CODEWITHSUNDEEP
phparrayssortingcustom-sort
Steve Ray
Steve Ray

Reputation: 158

Sort an array of strings as if mid-string numbers are at the end of the string

I have an array of values that I'd like to sort alphabetically, but with numbers sorted after characters.

For instance, given the following strings:

$array = [
    'Core 2 Duo',
    'Core Duo',
    'Core Quad',
    'Core 4 Quad'
];

Desired result:

[
    'Core Duo',
    'Core 2 Duo',
    'Core Quad',
    'Core 4 Quad'
]

PHP's sort() function is not suitable because it puts the mid-string numbers first, like this:

[
    'Core 2 Duo',
    'Core 4 Quad',
    'Core Duo',
    'Core Quad'
]

Natural sorting returns the same results as regular sorting.

Is there any way to tell PHP something like, "If you encounter a number, sort it as if it comes at the end of the sting"?

Upvotes: 2

Views: 1285

Answers (3)

mickmackusa
mickmackusa

Reputation: 47900

For reliability, use preg_replace() to move all of the numeric substrings to the back of the string, then use natural sorting inside of a array_multisort() call. (Demo)

$array = [
    'Core 2 Duo',
    'Core Duo',
    'Core Quad',
    'Core 12 Duo',
    'Core 11 Duo',
    'Core 102 Duo',
    'Core 1 Duo',
    'Core 2 Quad'
];

array_multisort(
    preg_replace('/( \d+)(.*)/', '$2$1', $array),
    SORT_NATURAL,
    $array
);
var_export($array);

Output:

array (
  0 => 'Core Duo',
  1 => 'Core 1 Duo',
  2 => 'Core 2 Duo',
  3 => 'Core 11 Duo',
  4 => 'Core 12 Duo',
  5 => 'Core 102 Duo',
  6 => 'Core Quad',
  7 => 'Core 2 Quad',
)

Upvotes: 0

MD SHAHIDUL ISLAM
MD SHAHIDUL ISLAM

Reputation: 14523

Here is your solution:

<?php

$array = array('Core 2 Duo', 'Core Duo', 'Core Quad', 'Core 4 Quad');

$tempArray = array();
foreach($array as $key=>$value) {
    $exp = explode(" ",$value); 
    if(count($exp)==3) {
        $tempArray[$key] = $exp[0]." ".$exp[2]." ".$exp[1];
    } else {
        $tempArray[$key] = $exp[0]." ".$exp[1]." "."-1";
    }
}

asort($tempArray);

$sortedArray = array();
foreach($tempArray as $key=>$value) {
    $sortedArray[] = $array[$key];
}

print_r($sortedArray);

?>

Output:

Array
(
    [0] => Core Duo
    [1] => Core 2 Duo
    [2] => Core Quad
    [3] => Core 4 Quad
)

Upvotes: 1

Ja͢ck
Ja͢ck

Reputation: 173572

It seems that what you're after is a function that pushes all numeric elements of your strings to the back, e.g. "Core 2 Duo" => "Core Duo 2".

// moves numeric parts of the string to the back
function transform($s)
{
        $parts = explode(' ', $s);
        foreach (array_filter($parts, 'is_numeric') as $key => $value) {
                unset($parts[$key]);
                $parts[] = $value;
        }
        return join(' ', $parts);
}

// natural sort on transformed strings
function cmp($a, $b)
{
    return strnatcmp(transform($a), transform($b));
}

$a = array('Core 2 Duo', 'Core Duo', 'Core Quad', 'Core 2 Quad');

usort($a, 'cmp');

print_r($a);

Upvotes: 3

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