How to check if a specific value exists at a specific key in any subarray of a multidimensional array?

Question

I need to search a multidimensional array for a specific value in any of the indexed subarrays.

In other words, I need to check a single column of the multidimensional array for a value. If the value exists anywhere in the multidimensional array, I would like to return true otherwise false

$my_array = array(    
    0 =>  array(  
        "name"   => "john",  
        "id"    =>  4  
    ),  
    1   =>  array(  
        "name" =>  "mark",  
        "id" => 152  
    ), 
    2   =>  array(  
        "name" =>  "Eduard",  
        "id" => 152  
    )
);

I would like to know the fastest and most efficient way to check if the array $my_array contains a value with the key "id". For example, if id => 152 anywhere in the multidimensional array, I would like true.

Answer 1

Nothing will be faster than a simple loop. You can mix-and-match some array functions to do it, but they'll just be implemented as a loop too.

function whatever($array, $key, $val) {
    foreach ($array as $item)
        if (isset($item[$key]) && $item[$key] == $val)
            return true;
    return false;
}

Answer 2

The simplest way is this:

$my_array = array(    
    0 =>  array(  
        "name"   => "john",  
        "id"    =>  4  
    ),  
    1   =>  array(  
        "name" =>  "mark",  
        "id" => 152  
    ), 
    2   =>  array(  
        "name" =>  "Eduard",  
        "id" => 152  
    )
);

if (array_search(152, array_column($my_array, 'id')) !== FALSE) {
  echo 'FOUND!';
} else {
  echo 'NOT FOUND!';
}

Answer 3

** PHP >= 5.5

simply u can use this

$key = array_search(40489, array_column($userdb, 'uid'));

Let's suppose this multi dimensional array:

$userdb=Array
(
(0) => Array
    (
        (uid) => '100',
        (name) => 'Sandra Shush',
        (url) => 'urlof100'
    ),

(1) => Array
    (
        (uid) => '5465',
        (name) => 'Stefanie Mcmohn',
        (pic_square) => 'urlof100'
    ),

(2) => Array
    (
        (uid) => '40489',
        (name) => 'Michael',
        (pic_square) => 'urlof40489'
    )
);

$key = array_search(40489, array_column($userdb, 'uid'));

Answer 4

Here is an updated version of Dan Grossman's answer which will cater for multidimensional arrays (what I was after):

function find_key_value($array, $key, $val)
{
    foreach ($array as $item)
    {
        if (is_array($item) && find_key_value($item, $key, $val)) return true;

        if (isset($item[$key]) && $item[$key] == $val) return true;
    }

    return false;
}

Answer 5

If you have to make a lot of "id" lookups and it should be really fast you should use a second array containing all the "ids" as keys:

$lookup_array=array();

foreach($my_array as $arr){
    $lookup_array[$arr['id']]=1;
}

Now you can check for an existing id very fast, for example:

echo (isset($lookup_array[152]))?'yes':'no';

Answer 6

A good solution can be one provided by @Elias Van Ootegan in a comment that is:

$ids = array_column($array, 'id', 'id');
echo isset($ids[40489])?"Exist":"Not Exist";

I tried it and worked for me, thanks buddy.

Edited

Note: It will work in PHP 5.5+

Answer 7

TMTOWTDI. Here are several solutions in order of complexity.

(Short primer on complexity follows):O(n) or "big o" means worst case scenario where n means the number of elements in the array, and o(n) or "little o" means best case scenario. Long discrete math story short, you only really have to worry about the worst case scenario, and make sure it's not n ^ 2 or n!. It's more a measure of change in computing time as n increases than it is overall computing time. Wikipedia has a good article about computational aka time complexity.

If experience has taught me anything, it's that spending too much time optimizing your programs' little-o is a distinct waste of time better spent doing something - anything - better.

Solution 0: O(n) / o(1) complexity:

This solution has a best case scenario of 1 comparison - 1 iteration thru the loop, but only provided the matching value is in position 0 of the array. The worst case scenario is it's not in the array, and thus has to iterate over every element of the array.

foreach ($my_array as $sub_array) {
    if (@$sub_array['id'] === 152) {
        return true;
    }
}
return false;

Solution 1: O(n) / o(n) complexity:

This solution must loop thru the entire array no matter where the matching value is, so it's always going to be n iterations thru the array.

return 0 < count(
    array_filter(
        $my_array,
        function ($a) {
            return array_key_exists('id', $a) && $a['id'] == 152;
        }
    )
);

Solution 2: O(n log n) / o(n log n) complexity:

A hash insertion is where the log n comes from; n hash insertions = n * log n. There's a hash lookup at the end which is another log n but it's not included because that's just how discrete math works.

$existence_hash = [];
foreach ($my_array as $sub_array) {
    $existence_hash[$sub_array['id']] = true;
}
return @$existence_hash['152'];

Answer 8

I came upon this post looking to do the same and came up with my own solution I wanted to offer for future visitors of this page (and to see if doing this way presents any problems I had not forseen).

