Sorting a array's numeric values without re-indexing (PHP)

Question

What I'm doing is this:

• I get a list of ID values (numeric) from the DB and store it into an array (1, 2, 2, ...)
• I then count the duplicates with array_count_values. this outputs ([1]=>1, [2]=>2, ...)
• I then want to reorder the array in a descending order via the count
• I then just use array_keys($array) to get the IDs in a count ordered list.

I once used array_multisort for a similar function but in that case the keys were strings ('a'=>2). The problem now is that I'm using numeric keys and multisort re-indexes the keys to 1, 2, 3 because the keys holding the count value are numeric IDs. This of course screws the purpose 'cause I can't identify anything anymore..

Anyway, here's what I'm roughly doing now:

$array = array(3, 1, 2, 3, 2, 3);
// count the IDs [0]=>3, [1]=>1, [2]=>2

$count = array_count_values($array);

// sort and screw up the id's: [0]=>3 [1]=>1 [2]=>2
array_multisort($count);

Something tells me that there's a better way of approaching this?

Answer 1

Try asort instead of array_multisort as it maintains the original index association.

Answer 2

Guessing from your first sentence:

I get a list of ID values (numeric) from the DB and store it into an array (1, 2, 2, ...)

perhaps you could do the sorting whilst querying, something like this:

SELECT id, COUNT(id) AS quantity FROM table GROUP BY id ORDER BY quantity DESC

Answer 3

Why do you need to do it with php? Change your SQL statement to give you the correct results. something like

select ID, count(another_col) as occurrence
from table
group by ID
sort by occurrence

For the right SQL syntax see http://www.techonthenet.com/sql/group_by.php

edit: ups missed the sorting criteria. It must be by occurrence and not by ID

Answer 4

As others mentioned, if you can get the data sorted from the database, it might be better. If You want to do it in PHP and need reversed order, use [arsort][1].