PHP number processing

Question

In a multidimensional array, each array has a field 'order'. I need to change this value as follows:

0 -> 3    
1 -> 2    
2 -> 1    
3 -> 0
4 -> 7
5 -> 6
6 -> 5
7 -> 4
8 -> 9
9 -> 8

etc...

Ill be doing this while iterating through the array as follows

$c = 0;
        foreach($data['images'] as $i)
        {
            //$i['order'] contains the original order value

            $processed_imgs[$c]['file'] = $i['file'];
            $processed_imgs[$c]['text'] = $i['text'];
            $processed_imgs[$c]['order'] = 'X';                     
            $c++;
        }

$i['order'] contains the original order value (left column in the first code snippet, coming out of the DB ASC) and should be changed to the corresponding number in the right column.

So basically, the value needs to be changed to the reverse order, while looking at each set of numbers in blocks of 4. I will not know what the highest order number will be, it will increase as new images are added.

What's the best way to do this using the above foreach?

this seems to answer your questions quite well stackoverflow.com/questions/1316916/… — Prix
– Prix, Commented Aug 2, 2010 at 19:17

Peter Bailey · Accepted Answer · 2010-08-02 19:26:45Z

1

Just re-map it

$orderMap = array( 3, 2, 1, 0, 7, 6, 5, 4, 9, 8 );

$c = 0;
foreach($data['images'] as $i)
{
    //$i['order'] contains the original order value

    $processed_imgs[$c]['file'] = $i['file'];
    $processed_imgs[$c]['text'] = $i['text'];
    $processed_imgs[$c]['order'] = $orderMap[$i['order']];                     
    $c++;
}

answered Aug 2, 2010 at 19:26

Peter Bailey

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maschka · Accepted Answer · 2010-08-02 19:52:24Z

0

$processed_imgs[$c]['order'] = floor($i['order']/4)*4 + 3-$i['order'] % 4;

and then some correction for the last block...

if (count($data['images'])-1-$i['order'] < count($data['images'])%4) {
    $processed_imgs[$c]['order'] -= 4-count($data['images'])%4;
}

Of course re-mapping with an additional array works fine, but you still need to generate the map somehow.

edited Aug 2, 2010 at 19:52

answered Aug 2, 2010 at 19:14

maschka

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3 Comments

stef Over a year ago

That gives: 0->3 1->2 2->1 3->0 4->4 5->3 6->2 7->1 8->5 9->4

maschka Over a year ago

Sorry, this edited version gives the result from your textual description. It doesn't match your example for 8 and 9 though. Not sure which way you wanted it.

stef Over a year ago

That works but only if there is a total number of images that is a multiple of 4. Close ...

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