Sort then split a PHP array? - php

Question

Here is a var_dump of my array:
array(6) {
[0]=> string(4) "quack"
["DOG"]=> string(4) "quack"
[1]=> string(4) "quack"
["CAT"]=> string(4) "quack"
[2]=> string(4) "Aaaaarrrrrggggghhhhh"
["CAERBANNOG"]=> string(4) "Aaaaarrrrrggggghhhhh"
}
(just for fun I've included two puns in this code, try and find them!)
How do I split this array into two arrays, one containing all the quacks; the other Aaaaarrrrrggggghhhhh?
Note that it won't always be in consecutive order, so was thinking maybe nested hashmaps, something like:
Check if (isset($myarr['$found_val']))
Append that array if found
Else create that place with a new array
But not sure how the arrays are implemented, so could be O(n) to append, in which case I'd need some other solution...

Answer 1

You can just group them based on values and store the keys
$array = array(0 => "quack","DOG" => "quack",1 => "quack","CAT" => "quack",2 => "Aaaaarrrrrggggghhhhh","CAERBANNOG" => "Aaaaarrrrrggggghhhhh");
$final = array();
foreach ( $array as $key => $value ) {
if (! array_key_exists($value, $final)) {
$final[$value] = array();
}
$final[$value][] = $key;
}
var_dump($final);
Output
array
'quack' =>
array
0 => int 0
1 => string 'DOG' (length=3)
2 => int 1
3 => string 'CAT' (length=3)
'Aaaaarrrrrggggghhhhh' =>
array
0 => int 2
1 => string 'CAERBANNOG' (length=10)

Answer 2

Try this
$quacks_arr = array_intersect($your_array, array('quack'));
$argh_arr = array_intersect($your_array, array('Aaaaarrrrrggggghhhhh'));
If you want to sort them, then just do ksort
ksort($quacks_arr);
ksort($argh_arr);

Answer 3

Just in case anyone wants to do this in a more of and odd way:
Updated with air4x's idea of using only a single item array, instead of array_fill(0,count($a),$v). Makes it's much more sensible.
$a = array(
0 => "quack",
"DOG" => "quack",
1 => "quack",
"CAT" => "quack",
2 => "Aaaaarrrrrggggghhhhh",
"CAERBANNOG" => "Aaaaarrrrrggggghhhhh"
);
$b = array();
foreach( array_unique(array_values($a)) as $v ) {
$b[$v] = array_intersect($a, array($v));
}
echo '<xmp>';
print_r($b);
Totally not optimal - difficult to read - but still interesting :)