If you want to get a simple true or false output and want to do this with one line of code without a function or a loop you could serialize the array and then use stripos to search for the value:

stripos(serialize($my_array),$needle)

It seems to work for me.

Answer 9

As in your question, which is actually a simple 2-D array wouldn't it be better? Have a look-

Let say your 2-D array name $my_array and value to find is $id

function idExists($needle='', $haystack=array()){
    //now go through each internal array
    foreach ($haystack as $item) {
        if ($item['id']===$needle) {
            return true;
        }
    }
    return false;
}

and to call it:

idExists($id, $my_array);

As you can see, it actually only check if any internal index with key_name 'id' only, have your $value. Some other answers here might also result true if key_name 'name' also has $value

Answer 10

I don't know if this is better or worse for performance, but here is an alternative:

$keys = array_map(function($element){return $element['id'];}, $my_array);
$flipped_keys = array_flip($keys);
if(isset($flipped_keys[40489]))
{
    // true
}

Answer 11

array_column returns the values of a single column of an array and we can search for a specific value for those via in_array

if (in_array(152, array_column($my_array, 'id'))) {
    echo 'FOUND!';
} else {
    echo 'NOT FOUND!';
}

Answer 12

You can create a queue of sub-arrays and loop each:

function existsKeyValue($myArray, $key, $value) {
    $queue = [$myArray]; //creating a queue of a single element, which is our outermost array

    //when we reach the count of the queue we looped all inner loops as well and failed to find the item
    for ($index = 0; $index < count($queue); $index++) {
        //Looping the current array, finding the key and the value
        foreach ($queue[$index] as $k => &$v) {
            //If they match the search, then we can return true
            if (($key === $k) && ($value === $v)) {
                return true;
            }
            //We need to make sure we did not already loop our current array to avoid infinite cycles
            if (is_array($v)) $queue[]=$v;
        }
    }
    return false;
}

$my_array = array(    
    0 =>  array(  
        "name"   => "john",  
        "id"    =>  4  
    ),  
    1   =>  array(  
        "name" =>  "mark",  
        "id" => 152  
    ), 
    2   =>  array(  
        "name" =>  "Eduard",  
        "id" => 152  
    )
);

echo var_dump(existsKeyValue($my_array, 'id', 152));

Answer 13

Just use array_column as in below example:

$my_array = [
    [
        "name"  => "john",  
        "id"    =>  4  
    ],  
    [
        "name"  =>  "mark",  
        "id"    => 152  
    ], 
    [
        "name"  =>  "Eduard",  
        "id"    => 152  
    ]
];
var_dump(in_array(152, array_column($my_array, 'id'))); // true

Answer 14

Try with this below code. It should be working fine for any kind of multidimensional array search.

Here you can see LIVE DEMO EXAMPLE

function multi_array_search($search_for, $search_in) {
    foreach ($search_in as $element) {
        if ( ($element === $search_for) ){
            return true;
        }elseif(is_array($element)){
            $result = multi_array_search($search_for, $element);
            if($result == true)
                return true;
        }
    }
    return false;
}

Answer 15

You can use this with only two parameter

function whatever($array, $val) {
    foreach ($array as $item)
        if (isset($item) && in_array($val,$item))
            return 1;
    return 0;
}

Answer 16

different between isset vs array_key_exits What's the difference between isset() and array_key_exists()?

different between == vs === How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?

function specificValue(array $array,$key,$val) {
    foreach ($array as $item)
        if (array_key_exits($item[$key]) && $item[$key] === $val)
            return true;
    return false;
}

Answer 17

function checkMultiArrayValue($array) {
        global $test;
        foreach ($array as $key => $item) {

            if(!empty($item) && is_array($item)) {
                checkMultiArrayValue($item);
            }else {
                if($item)
                 $test[$key] = $item;

            }
        }
        return $test;   
    }

 $multiArray = array(    
                0 =>  array(  
                      "country"   => "",  
                      "price"    => 4,  
                      "discount-price" => 0,  
               ),);

$test = checkMultiArrayValue($multiArray);
echo "<pre>"
print_r($test);

Will return array who have index and value

Answer 18

I wrote the following function in order to determine if an multidimensional array partially contains a certain value.

function findKeyValue ($array, $needle, $value, $found = false){
    foreach ($array as $key => $item){
        // Navigate through the array completely.
        if (is_array($item)){
            $found = $this->findKeyValue($item, $needle, $value, $found);
        }

        // If the item is a node, verify if the value of the node contains
        // the given search parameter. E.G.: 'value' <=> 'This contains the value'
        if ( ! empty($key) && $key == $needle && strpos($item, $value) !== false){
            return true;
        }
    }

    return $found;
}

Call the function like this:

$this->findKeyValue($array, $key, $value);