php turning array into multi-dimensional array

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.

Walk the original array and when you see that a key has already been set, you'll know that it's time to start to put the data in a new sub-array. — Aurelio De Rosa
– Aurelio De Rosa, Commented Oct 18, 2011 at 0:55

Petah · Accepted Answer · 2011-10-18 01:10:13Z

2

This is not an exacty answer to you question, but...

You can use arrays in POST variables like so:

<input name="light[1][wattage]" />
<input name="light[1][voltage]" />
<input name="light[2][wattage]" />
<input name="light[2][voltage]" />

will give you:

$_POST['light'] == array(
    1 => array(
        'wattage' => '...',
        'voltage' => '...',
    ),
    2 => array(
        'wattage' => '...',
        'voltage' => '...',
    ),
)

answered Oct 18, 2011 at 1:10

Petah

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1 Comment

rotezecke Over a year ago

i like this approach but i would have to rewrite my form, its jQUery and JS validation. i'll use this next time. cheers

ghbarratt · Accepted Answer · 2012-07-28 16:03:50Z

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.

edited Jul 28, 2012 at 16:03

answered Oct 18, 2011 at 1:20

ghbarratt

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2 Comments

rotezecke Over a year ago

Oops, this works well if there's only one digit, but as soon as it goes over 9 (lightwattage10 etc) the script fails.

rotezecke Over a year ago

changing the preg_match line did the trick: preg_match('/^(.*)(\d+)$/',$key,$matches); to preg_match('/^([^0-9]*)(\d+)$/',$key,$matches);

poplitea · Accepted Answer · 2011-10-18 01:08:55Z

0

Try this:

$outarr = array()
$subarr = array()
$i=0;
foreach($_POST as $key => $val)
{
    //only include keys starting with light:
    if (strpos("light", $key)==0)
    {
        //create a new subarray each time we find a key that starts with "lightwattage":
        if ($i>0 && strpos("lightwattage", $key)==0)
        {
            $outarr[] = $subarr;
        }
        $subarr[$key] = $val;
        $i++;
    }
}
$outarr[] = $subarr;

//$outarr contains what you want here

answered Oct 18, 2011 at 1:08

poplitea

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