Sort results not as expected

[beakerboy]

A little background. In the actual array I'm working with, the a, b, c's are primary keys. One shouldn't expect them to actually be in order. This example uses a, b, c to verify if a sort worked properly.

I want to sort the array so the result will have a,b,c,d,e,f,g,h, etc in order.

Notice that if you examine the $test array, looking from top to bottom, all generation 2 rows are in order. Same with 3, 4 and 5. The only problem with the current order is each generation is seperated by other "in order" groups of generations. If rows with a specific generation never switch positions, the result should be obtained. The fact that the input is a,b,c,d and the result is a, e d, b means that rows with like generation ARE in fact switching position. How can I prevent this? This isn't the way it's supposed to work, is it? My ultimate question is...why is this not working as I'd expect and do you have a suggestion on how to maintain the original order of each generation?

Here is my demo code:

<?php

function generationsort($a, $b) {
        $agen=$a["Generation"];
        $bgen=$b["Generation"];
        return $agen - $bgen;
}

$test=array();
$test[a]["Generation"]=1;
$test[b]["Generation"]=2;
$test[c]["Generation"]=2;
$test[d]["Generation"]=2;
$test[e]["Generation"]=2;
$test[f]["Generation"]=3;
$test[g]["Generation"]=3;
$test[l]["Generation"]=4;
$test[m]["Generation"]=4;
$test[h]["Generation"]=3;
$test[i]["Generation"]=3;
$test[j]["Generation"]=3;
$test[k]["Generation"]=3;
$test[n]["Generation"]=4;
$test[s]["Generation"]=5;
$test[o]["Generation"]=4;
$test[p]["Generation"]=4;
$test[q]["Generation"]=4;
$test[t]["Generation"]=5;
$test[u]["Generation"]=5;
$test[v]["Generation"]=5;
$test[r]["Generation"]=4;

uasort ($test, "generationsort");

foreach ($test as $key => $value) {
   echo "$key: " . $value["Generation"] . "\n<br>";
}

?>

and here are the results I get:

a: 1 
e: 2 
d: 2 
b: 2 
c: 2 
j: 3 
k: 3 
h: 3 
i: 3 
f: 3 
g: 3 
p: 4 
q: 4 
r: 4 
m: 4 
o: 4 
l: 4 
n: 4 
v: 5 
t: 5 
s: 5 
u: 5

I'm running PHP version 4.3.10-16

Thanks for any help,
Kevin Nowaczyk

[beakerboy]

I figured it's happening because the sort algorithm is rather complicated and isn't comparing sequential rows. The following work, but there may be a simpler answer:

<?php
$test=array();
$test[a]["Generation"]=1;
$test[b]["Generation"]=2;
$test[c]["Generation"]=2;
$test[d]["Generation"]=2;
$test[e]["Generation"]=2;
$test[f]["Generation"]=3;
$test[g]["Generation"]=3;
$test[l]["Generation"]=4;
$test[m]["Generation"]=4;
$test[h]["Generation"]=3;
$test[i]["Generation"]=3;
$test[j]["Generation"]=3;
$test[k]["Generation"]=3;
$test[n]["Generation"]=4;
$test[s]["Generation"]=5;
$test[o]["Generation"]=4;
$test[p]["Generation"]=4;
$test[q]["Generation"]=4;
$test[t]["Generation"]=5;
$test[u]["Generation"]=5;
$test[v]["Generation"]=5;
$test[r]["Generation"]=4;
$newarray = array();
$continue = true;
reset($test);
$pos = 0;
echo count($test);
$genCounter = 1;
while (count($newarray) < count($test)) {
        foreach ($newarray as $key => $value) {
                echo "$key: " . $value["Generation"] . "\n<br>";
        }
        reset($newarray);
        echo "<br>";
        foreach ($test as $key => $value) {
                $generation = $value["Generation"];
                if ($generation == $genCounter) {
                        $newarray[$key]["Generation"]=$generation;
                }
        }
        $genCounter++;
}
?>