"Join" Arrays with values from left array to keys from right array

Question

I have to arrays that i want to join together without iterating them.
Backgroundinfo:

$Arr1 is an array of all Groups that a User is in.
$Arr2 is an array of all Contentpages associated to the Groups as the array key.

My aim is to get an array with all contentpages that the user is allowed to see

$Arr1 = array("Group1","Group3","Group5");

$Arr2["Group1"] = array("Content1","Content2");
$Arr2["Group2"] = array("Content5");
$Arr2["Group3"] = array("Content3");

My Result should be an array with all "Content" Elements:

array("Content1","Content2","Content3");

Is there some trick with array_fill_keys or array_merge to avoid iterating?

gen_Eric · Accepted Answer · 2015-09-09 13:09:33Z

3

You can try array_flip and array_intersect_key.

$intersect = array_intersect_key($Arr2, array_flip($Arr1))

Then you can flatten that into one array using array_merge.

$content = call_user_func_array('array_merge', $intersect);

DEMO: https://eval.in/430592

answered Sep 9, 2015 at 13:09

gen_Eric

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2 Comments

Jason McCreary Over a year ago

+ I always preach PHP has an array function for every need. This is great proof of that.

Arjuna Wenzel Over a year ago

Awesome thank you! Does somebody know how this will be on performance side - in comparision with a foreach loop?

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