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question about manipulating an array

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Aquilo:
I need to find a cleaner way to randomly truncate an array to 20 keys from a few hundered this works but runs at like .300+ seconds, could anyone offer a better way to do this?

<?php
$f = file_get_contents('words.txt');
$exp = explode('|', $f);
$arr = array_unique($exp);

   while (count($arr) > 20)
   {
      range(1, count($arr)-1);
      srand((float)microtime()*1010101975);
      shuffle($arr);
      array_pop($arr);
   }

   while (list ($key, $val) = each($arr))
   {
      echo $val,',';
   }
?>

Thanks for any feedback!

[Unknown]:
Why not just pick 20 random elements?

-[Unknown]

Iridium:
You could shuffle then take the first 20 items (taking random 20 makes no difference).

I would also like to point out that the pseudo-random number generator should be seeded once (and as of PHP 4.2.0, doesn't need seeding at all)

Seeding multiple times often results in surprisingly un-random values (I don't know why this occurs, but there's a lot of pseudo-random number generating theory behind it).

Anguz:
yeah, like they said, you could do something like


--- Code: ---<?php
$arr1 = explode(&#39;|&#39;, file_get_contents(&#39;words.txt&#39;));
$arr1 = shuffle(array_unique($arr1));

for($i = 0; $i < 20; $i++)
    $arr2[] = $arr1[$i];

$str = &#39;&#39;;
foreach($arr2 as $a)
    $str .= $a . &#39;, &#39;;
echo $str;
?>
--- End code ---

I don't know how fast it'd be though

if you're using ob, I think the echo part'd be faster as


--- Code: ---<?php
foreach($arr2 as $a)
    echo $a,&#39;, &#39;;
?>
--- End code ---

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