natsort
(PHP 4, PHP 5)
natsort — Sort an array using a "natural order" algorithm
Description
bool natsort
( array
&$array
)This function implements a sort algorithm that orders alphanumeric strings in the way a human being would while maintaining key/value associations. This is described as a "natural ordering". An example of the difference between this algorithm and the regular computer string sorting algorithms (used in sort()) can be seen in the example below.
Parameters
-
array -
The input array.
Return Values
Returns TRUE on success or FALSE on failure.
Changelog
| Version | Description |
|---|---|
| 5.2.10 | Zero padded numeric strings (e.g., '00005') now essentially ignore the 0 padding. |
Examples
Example #1 natsort() examples demonstrating basic usage
<?php
$array1 = $array2 = array("img12.png", "img10.png", "img2.png", "img1.png");
asort($array1);
echo "Standard sorting\n";
print_r($array1);
natsort($array2);
echo "\nNatural order sorting\n";
print_r($array2);
?>
The above example will output:
Standard sorting
Array
(
[3] => img1.png
[1] => img10.png
[0] => img12.png
[2] => img2.png
)
Natural order sorting
Array
(
[3] => img1.png
[2] => img2.png
[1] => img10.png
[0] => img12.png
)
For more information see: Martin Pool's » Natural Order String Comparison page.
Example #2 natsort() examples demonstrating potential gotchas
<?php
echo "Negative numbers\n";
$negative = array('-5','3','-2','0','-1000','9','1');
print_r($negative);
natsort($negative);
print_r($negative);
echo "Zero padding\n";
$zeros = array('09', '8', '10', '009', '011', '0');
print_r($zeros);
natsort($zeros);
print_r($zeros);
echo "Other characters interfering\n";
$images_oops = array('image_1.jpg','image_12.jpg', 'image_21.jpg', 'image_4.jpg');
print_r($images_oops);
natsort($images_oops);
print_r($images_oops);
echo "Sort by keys\n";
$smoothie = array('orange' => 1, 'apple' => 1, 'yogurt' => 4, 'banana' => 4);
print_r($smoothie);
uksort( $smoothie, 'strnatcmp');
print_r($smoothie);
?>
The above example will output:
Negative numbers
Array
(
[0] => -5
[1] => 3
[2] => -2
[3] => 0
[4] => -1000
[5] => 9
[6] => 1
)
Array
(
[2] => -2
[0] => -5
[4] => -1000
[3] => 0
[6] => 1
[1] => 3
[5] => 9
)
Zero padding
Array
(
[0] => 09
[1] => 8
[2] => 10
[3] => 009
[4] => 011
[5] => 0
)
Array
(
[5] => 0
[1] => 8
[3] => 009
[0] => 09
[2] => 10
[4] => 011
)
Other characters interfering
Array
(
[0] => image_1.jpg
[1] => image_12.jpg
[2] => image_21.jpg
[3] => image_4.jpg
)
Array
(
[0] => image_1.jpg
[3] => image_4.jpg
[1] => image_12.jpg
[2] => image_21.jpg
)
Sort by keys
Array
(
[orange] => 1
[apple] => 1
[yogurt] => 4
[banana] => 4
)
Array
(
[apple] => 1
[banana] => 4
[orange] => 1
[yogurt] => 4
)
See Also
- natcasesort() - Sort an array using a case insensitive "natural order" algorithm
- The comparison of array sorting functions
- strnatcmp() - String comparisons using a "natural order" algorithm
- strnatcasecmp() - Case insensitive string comparisons using a "natural order" algorithm
- PHP Руководство
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- sort
- uasort
- uksort
- usort
Коментарии
Reverse Natsort:
function rnatsort($a, $b) {
return -1 * strnatcmp($a, $b);
}
usort($arr, "rnatsort");
About the reverse natsort.. Maybe simpler to do :
function strrnatcmp ($a, $b) {
return strnatcmp ($b, $a);
}
To make a reverse function, you can simply:
function rnatsort(&$a){
natsort($a);
$a = array_reverse($a, true);
}
For those who want to natsort a 2d-array on the first element of each sub-array, the following few lines should do the job.
<?php
function natsort2d(&$aryInput) {
$aryTemp = $aryOut = array();
foreach ($aryInput as $key=>$value) {
reset($value);
$aryTemp[$key]=current($value);
}
natsort($aryTemp);
foreach ($aryTemp as $key=>$value) {
$aryOut[] = $aryInput[$key];
}
$aryInput = $aryOut;
}
?>
Under limited testing, natsort() appears to work well for IP addresses. For my needs, it is far less code than the ip2long()/long2ip() conversion I was using before.additional to the code posted by justin at redwiredesign dot com (which I found very usefull) here is a function that sorts complex arrays like this:
<?
