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

Answer 1

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.