Include value from associative array into multidimensional associative array

Question

I'd like to build on $arr1 with the special row from $arr2.

$arr1 = Array
(
    [0] => Array
        (
            [1111] => Array
                (
                    [itemid] => 4321
                    [itemcode] => item1
                    [avail] => 0
                )
            [2222] => Array
                (
                    [itemid] => 4321
                    [itemcode] => item2
                    [avail] => 20
                )
         )
    [1] => Array
        (
            [3333] => Array
                (
                    [itemid] => 1342
                    [itemcode] => item3
                    [avail] => 10
                )
         )
)

$arr2 = Array
(
    [1111] => Array
        (
            [itemid] => 4321
            [itemcode] => item1
            [special] => 10
        )

    [2222] => Array
        (
            [itemid] => 4321
            [itemcode] => item2
            [special] => 2
        )

    [3333] => Array
        (
            [itemid] => 1342
            [itemcode] => item3
            [special] => 1
        )
)

My desired result is like so:

$arr1 = Array
(
    [0] => Array
        (
            [1111] => Array
                (
                    [itemid] => 4321
                    [itemcode] => item1
                    [avail] => 0
                    [special] => 10
                )
            [2222] => Array
                (
                    [itemid] => 4321
                    [itemcode] => item2
                    [avail] => 20
                    [special] => 2
                )
         )
    [1] => Array
        (
            [3333] => Array
                (
                    [itemid] => 1342
                    [itemcode] => item3
                    [avail] => 10
                    [special] => 1
                )
         )
)

I understand how to do this with two mutlidimensional arrays but the additional array wrapping around $arr1 has me thinking I need to for loop but I don't want to make a 3rd new array, just take on the special value to $arr1.

I've tried variations of the following:

$arr1 = array_map(function($v) use($arr2){
     $v = (array)$v;
     $key = array_search(array_column($v["itemcode"]), array_column($arr2, 'itemcode'));
     $v["special"] = $arr2[$key]["special"];
     return $v;
}, $arr1);

Which fails to append the data to the special index even though the new index appears in $arr1(new).

Guidance is much appreciated! Maps are so cool and powerful but I cannot seem to grasp their awesomeness in its entirety.

@Barmar a mistake, it's supposed to be $arr2. I've corrected it — mezzomix
– mezzomix, Commented Sep 14, 2018 at 20:28

Barmar · Accepted Answer · 2018-09-14 20:29:37Z

3

Just use nested foreach loops. Use reference variables so you can modify the original array in place.

foreach ($arr1 as &$el1) {
    foreach ($el1 as $key => &$el2) {
        $el2['special'] = $arr2[$key]['special'];
    }
}

answered Sep 14, 2018 at 20:29

Barmar

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1 Comment

mezzomix Over a year ago

It's so simple! Thank you so much, I keep defaulting to the harder more complex functions!

steven · Accepted Answer · 2018-09-14 20:37:28Z

1

Another way to modify $arr1 without a reference:

    foreach($arr1 as $k => $v){
        foreach($v as $idx => $elem) {
            if(array_key_exists($idx, $arr2)) {
                $arr1[$k][$idx]['special'] = $arr2[$idx]['special'];
            }
        }
    }

answered Sep 14, 2018 at 20:37

steven

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