$array['test0'] = array('main' => 'a', 'sub' => 'a');
$array['test2'] = array('main' => 'a', 'sub' => 'b');
$array['test3'] = array('main' => 'b', 'sub' => 'c');
$array['test1'] = array('main' => 'a', 'sub' => 'c');
$array['test4'] = array('main' => 'b', 'sub' => 'a');
$array['test5'] = array('main' => 'b', 'sub' => 'b');
?>
or
<?
$array[0] = array('main' => 1, 'sub' => 1);
$array[2] = array('main' => 1, 'sub' => 2);
$array[3] = array('main' => 2, 'sub' => 3);
$array[1] = array('main' => 1, 'sub' => 3);
$array[4] = array('main' => 2, 'sub' => 1);
$array[5] = array('main' => 2, 'sub' => 2);
?>
on one or more columns.
the code
<? $array = array_natsort_list($array,'main','sub'); ?>
will result in $array being sortet like this:
test0,test2,test1,test4,test5,test3
or
0,2,1,4,5,3.
you may even submit more values to the function as it uses a variable parameter list. the function starts sorting on the last and the goes on until the first sorting column is reached.
to me it was very usefull for sorting a menu having submenus and even sub-submenus.
i hope it might help you too.
here is the function:
<?
function array_natsort_list($array) {
// for all arguments without the first starting at end of list
for ($i=func_num_args();$i>1;$i--) {
// get column to sort by
$sort_by = func_get_arg($i-1);
// clear arrays
$new_array = array();
$temporary_array = array();
// walk through original array
foreach($array as $original_key => $original_value) {
// and save only values
$temporary_array[] = $original_value[$sort_by];
}
// sort array on values
natsort($temporary_array);
// delete double values
$temporary_array = array_unique($temporary_array);
// walk through temporary array
foreach($temporary_array as $temporary_value) {
// walk through original array
foreach($array as $original_key => $original_value) {
// and search for entries having the right value
if($temporary_value == $original_value[$sort_by]) {
// save in new array
$new_array[$original_key] = $original_value;
}
}
}
// update original array
$array = $new_array;
}
return $array;
}
?>
I got caught out through naive use of this feature - attempting to sort a list of image filenames from a digital camera, where the filenames are leading zero padded (e.g. DSCF0120.jpg) , will not sort correctly.Maybe the example could be modified to exhibit this behaviour
(e.g. set array to -img0120.jpg','IMG0.png', 'img0012.png', 'img10.png', 'img2.png', 'img1.png', 'IMG3.png)
If the example hadn't used images I would have coded it correctly first time around!
There's one little thing missing in this useful bit of code posted by mbirth at webwriters dot de:
<?php
function natsort2d(&$aryInput) {
$aryTemp = $aryOut = array();
foreach ($aryInput as $key=>$value) {
reset($value);
$aryTemp[$key]=current($value);
}
natsort($aryTemp);
foreach ($aryTemp as $key=>$value) {
$aryOut[$key] = $aryInput[$key];
// --------^^^^ add this if you want your keys preserved!
}
$aryInput = $aryOut;
}
?>
This function can be very usefull, but in some cases, like if you want to sort a MySQL query result, it's important to keep in mind that MySQL as built'in sorting functions which are way faster than resorting the result using a complex php algorythm, especially with large arrays.
ex; 'SELECT * FROM `table` ORDER BY columnName ASC, columnName2 DESC'
Here's a handy function to sort an array on 1 or more columns using natural sort:
<?php
// Example: $records = columnSort($records, array('name', 'asc', 'addres', 'desc', 'city', 'asc'));
$globalMultisortVar = array();
function columnSort($recs, $cols) {
global $globalMultisortVar;
$globalMultisortVar = $cols;
usort($recs, 'multiStrnatcmp');
return($recs);
}
function multiStrnatcmp($a, $b) {
global $globalMultisortVar;
$cols = $globalMultisortVar;
$i = 0;
$result = 0;
while ($result == 0 && $i < count($cols)) {
$result = ($cols[$i + 1] == 'desc' ? strnatcmp($b[$cols[$i]], $a[$cols[$i]]) : $result = strnatcmp($a[$cols[$i]], $b[$cols[$i]]));
$i+=2;
}
return $result;
}
?>
Greetings,
- John
there is another rnatsort function lower on the page, but it didn't work in the context i needed it in.
reasoning for this:
sorting naturally via the keys of an array, but needing to reverse the order.
