Question

i have a (dynamic) array, which in this example contains 4 sets of data (5 fields per set), but it could be only one set or up to 25 sets.

Array ( [lightwattage1] => 50 [lightvoltage1] => 12 [lightquantity1] => 2 [lightusage1] => 4 [lightcomment1] => [lightwattage2] => 60 [lightvoltage2] => 24 [lightquantity2] => 4 [lightusage2] => 5 [lightcomment2] => [lightwattage3] => 30 [lightvoltage3] => 240 [lightquantity3] => 4 [lightusage3] => 2 [lightcomment3] => [lightwattage4] => 25 [lightvoltage4] => 12 [lightquantity4] => 2 [lightusage4] => 6 [lightcomment4] => ) 

which i’d like to turn into something like

Array ( Array ( [lightwattage1] => 50 [lightvoltage1] => 12 [lightquantity1] => 2 [lightusage1] => 4 [lightcomment1] => ),
        Array ( [lightwattage2] => 60 [lightvoltage2] => 24 [lightquantity2] => 4 [lightusage2] => 5 [lightcomment2] => ),
        Array ( [lightwattage3] => 30 [lightvoltage3] => 240 [lightquantity3] => 4 [lightusage3] => 2 [lightcomment3] => ), 
        Array ( [lightwattage4] => 25 [lightvoltage4] => 12 [lightquantity4] => 2 [lightusage4] => 6 [lightcomment4] => )
        )

the original array is created this way:

$light = Array();

foreach( $_POST as $key => $val )
{
//field names that start with light to go in this array
    if (strpos($key, 'light') === 0) {
        $light[$key] = $val;
    }
}

the field name digit is already added with JS before form submission, and not by php script.
any hint much appreciated.

Answer 1

Try this:

$prefixes = array();
$postfixes = array();
foreach($original_array as $key=>$value)
{
        preg_match('/^([^\d]*)(\d+)$/',$key,$matches);
        if(count($matches)>1)
        {
                if(!in_array($matches[1], $prefixes)) $prefixes[] = $matches[1];
                if(!in_array($matches[2], $postfixes)) $postfixes[] = $matches[2];
        }
}   
$new_array = array();
foreach($postfixes as $postfix)
{
        $new_element = array();
        foreach($prefixes as $prefix)
        {
                if(isset($original_array[$prefix.$postfix])) $new_element[$prefix.$postfix] = $original_array[$prefix.$postfix];
        }
        $new_array[] = $new_element; 
}

given an $original_array equal to described, will produce $new_array:

Array
(
    [0] => Array
        (
            [lightwattage1] => 50
            [lightvoltage1] => 12
            [lightquantity1] => 2
            [lightusage1] => 4
            [lightcomment1] => 
        )

    [1] => Array
        (
            [lightwattage2] => 60
            [lightvoltage2] => 24
            [lightquantity2] => 4
            [lightusage2] => 5
            [lightcomment2] => 
        )

    [2] => Array
        (
            [lightwattage3] => 30
            [lightvoltage3] => 240
            [lightquantity3] => 4
            [lightusage3] => 2
            [lightcomment3] => 
        )

    [3] => Array
        (
            [lightwattage4] => 25
            [lightvoltage4] => 12
            [lightquantity4] => 2
            [lightusage4] => 6
            [lightcomment4] => 
        )

)

I was uncertain about how much you knew about the elements or their order, so this code basically takes any collection of elements that end in numbers and rearranges them in groups that have the same ending number.