更有效地减去数组

Question

I have a few questions. Got this array:

$array_1  = array(
    "1" => "4",
    "2" => "8",
    "3" => "12",
    "4" => "16",
    "5" => "20",
    "6" => "24",
    "7" => "28",
    "8" => "32",
    "9" => "36",
    "10" => "40",
    "11" => "44",
    "12" => "48",
    "13" => "52",
    "14" => "56",
    "15" => "60",
    "16" => "64",
    "17" => "68",
    "18" => "72",
    "19" => "76",
    "20" => "80",
    "21" => "84",
    "22" => "88",
    "23" => "92",
    "24" => "96",
    "25" => "100",
    "26" => "104",
    "27" => "108",
    "28" => "112",
    "29" => "116",
    "20" => "120",
    "31" => "124",
    "32" => "128",
    "33" => "132",
    "34" => "136",
    "35" => "140",
    "36" => "144",
    "37" => "148",
    "38" => "152",
    "39" => "156",
    "40" => "160",
    "41" => "164",
    "42" => "168",
    "43" => "172",
    "44" => "176",
    "45" => "180",
    "46" => "184",
    "47" => "188",
    "48" => "192",
    "49" => "196",
    "50" => "200"
);

I would like to subtract $array_1 by 1,2,3,4 into multiple arrays. So far I have done it by having other arrays:

$array_2  = array(
    "1" => "1",
    "2" => "1",
    ...
    "49" => "1",
    "50" => "1"
);

$array_3  = array(
    "1" => "2",
    "2" => "2",
    ...
    "49" => "2",
    "50" => "2"
);
// All the way to values of 4

Then with this I would do an array_diff to get the lowered value.

I was wondering firstly is there a better way (more efficient) to have the array subtract rather than repeat the 1,2,3,4 50 times each.

Secondly, is there a more efficient way to have $array_1 have the values of multiple of 4 up to 200?

Thirdly, do I need an array to subtract from $array_1 to lower the value? Is there a better way to this like: $array_1 - 1

INTENDED OUTPUT

// $array_1 - $array_2 (value of 1)
$minus_one = array(
    "1" => "3",
    "2" => "7",
    "3" => "11",
    ...
);
// $array_1 - $array_3 (value of 2)
$minus_two = array(
    "1" => "2",
    "2" => "6",
    "3" => "10",
    ...
);
// $array_1 - $array_4 (value of 3)
$minus_one = array(
    "1" => "1",
    "2" => "4",
    "3" => "8",
    ...
);

Answer 1

While xdazz is solution is right. You also direct can generate final intended array by

$array_1 = array_fill(1, 50, null);
array_walk($array_1, function(&$item, $key){
  $item = $key * 4;
});

$minus_one = $minus_two = $minus_three = array();
foreach($array_1 as $key => $value)
{
    $minus_one[$key] = $value - 1 ;
    $minus_two[$key] = $value - 2 ;
    $minus_three[$key] = $value - 3 ;
}