function rnatsort ( &$array = array() )
{
$keys = array_keys($array);
natsort($keys);
$total = count($keys) - 1;
$temp1 = array();
$temp2 = array();
// assigning original keys to an array with a backwards set of keys, to use in krsort();
foreach ( $keys as $key )
{
$temp1[$total] = $key;
--$total;
}
ksort($temp1);
// setting the new array, with the order from the krsort() and the values of original array.
foreach ( $temp1 as $key )
{
$temp2[$key] = $array[$key];
}
$array = $temp2;
}
There's no need to include your own API code to natsort an associative array by key. PHP's in-built functions (other than natsort) can do the job just fine:
<?php
uksort($myArray, "strnatcmp");
?>
natsort might not act like you would expect with zero padding, heres a quick sample.
<?php
$array = array('09', '8', '10', '009', '011');
natsort($array);
?>
/*
Array
(
[3] => 009
[4] => 011
[0] => 09
[1] => 8
[2] => 10
)
*/
Note: negatives number.<?php
$a = array(-5,-2,3,9);
natsort($a);
print_r($a);
?>
Will output:
Array ( [1] => -2 [0] => -5 [2] => 3 [3] => 9 )
Be careful of the new behaviour in 5.2.10 version.
See the following sample:
<?php
$array = array('1 bis', '10 ter', '0 PHP', '0', '01', '01 Ver', '0 ', '1 ', '1');
natsort($array);
echo '<pre>';
print_r($array);
echo '</pre>';
?>
5.2.6-1 will output:
Array
(
[3] => 0
[6] => 0
[2] => 0 OP
[4] => 01
[5] => 01 Ver
[8] => 1
[7] => 1
[0] => 1 bis
[1] => 10 ter
)
5.2.10 will output:
Array
(
[6] => 0
[3] => 0
[8] => 1
[4] => 01
[7] => 1
[5] => 01 Ver
[0] => 1 bis
[1] => 10 ter
[2] => 0 OP
)
Greetings
To naturally sort by array key, the uksort function can be used.
<?php
echo "Sort by keys\n";
$smoothie = array('orange' => 1, 'apple' => 1, 'yogurt' => 4, 'banana' => 4);
print_r($smoothie);
uksort( $smoothie, 'strnatcmp');
print_r($smoothie)
?>
Output:
Sort by keys
Array
(
[orange] => 1
[apple] => 1
[yogurt] => 4
[banana] => 4
)
Array
(
[apple] => 1
[banana] => 4
[orange] => 1
[yogurt] => 4
)
See function.uksort for more information about uksort and http://php.net/strnatcmp for usage of strnatcmp.
This made me waste a lot of my precious youth ... natsort() is buggy if all numbers don't have the same number of decimal places.
(php 5.6.4-4ubuntu6.2)
<?php
$different_decimal_places_in_values = array('D'=>'13.59', '14.6' => '14.6', 'C-' => '14.19');
natsort($a);
var_dump($a);
/*echoes
array(3) {
'D' =>
string(5) "13.59"
'14.6' =>
string(4) "14.6" <----------- badly ordered
'C-' =>
string(5) "14.19"
}*/
?>
While this
<?php
$same_num_decimal_places_in_values = array('D'=>'13.59', '14.6' => '14.60', 'C-' => '14.19'); natsort($a); var_dump($a);
/*echoes
array(3) {
'D' =>
string(5) "13.59"
'C-' =>
string(5) "14.19"
'14.6' =>
string(5) "14.60" <--------- that is the correct position
}
*/
?>
As noted in other notes, natsort() does _not_ always return the expected sort order. It seems especially buggy when decimals or 0 padding is used. I've filed this bug report on the issue:https://bugs.php.net/bug.php?id=74672
$array1 = $array2 = array('IMG0.png', 'img12.png', 'img10.png', 'img2.png', 'img1.png', 'IMG3.png');
natsort($array1);
echo "\n natsort(); \n";
print_r($array1);
sort($array2, SORT_NATURAL);
echo "\n sort() with SORT_NATURAL Option\n";
print_r($array2);
Ouput:
natsort();
Array
(
[0] => IMG0.png
[5] => IMG3.png
[4] => img1.png
[3] => img2.png
[2] => img10.png
[1] => img12.png
)
sort() with SORT_NATURAL Option
Array
(
[0] => IMG0.png
[1] => IMG3.png
[2] => img1.png
[3] => img2.png
[4] => img10.png
[5] => img12.png
)
as we can see it's the same values but not the same keys, and also it's same for sort($array1, SORT_NATURAL | SORT_FLAG_CASE); and natcasesort($array2)