Getting a particular element from a PHP array?

Question

I have an array in my PHP code which looks like this:

Array
(
[1] => Array
    (
        [subject_id] => 1
        [subject] => Math
        [default_selection] => 1
    )

[2] => Array
    (
        [subject_id] => 2
        [subject] => Physics
        [default_selection] => 0
    )

[3] => Array
    (
        [subject_id] => 3
        [subject] => Chemistry
        [default_selection] => 0
    )

[4] => Array
    (
        [subject_id] => 4
        [subject] => Biology
        [default_selection] => 0
    )

[5] => Array
    (
        [subject_id] => 5
        [subject] => Statistics
        [default_selection] => 0
    )

)

I would like to get the value of [subject] where [subject_id]= 2. Is there any direct/shortcut to do this in PHP or I need to run a foreach loop ?

h2ooooooo · Accepted Answer · 2013-11-26 14:05:47Z

2

If you need to do this just once on the same data, simply run a foreach loop:

<?php
    $foundArray = null;

    foreach ($array as $subArray) {
        if ($subArray['subject_id'] == 2) {
            $foundArray = $subArray;
            break;
        }
    }

    var_dump($foundArray);
?>

If you need to check subject_id's a lot with the same data (in the same request), you can associate your key with the subject_id and refer to it that way:

<?php
    $assoc = array();

    foreach ($array as $subArray) {
        $assoc[$subArray['subject_id']] = $subArray;
    }

    var_dump($assoc[2]);
    var_dump($assoc[3]);
    var_dump($assoc[4]);
?>

answered Nov 26, 2013 at 14:05

h2ooooooo

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Comments

Community · Accepted Answer · 2023-11-17 20:33:26Z

1

you can use array_map

Use this function:

function getSubject($subject) {
   if  ($subject['subject_id'] == 2) return $subject; 
}

Usage:

$subjects = array_map('getSubject', $array);
var_dump($subjects);

Reference: Get specific key value pair from multidimensional array

edited Nov 17, 2023 at 20:33

CommunityBot

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answered Nov 26, 2013 at 14:10

Uncle Aaroh

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Comments

Spudley · Accepted Answer · 2013-11-26 14:17:06Z

1

New in PHP 5.5 is the array_column() function, which will probably acheive what you're asking for (ie searching without using foreach()):

$searchForSubjectID = 2;
$index = array_search($searchForSubjectID, array_column($data, 'subject_id'));
$subject = $data[$index]['subject'];

print $subject;  //prints 'Physics'

If you're not on PHP 5.5 yet, there is a compatibility library for this function.

answered Nov 26, 2013 at 14:17

Spudley

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Comments

rockerest · Accepted Answer · 2013-11-26 14:11:55Z

0

You can use array_filter to select the correct element:

<?php
    function getSecondSubject( $element ){
        return $element["subject_id"] == 2;
    }

    $only_subject_two = array_filter( $all_subjects, "getSecondSubject" );

    $subject = $only_subject_two["subject"];
?>

You can use some trickiness (like a variable) to make the subject_id you're looking for variable, if you need that.

answered Nov 26, 2013 at 14:11

rockerest

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