Natural sorting of PHP array in reverse and not preserving keys

Question

I'm look to naturally sort an array, in reverse order and not preserve the keys. For example, I'd like this array:

[0] => 1-string
[1] => 2-string
[2] => 10-string
[3] => 4-srting
[4] => 3-srting

To end up like this:

[0] => 10-srting
[1] => 4-string
[2] => 3-string
[3] => 2-string
[4] => 1-string

I've got it close with usort($array, 'strnatcmp'); but it's not in reverse order. array_reverse() after doesn't help.

Any ideas?

Is that natural or unnatural ordering? I thought natural was "counting" so it would be 1-string, 10-string, 2-string, 3-string, 4-string and unnatural would be 4-string, 3-string, 2-string, 10-string, 1-string. I have been known to misunderstand things (as i am married and miscommunications happen 24/7), so could you give a more in depth explanation, for i do not understand your ordering system. — ThePrimeagen
– ThePrimeagen, Commented Mar 23, 2012 at 16:06
Natural is 1, 2, 3, 4, 10—which I can do. I now need to get that in reverse order, so: 10, 4, 3, 2, 1. — Phil
– Phil, Commented Mar 23, 2012 at 16:08

VolkerK · Accepted Answer · 2012-03-23 16:10:58Z

8

I'm a bit puzzled about "array_reverse() after doesn't help." because

<?php
echo PHP_VERSION, "\n";

$x = array( 
    '1-string',
    '2-string',
    '10-string',
    '4-srting',
    '3-srting'
);

natsort($x);
$x = array_reverse($x, false);
print_r($x);

prints

5.3.8
Array
(
    [0] => 10-string
    [1] => 4-srting
    [2] => 3-srting
    [3] => 2-string
    [4] => 1-string
)

on my machine

answered Mar 23, 2012 at 16:10

VolkerK

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Comments

Andrew Moore · Accepted Answer · 2012-03-23 16:14:30Z

5

Use the $preserveKeys attribute of array_reverse() to reset the keys as well as reversing the array after a natcasesort().

function rnatcasesort(&$array) {
    natcasesort($array);
    $array = array_reverse($array, false);
}

$values = array('1-string', '2-string', '10-string', '4-string', '3-string');

rnatcasesort($values);

var_dump($values);

/*
array(5) {
  [0]=>
  string(9) "10-string"
  [1]=>
  string(8) "4-string"
  [2]=>
  string(8) "3-string"
  [3]=>
  string(8) "2-string"
  [4]=>
  string(8) "1-string"
}
*/

edited Mar 23, 2012 at 16:14

answered Mar 23, 2012 at 16:08

Andrew Moore

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Comments

AndrewR · Accepted Answer · 2012-03-23 16:12:22Z

3

Use rsort() with the SORT_NATURAL flag.

rsort($array, SORT_NATURAL);

SORT_NATURAL was introduced in PHP 5.4. If you are on a lower version, go with the array_reverse(natsort()) version.

answered Mar 23, 2012 at 16:12

AndrewR

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Comments

Nicola Peluchetti · Accepted Answer · 2012-03-23 16:09:37Z

0

You could do

<?php
$arr  = array("1-string", "2-string", "10-string","4-srting", "3-srting");

function sort_reverse($a, $b){
  $a = (int)$a;
  $b = (int)$b;
  if ($a > $b){
    return -1;
  }
  if ($a < $b){
    return 1;
  }
   return 0;
}
usort($arr, "sort_reverse");
var_dump($arr);

pad here http://codepad.org/6dn81S3f

answered Mar 23, 2012 at 16:09

Nicola Peluchetti

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Comments

user1237595 · Accepted Answer · 2012-03-23 16:11:58Z

0

This works:

$array = array('1-string', '2-string', '10-string', '4-string', '3-string');
natsort($array);
$array = array_reverse($array);
print_r($array);

answered Mar 23, 2012 at 16:11

user1237595

Comments

gurcharan · Accepted Answer · 2018-05-25 17:33:57Z

0

use this function to first do a natural sort and then by using array_reverse to make it in descending order

    function natrsort($array)
    {
      natsort($array);
      return array_reverse($array);
    }
    natrsort($array);

answered May 25, 2018 at 17:33

gurcharan

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Comments

Tchoupi · Accepted Answer · 2012-03-23 16:08:24Z

-1

Doesn't rsort($array) fits your need?

answered Mar 23, 2012 at 16:08

Tchoupi

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1 Comment

Phil Over a year ago

Nope. That gets me 4, 3, 2, 10, 1.

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