[Resolved] how could I sort this list of integers?

[Beaker]

Hi, I know enough about PHP to get a script to run, but now I have a project which needs a way to sort a list of integers so they are in the order of a master list.

for example:
$masterlist=array('4','6','3','5','7','1');

and my variable array would have a subset, like maybe
$incoming=array('1','7','5','6');

I need to sort $incoming so that its in the order of $masterlist, so when I print $incoming, I see
6
5
7
1

both of my arrays are integers, so at least I don't have to worry about strings, and my master list is like 4000 integers large.

any suggestions or help would be greatly appreciated

[drawmack]

I would probably use a third array called positions like so:

$masterlist=array('4','6','3','5','7','1'); 
$incoming=array('1','7','5','6'); 
$positions = array();

//here is the magic.
foreach($incoming as $id) {
    //set $i = the index of masterlist that contains the
    //current value of incoming.
    $i=0;
    while($masterlist[$i] != $id) {$i++;}
    $positions[$id] = $i;
}

//sort positions which will maintain the key to value pointer
//and put the array in the order of the values.
arsort($positions);

//set incoming to be the keys from positions
$incoming = array_keys($positions);

//now incoming is sorted in the order of masterlist.
foreach($incoming as $current) {
  echo $current . "<br />\n";
}

[Beaker]

oh, that's brilliant! thank you

I changed your arsort to asort, but same thing

thanks again!!!

[drawmack]

no problem please mark the thread resolved

[Beaker]

oh, I didn't know about marking

/me looks for how

found it! in the FAQ sticky thread

thanks again!!!