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I' ve fallen into endless foreach's.

I got an array:

$array[0] = array( A,B );
$array[1] = array( A,C );
$array[2] = array( B,C );
$array[3] = array( B,E );
$array[4] = array( C,E );

What I need to get is this:

$array[0] = array( A,B,C );
$array[1] = array( A,B,E );
$array[2] = array( A,C,E );
$array[3] = array( B,C,E );

Is there an easy way to accomplish this by a simple function? Also I need to create 4 value arrays of this results above: A,B,C,E etc.

share|improve this question
You skipped "D". – landons Apr 6 '12 at 22:37
Could you explain a little bit more precise, what you mean? 1. The alphabet we know looks more like 'ABCD' and then for your first part AB,AC,BC,BE,CE look a bit strange to me, like you have forgotten AE... – Kerwindena Apr 6 '12 at 22:41
It don't think it matter what the letters are. He just wants the cartesian product of the unique array elements. – webbiedave Apr 6 '12 at 22:45
Looks like you missed A,E pair in the first part. Otherwise I see no logic in the way you organize them. @webbiedave No, it is not a cartesian product. It is a permutation list. – kirilloid Apr 6 '12 at 22:46
it is not alphabet in there, treat letters as numbers A=1,B=2 and so on. I need to create patterns from first example ( 3 item ones ) and from 3 item arrays I need to create 4 item arrays.. and so on – Trouble Apr 6 '12 at 22:47
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3 Answers

up vote 0 down vote accepted

Something like this (not tested):

$out = array();
foreach($array as $first) {
    foreach($array as $second) {
        if (array_slice($first, 1) == array_slice($second, -1)) {
            $copy = $first;
            $last = array_slice($second, -1, 1);
            $copy []= $last[0];
            $out []= $copy;
        }
    }
}
share|improve this answer
Thank you for this, but as Kerwindena code, this would only for for creating 3 item long arrays. I already have messy code for making 2 item long arrays. Thats why I am trying to make function for that. – Trouble Apr 6 '12 at 23:10
No, this is a general code for 2->3, 3->4, etc generation. For any step. – kirilloid Apr 6 '12 at 23:12
Oh.. sorry than I didn't get it. I will try it now. – Trouble Apr 6 '12 at 23:13
This is almost perfect.. changed == statement on != and it gives good results but some of them are the same like A,B,C and A,C,B ( it is the same for this case ).So now I have to sort it and replace duplicated arrays. Thank you for your effort! – Trouble Apr 6 '12 at 23:27
if you sort the input, and every input is only once present, each output will be sorted an also only once present... – Kerwindena Apr 6 '12 at 23:30
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up vote 1 down vote

If you need to generate array of unique permutations, you can use code from this article:

http://www.dannyherran.com/2011/06/finding-unique-array-combinations-with-php-permutations/

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Thank you for this link but what I need to make is not strictly permutations, it is joining similar arrays into wider one. – Trouble Apr 6 '12 at 22:52
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up vote 0 down vote

What about:

$array[0] = array( A,B );
$array[1] = array( A,C );
$array[2] = array( B,C );
$array[3] = array( B,E );
$array[4] = array( C,E );

$array2 = new array();

for($i = 0; $i < count($array); $i++)
{
    for($j = 0; $j < count($array); $j++)
    {
        if($array[$i][1] == $array[$j][0])
        {
            $array2[] = new array($array[$i][0], $array[$i][1], $array[$j][1]);
        }
    }
}
share|improve this answer
thanks, this would work but only for making 3 item long arrays, but than I need to match 2 first items to create 4 ones. That would require like 2 more if statements - too complicated if there were 5 item ones possible. – Trouble Apr 6 '12 at 23:07
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