Question

I have some Problems reducing a multidimensional array into a normal one.

I have an input array like this:

Array
(
[0] => Array (
        [0] => 17
        [1] => 99
    )
[1] => Array (
        [0] => 17
        [1] => 121
    )
[2] => Array (
        [0] => 99
        [1] => 77
    )
[3] => Array (
        [0] => 45
        [1] => 51
    )
[4] => Array (
        [0] => 45
        [1] => 131
    )

So I have a multidimensional array with some overlaps in the values (eg 17,99 and 17,121)
Now I want to have an output like this:

Array
(
[0] => Array (
        [0] => 17
        [1] => 99
        [2] => 121
        [3] => 77
    )
[2] => Array (
        [0] => 45
        [1] => 51
        [3] => 131
    )

I want to save, which articles are the same in my database this way. The output array shpuld still be a multidimesional array, but every number on the second level should be unique in the array.

I’m trying to solve this for more than a week now, but I dont get it to work. I know it should be easy…but anyway – I dont get it 😀

This is what i got so far:

$parity_sorted = array();
    foreach($arr as $key => $a){
        if(count($parity_sorted) > 0){
        foreach($parity_sorted as $key2 => $arr_new){
            if(in_array($a[0], $arr_new) || in_array($a[1], $arr_new)){
                if(!in_array($a[0], $arr_new)){array_push($parity_sorted[$key2], $a[0]);}
                if(!in_array($a[1], $arr_new)){array_push($parity_sorted[$key2], $a[1]);}
            } else {
                array_push($parity_sorted, array($a[0],$a[1]));
            }
        }
        } else {
            array_push($parity_sorted, array($a[0],$a[1]));
        }

    }

Did you maybe already solve problem like this or is there a much easier way? Maybe I just think too complicated (It’s not my first try, but this code was the last try)

Any help would be appreciated. Thanks a lot

Answer 1

Here is my revised code given your comment and a DEMO of it working as expected. ( http://codepad.org/CiukXctS )

<?php

$tmp = array();
foreach($array as $value)
{
    // just for claraty, let's set the variables
    $val1 = $value[0];
    $val2 = $value[1];
    $found = false;
    foreach($tmp as &$v)
    {
        // check all existing tmp for one that matches
        if(in_array($val1, $v) OR in_array($val2, $v))
        {
            // this one found a match, add and stop
            $v[] = $val1;
            $v[] = $val2;
            // set the flag
            $found = true;
            break;
        }
    }
    unset($v);

    // check if this set was found  
    if( ! $found)
    {
        // this variable is new, set both
        $tmp[] = array(
                $val1,
                $val2,
                );
    }
}

// go trough it all again to ensure uniqueness
$array = array();
foreach($tmp as $value)
{
    $array[] = array_unique($value); // this will eliminate the duplicates from $val2
}

ORIGIN ANSWER

The question is badly asked, but I’ll attempt to answer what I believe the question is.

You want to gather all the pairs of arrays that have the same first value in the pair correct?

$tmp = array();
for($array as $value)
{
    // just for claraty, let's set the variables
    $val1 = $value[0];
    $val2 = $value[1];

    if(isset($tmp[$val1])) // we already found it
    {
        $tmp[$val1][] = $val2; // only set the second one
    }
    else
    {
        // this variable is new, set both
        $tmp[$val1] = array(
            $val1,
            $val2,
        );
    }
}
// go trough it all again to change the index to being 0-1-2-3-4....
$array = array();
foreach($tmp as $value)
{
    $array[] = array_unique($value); // this will eliminate the duplicates from $val2
}