PHP merge similar values in an array

Question

$arr = (a => array(1,2,3), b => array(1,2,3), c => array(4,5), d=> array(8,9,10), e => array(8,9), f => array(9,10);

I would like to merge similar values, so that I would get:

Problem #1 (similar values, harder):

$new_arr = (a_b => array(1,2,3), c => (4,5), d_e_f => array(8,9,10));

Problem #2 (exactly same values, easier):

$new_arr = (a_b => array(1,2,3), c => (4,5), d => array(8,9,10), e => array(8,9), f => array(9,10));

What's the most effective way to to the above?? May be a hard question to solve :D

Thanks!

A possible first step for #2 (a version of array_unique that works with arrays, but doesn't create a_b key names) is in the User Contributed Notes to array_unique: php.net/manual/en/function.array-unique.php#97285 — Pekka
– Pekka, Commented Aug 14, 2010 at 10:20

LatinSuD · Accepted Answer · 2010-08-14 10:21:09Z

1

I'd call this finding the "connected components" of a graph.

http://en.wikipedia.org/wiki/Connected_component_%28graph_theory%29

answered Aug 14, 2010 at 10:21

LatinSuD

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bcosca · Accepted Answer · 2010-08-14 11:01:45Z

0

$unique=array_unique($arr,SORT_REGULAR);
foreach (array_diff_key($arr,$unique) as $key=>$value) {
    $oldkey=array_search($value,$unique);
    unset($unique[$oldkey]);
    $unique[$oldkey.'_'.$key]=$value;
}
var_dump($unique);

answered Aug 14, 2010 at 11:01

bcosca

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