How to group array but not create new object? - php

Question

I have an array that looks like this:
array (size=21)
0 => string '2' (length=1)
1 => string '' (length=0)
2 => string '20' (length=2)
3 => string '19' (length=2)
4 => string '14' (length=2)
5 => string '13' (length=2)
6 => string '' (length=0)
7 => null
8 => null
9 => string '20' (length=2)
10 => null
11 => string '10' (length=2)
12 => string '' (length=0)
13 => null
14 => string '13' (length=2)
15 => null
16 => string '' (length=0)
17 => null
18 => null
19 => string '' (length=0)
20 => string '20' (length=2)
And I would like to create a new array from this array by grouping rows with the same string. e.g.
2 => string '20' (length=2) with 20 => string '20' (length=2) and with 9 => string '20' (length=2)
and
5 => string '13' (length=2) with 5 => string '13' (length=2)
etc.
and order the new created array rows based on how many times the string occures there.
Order need to be DESC from the most occurrences to the last like a classic top something chart (The most present strings are first and the least are low)
So, the modified array will look like this:
array (size=21)
0 => string '20' (length=2)
1 => string '13' (length=2)
...
I also need somehow to handle null results e.g. 17 => null to be not incorporated at all in the final array modified result.

Answer 1

This should do the trick:
// Filter the "null results" first
$myarray = array_filter($myarray, create_function('$arg', '
return !is_null($arg);
'));
$occurrences = array_count_values($myarray);
// EDIT: arsort preserves the key => value correlation
arsort($occurrences, SORT_NUMERIC);
var_dump(array_keys($occurrences));

Answer 2

Try this.
$result = array_count_values($a);
arsort($result);
$result = array_keys($result);