Merge two associative arrays by same key

Question

I have two associative array having one value in common, like

ARRAY 1(
  [0]=>
  array(2) {
    ["ID"]=> "AAAA"
    ["Name"]=> "Apple"
  }
  [1]=>
  array(2) {
    ["ID"]=> "BBBB"
    ["Name"]=> "Avocado"
  }
  [3]=>
  array(2) {
    ["ID"]=> "CCCC"
    ["Name"]=> "Banana"
  }
)



Array2 (
  [0]=>
  array(4) {
    ["ID"]=> "AAAA"
    ["Taste"]=> "Yumi"
    ["Location"]=> "France"
    ["Price"]=> "Cheap"
  }
  [1]=>
  array(4) {
    ["ID"]=> "CCCC"
    ["Taste"]=> "Yumi"
    ["Location"]=> "Africa"
    ["Price"]=> "Cheap"
  }
  [3]=>
  array(4) {
    ["ID"]=> "BBBB"
    ["Taste"]=> "Yumi"
    ["Location"]=> "America"
    ["Price"]=> "Expansive"
  }
  [3]=>
  array(4) {
    ["ID"]=> "HZGA"
    ["Taste"]=> "Berk"
    ["Location"]=> "Moon"
    ["Price"]=> "Expansive"
  }    

)

I would like to merge them both by their ID. A simple merge isn't possible because they arn't sorted, have 40.000 + values and don't have the same size.

I planned to use a double foreach, and create a third array were the ID was common, I dropped the idea. Since having to parse 40.000 values in the first array for each of the 40.000 values from the second array take too long.

Is there some solution ? I would like to having it look like this at final :

ArrayFinal (
  [0]=>
  array(4) {
    ["ID"]=> "AAAA"
    ["Name"]=> "Apple"
    ["Taste"]=> "Yumi"
    ["Location"]=> "France"
    ["Price"]=> "Cheap"
  }
  [1]=>
  array(4) {
    ["ID"]=> "CCCC"
    ["Name"]=> "Banana"
    ["Taste"]=> "Yumi"
    ["Location"]=> "Africa"
    ["Price"]=> "Cheap"
  }
  [3]=>
  array(4) {
    ["ID"]=> "BBBB"
    ["Name"]=> "Avocado"
    ["Taste"]=> "Yumi"
    ["Location"]=> "America"
    ["Price"]=> "Expansive"
  }
)

Answer 1

You cannot avoid to loop. But foreach is pretty fast. Tested on an array of 50.000 and it took 0.04 seconds.

What this wil do is:

• create a TMP array
• get the KEY and ID values from ARRAY1
• put them as 'ID'=>key in the TMP array
• loop ARRAY2, get the ID
• look up the corresponding ID in TMP
• get the key from ARRAY1
• merge ARRAY1 and ARRAY2

You'll end up with ARRAY1 having the data from ARRAY2

$ar1=[...]; //original array 1
$ar2=[...]; //original array 2

// get ID=> key pairs
$kv=[];
foreach($ar1 as $k => $v){
    $kv[ $v['id'] ] = $k;
    }

// loop ARRAY2
foreach($ar2 as $k => $v){
    if( array_key_exists( $v['id'] , $kv ) ){
        $ar1[ $kv[$v['id']] ] = array_merge( $ar1[$kv[$v['id']]] , $ar2[$k] );
        }
    }

Answer 2

https://eval.in/1011901

 <?php 

$a = [['ID'=> 'TOTO'], ['ID' => 'TATA']];
$b = [['ID' => 'TATA', 'RA' => 'T'], ['ID' => 'TOTO', 'COUCOU' => 2]];

$final = [];

foreach($a as $c){
  if(!isset($final[$c['ID']])){
    $final[$c['ID']] = $c;
  }else{
    $final[$c['ID']] += $c;
  }
}
foreach($b as $c){
  if(!isset($final[$c['ID']])){
    $final[$c['ID']] = $c;
  }else{
    $final[$c['ID']] += $c;
  }
}
var_dump(array_values($final));

OUTPUT

array(2) {
  [0]=>
  array(2) {
    ["ID"]=>
    string(4) "TOTO"
    ["COUCOU"]=>
    int(2)
  }
  [1]=>
  array(2) {
    ["ID"]=>
    string(4) "TATA"
    ["RA"]=>
    string(1) "T"
  }
}