Combine 2 arrays of different length

Question

I have an array with 100 values(array1). I have another array with 8 values(array2). I want to take the values from array2 and use them as keys and extract the values in array1 for those keys.

The array_combine function won't work as they are of different lengths.

I have tried

function array_combine2($arr1, $arr2) {
    $count = min(count($arr1), count($arr2));
    return array_combine(array_slice($arr1, 0, $count), array_slice($arr2, 0, $count));
}

But this doesn't work.....this gives me an array with the correct keys, but the values are incorrect, I think because it is slicing array1.

Could someone give some assistance. There is a fair amount of literature on this already, I know, but they all give solutions very similar to the one above which isn't working.

Many thanks for the time you have taken.

Answer 1

something like this one:

function combine($array1, $array2) {
    $array3 = array();
    foreach ($array2 as $key => $value) { //loop through all entries of array2

        //get the entry of array1 that corresponds to the value of array2's entry
        if (isset($array1[$value]) {
            $array3[$key] = $array1[$value] 
        }
    }

    return $array3;
}

I haven't tested it but it should give you something for thought.

Answer 2

Try this. loop the 2nd array and extract the value from array1 with using value of array2 as index for array1

foreach ( $array2 as $arr2 ){
   $temp[]= $array[ $arr2 ];
}
return $temp;

Answer 3

you can use below code

function array_combine2($arr1, $arr2) {
    foreach($arr2 as $val){
     $arr3[] = $arr1[$val];
     }

    return $arr3;
}

For inctanse,

    $arr1['x'] = 2;
$arr1['y'] = 3;
$arr1['z'] = 4;

$arr2[0] = 'x';
$arr2[1] = 'y';
$arr2[2] = 'z';

the above function will return the below as resbonse

$arr3[0] = 2;
$arr3[1] = 3;
$arr3[2] = 4;

Answer 4

Unfortunately, array_slice() will disregard any association between the arrays based on keys/indexes. array_slice() operates using offset values; this is why it is the wrong tool for the job.

array_intersect_key() is a suitable call to filter an array using another array's keys.

Code: ( Demo )

for($char='A',$score=100; $score>0; ++$char,--$score){
    $dr_img_scores1["IMG_$char"]=$score;    // generate 100 unique elements
}
//var_export($dr_img_scores1);  // uncomment to see what this looks like

// eight arbitrary elements to use as extraction keys on $array1
$dr_img_scores2=['IMG_CL'=>13,'IMG_Z'=>44,'IMG_BP'=>82,'IMG_L'=>50,
                 'IMG_CD'=>2,'IMG_X'=>91,'IMG_BM'=>7,'IMG_AV'=>0];    

var_export(array_intersect_key($dr_img_scores1,$dr_img_scores2));
// notice that $dr_img_scores1's element order is preserved

Output:

array (
  'IMG_L' => 89,
  'IMG_X' => 77,
  'IMG_Z' => 75,
  'IMG_AV' => 53,
  'IMG_BM' => 36,
  'IMG_BP' => 33,
  'IMG_CD' => 19,
  'IMG_CL' => 11,
)

Note: If $dr_img_scores1 or $dr_img_scores2 are not in order, you can use ksort() on them to synchronize their orders to permit an easy visual comparison of scores.