Remove all array elements except those with index in another array

Question

I'm looking for a PHP function that I think I have used before. I have two arrays: one main array of values, and one array of indexes. I want an easy way to keep all values whose index are in second the array, and remove the rest. So, I have already solved the problem by going through the array with a foreach loop like this:

$array      = array("Foo", "Bar", "Foobar", "Test");
$indexlist  = array(0, 2);

foreach($array as $index => $value) {

    if(in_array($index, $indexlist)) {

        $result[]   = $value;

    }

}

So my question is not how to solve the problem itself, but rather: is there a PHP function that does this? The question is based really only on curiosity because I think I remember that I used such a function earlier. The loop above results in the following output, which the requested function also should:

Array
(
    [0] => Foo
    [1] => Foobar
)

array_intersect_key() + Just array_flip() the indexlist array (Your output just is a bit weird.) — Rizier123
– Rizier123, Commented Aug 12, 2015 at 17:20
Yeah the output was just a misstake. Thank you, array_intersect_key() is the function i was looking for! Please write an answer and I will mark it as correct :) — Emil
– Emil, Commented Aug 12, 2015 at 18:53

Rizier123 · Accepted Answer · 2015-08-12 19:02:10Z

1

You probably look for array_intersect_key(). Also since in your second array the keys are the values, you just have to flip the array with array_flip().

And the you can put it together, e.g.

print_r(array_intersect_key($array, array_flip($indexlist)));

answered Aug 12, 2015 at 19:02

Rizier123

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Comments

aditya7822 · Accepted Answer · 2015-08-12 17:31:03Z

0

$array      = array("Foo", "Bar", "Foobar", "Test");
$indexlist  = array(0, 2);

foreach($indexlist as $value) {

    if(isset($array[$value])) {

        $result[]   = $array[$value];

    }

}

answered Aug 12, 2015 at 17:31

aditya7822

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1 Comment

Henrique Barcelos Over a year ago

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