Consolidate multidimensional array data by deep array value and ensure default-keyed subarrays within each group

Question

I have an array that I'd like to restructure. I want to group items by turn. I can figure out how to extract data from the array using foreach($arr['history'] as $obj) my issue is with populating a new array using a loop.

Currently it looks like this:

Array ( 
[history] => Array ( 
    [id] => 23452435 
    [legend] => Array ( 

        [0] => Array ( 
            [player] => me 
            [turn] => 1 
            [card] => Array ( 
                [name] => foo 
            ) 
        ) 

        [1] => Array ( 
            [player] => me 
            [turn] => 1 
            [card] => Array ( 
                [name] => bar
            ) 
        ) 

        [2] => Array ( 
            [player] => opponent 
            [turn] => 1
            [card] => Array (
                [name] => derp 
            ) 
        ) 

        [3] => Array ( 
            [player] => opponent 
            [turn] => 2 
            [card] => Array ( 
                [name] => hoo
            ) 
        ) 
    ) 
))

I want it to look like the following, but I can't figure out how to automatically create and populate this structure. This is an array with a sub-array for each turn, containing an array for me and opponent

Array (
[0] => Array (
    [me] => Array (
        [0] => foo
        [1] => bar
    )
    [opponent] = Array (
        [0] => derp
    )

)
[1] => Array (
    [me] => Array ()
    [opponent] => Array (
        [0] => hoo
    )
))

mickmackusa · Accepted Answer · 2024-09-09 04:10:25Z

1

Try this script which subtracts 1 from the turn value to declare the first level key and then the player value as the second level key, then pushes the card value as a new subarray element.

$result = [];
foreach ($data['history']['legend'] as $list) {
    $result[$list['turn'] - 1][$list['player']][] = $list['card']['name'];
}

Fiddle it! http://ideone.com/BtKOKJ

edited Sep 9, 2024 at 4:10

mickmackusa♦

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answered Jun 6, 2016 at 22:46

Naveed Ahmed

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1 Comment

Simon Over a year ago

This is what I needed. With a few adjustments I made it work for my dataset. Thanks :) Also for some reason I had to separate the foreach loop into two, one for each key.

michaJlS · Accepted Answer · 2016-06-06 22:24:54Z

1

You can just start adding data to the new array. PHP is extremely forgiving.

$historyByTurns = array();
foreach ($arr['history'] as $historyItem) {
    foreach ($historyItem['legend'] as $legendItem) {
        $turn = $legendItem['turn'];
        $player = $legendItem['player'];
        if (!array_key_exists($turn, $historyByTurns)) {
            $historyByTurns[$turn] = array();
        }
        if (!array_key_exists($player, $historyByTurns[$turn])) {
            $historyByTurns[$turn][$player] = array();
        }
        foreach ($legendItem as $card) {
            $historyByTurns[$turn][$player][] = $card['name'];
        }
    }
}

You will have to test it, as I have no way to do that ATM.

answered Jun 6, 2016 at 22:24

michaJlS

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2 Comments

Simon Over a year ago

This answer provided the same result as the other answer, but both weren't 100% what I needed, but helped me understand my issue. A few adjustments made this work though. Thanks :)

mickmackusa Over a year ago

It is not necessary to instantiate an empty parent array when pushing data into it with square brace syntax.

mickmackusa · Accepted Answer · 2024-09-09 04:06:02Z

I'm demonstrate a solution implementing array destructuring syntax in a foreach() for convenience value access. Inside the loop body, a reference variable will be maintained to ensure that every unique turn contains a me and an opponent subarray. Pushing data into references avoids subtracting from the turn value to dictate keys (subtraction might produce non-indexed keys depending on turn values).

Code: (Demo)

$result = [];
foreach ($data['history']['legend'] as ['player' => $p, 'turn' => $t, 'card' => ['name' => $cn]]) {
    if (!isset($ref[$t])) {
        $ref[$t] = ['me' => [], 'opponent' => []];
        $result[] =& $ref[$t];
    }
    $ref[$t][$p][] = $cn;
}
var_export($result);

@Naveed's answer does not ensure that each group has a me and an opponent subarray.

@michaJlS's answer doesn't actually work at all when fed the asker's data.

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