($x['id'], $b);
});

edited Jan 11, 2014 at 20:34

answered Jan 11, 2014 at 19:56

evalarezo

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2 Comments

Momen Zalabany Over a year ago

can you please explain to me what are the variables that uasort pass to the function ? i mean what is $y ?

Abhik Chakraborty Over a year ago

@Edakos I answered but I feel you have the efficient one so one up from my end :)

Abhik Chakraborty · Accepted Answer · 2014-01-11 20:07:37Z

0

Here is another implementation

$a= array( '1' => array('key'=>'1','id'=>'4' ), '2' => array('key'=>'2','id'=>'1' ), '3' => array('key'=>'3','id'=>'5' ) );
$b = array(1,5);
asort($a); 
function customuksort($t1, $t2) {
    global $a;

    return $a[$t1] < $a[$t2] ? -1 : 1;
}
uksort($b, 'customuksort');

print_r($a);

The output is

Array ( [1] => Array ( [key] => 1 [id] => 4 ) [2] => Array ( [key] => 2 [id] => 1 ) [3] => Array ( [key] => 3 [id] => 5 ) )

edited Jan 11, 2014 at 20:07

answered Jan 11, 2014 at 20:00

Abhik Chakraborty

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1 Comment

Abhik Chakraborty Over a year ago

Follow the answer from @Edakos he has better solution.

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