Get a subset of an array based on an array of keys

array_diff_key and array_intersect_key are probably what you want.

I always want this too. Like a PHP version of Underscore's pick.

It's ugly and counter-intuitive, but what I sometimes do is this (I think this may be what prodigitalson was getting at):

$a = ['foo'=>'bar', 'zam'=>'baz', 'zoo'=>'doo'];

// Extract foo and zoo but not zam
print_r(array_intersect_key($a, array_flip(['foo', 'zoo'])));
/*
Array
(
    [foo] => bar
    [zoo] => doo
)
*/

array_intersect_key returns all the elements of the first argument whose keys are present in the 2nd argument (and all subsequent arguments, if any). But, since it compares keys to keys, I use array_flip for convenience. I could also have just used ['foo' => null, 'zoo' => null] but that's even uglier.