Find duplicate items in an array (how to)

Thursday 11 September 2008 8:53:44 am

If you worked directly with MySQL, you could do with something like this:

SELECT COUNT(real_id), real_id, duplicate_id 
FROM table 
GROUP BY duplicate_id

and probably even limit the results to only duplicates.

In PHP, I'm not sure if it is fast, but should work:

<?php
$IDArray = array(...); // here are all the IDs, including duplicates
$IDCount = array_count_values( $IDArray );
$duplicateArray = array();
foreach( $IDCount as $id => $count )
{
    if( $count > 1 )
    {
        array_push( $duplicateArray, $id );
    }
}
$duplicateArray = ... // these are duplicate ids...
?>

http://pl.php.net/manual/pl/function.array-count-values.php

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Saturday 13 September 2008 12:21:12 pm

Hi!

What I would like to do is to allow my client to make a click on a link that will search all products unique codes and tell him wich items have the same code (an error while populating the site)...

So I must search all products codes, select all that have same ID's and show them to my customer.

This algorithm should be run on demand as it will slow down the site, I cannot aford to do such a thing each time an item is added.

Unique will eliminate duplicate entryes within the array THIS IS NOT WHAT I WOULD LIKE TO DO!

Unique could be used before running the "duplicate search code" to see if it has duplicate codes (comparing the array|count before with an array|count|unique)

any hints
thanks

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