Grab array values with keys in specified range - PHP 5.5

Question

In an array of arbitrary order and keys, as below

$myArray = array(
    1  => 'foo',
    4  => 'bar',
    6  => 'foobar',
    24 => 'barfoo',
    30 => 'fizz',
    35 => 'buzz',
    50 => 'fizzbuzz'
);

How can I get a segment of the array by a key range, for example, every item with a key between 5 and 40

Something like array_range($myArray, 5, 40);

Expected output: array(6 => 'foobar', 24 => 'barfoo', 30 => 'fizz', 35 => 'buzz')

This is similar to How to use array_filter() to filter array keys? but in this case, I am restricted to PHP 5.5.

Are all the array values unique or do you expect duplicates? — edcs
– edcs, Commented Feb 2, 2017 at 15:45
Possible duplicate of PHP: How to use array_filter() to filter array keys? — random_user_name
– random_user_name, Commented Feb 2, 2017 at 15:45
You can array_flip() your array (which swaps the keys and values around), array_filter() the flipped array and then array_flip() the result back. Of course that will only work 100% reliably with arrays that don't contain any duplicate values but if you can meet that requirement then it should work. — GordonM
– GordonM, Commented Feb 2, 2017 at 16:34

AbraCadaver · Accepted Answer · 2017-02-02 16:18:19Z

3

Define a range of keys in an array and then compute the intersection of keys:

$range  = array_flip(range(5, 40));
$result = array_intersect_key($myArray, $range);

One liner:

$result = array_intersect_key($myArray, array_flip(range(5, 40)));

Optionally to fill the range array (I just thought of the other one first and it's shorter):

$range = array_fill_keys(range(5, 40), 1);

If you want specific keys and not a range, just define an array of keys or values and flip:

$range = array_flip(array(6, 24, 50));
//or
$range = array(6=>1, 24=>1, 50=>1);

edited Feb 2, 2017 at 16:18

answered Feb 2, 2017 at 15:45

AbraCadaver

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1 Comment

Eamonn Over a year ago

This is the most concise answer, but I kept getting out of memory issues with it :(

Community · Accepted Answer · 2017-05-23 12:01:39Z

2

If PHP version is under 5.6, upgrade your version of PHP - 5.5 is not even supported any longer. If you can't upgrade PHP, then clearly AbraCadaver's answer is the one to use.

This requires PHP 5.6+, but was answered before the PHP version was clarified in the question, so I will leave it for reference.

Using array_filter - so long as the PHP version is above 5.6:

$allowed_range = [ 'min' => 5, 'max' => 40 ];
$filtered = array_filter(
    $myArray,
    function ( $key ) use ( $allowed_ranged ) {
        return ( $key >= $allowed_range[ 'min' ] && $key <= $allowed_range[ 'max' ] );
    },
    ARRAY_FILTER_USE_KEY
);

edited May 23, 2017 at 12:01

CommunityBot

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answered Feb 2, 2017 at 15:48

random_user_name

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6 Comments

Eamonn Over a year ago

I am the developer, not the system admin. When it's under my control, I exclusively use PHP 7 as an absolute minimum, but things aren't always that way unfortunately.

Eamonn Over a year ago

Upvoted for prosperity though. Anyone using outdated PHP should update immediately.

random_user_name Over a year ago

Understood - I put this here for future visitors as much as anything else, so not any sort of commentary on you or your skills! I am a developer also, and know that we often have our hands tied...

GordonM Over a year ago

Google App Engine is stuck on 5.5 so if you're running applications in Google's cloud then you're stuck with that version at least until google pull their finger out.

random_user_name Over a year ago

@GordonM - wow that's amazing that Google would have people locked down to old unsupported versions :\

|

Progrock · Accepted Answer · 2017-02-02 16:31:49Z

1

Just iterate the array, and use a condition to build a filtered array (here assuming an inclusive range):

<?php
$in = array(
    1  => 'foo',
    4  => 'bar',
    6  => 'foobar',
    24 => 'barfoo',
    30 => 'fizz',
    35 => 'buzz',
    50 => 'fizzbuzz'
);

$out = [];
foreach($in as $k => $v)
{
    if($k >= 5 && $k <= 40) {
        $out[$k] = $v;
    }
}
var_dump($out);

Output:

array (size=4)
  6 => string 'foobar' (length=6)
  24 => string 'barfoo' (length=6)
  30 => string 'fizz' (length=4)
  35 => string 'buzz' (length=4)

answered Feb 2, 2017 at 16:31

Progrock

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3 Comments

Eamonn Over a year ago

Correct and working, but the accepted answer is much more concise.

Eamonn Over a year ago

More understandable at a glance, I'll give you that.

Eamonn Over a year ago

Changed this to correct answer, as I had to use it in order to keep within memory limits in larger arrays with much larger ranges.

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