Stop category repeating

[user_scan]

I like to stop the categories from repeating
here's my code:

foreach($categories as $name[1]=>$identity) {
$identity = trim($identity);
$name = explode("|", $identity);
$num = explode("|", $identity);
echo ("<a href=\"?cat=$num[0]\">$name[1]</a>&nbsp;");

Can anybody help please.

[devinemke]

<?php
$categories = array();
$file = file('/path/to/categories.txt');
foreach ($file as $value)
{
	$explode = explode('|', trim($value));
	if (!isset($categories[$explode[0]])) {echo '<a href="?cat=' . $explode[0] . '">' . $explode[1] . '</a>&nbsp;';}
	$categories[$explode[0]] = $explode[1];  

}
?>

[user_scan]

Thanks for your help.