PHP 8.4.0 RC2 available for testing

array_column

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

array_columnReturn the values from a single column in the input array

Descrizione

array_column(array $array, int|string|null $column_key, int|string|null $index_key = null): array

array_column() returns the values from a single column of the array, identified by the column_key. Optionally, an index_key may be provided to index the values in the returned array by the values from the index_key column of the input array.

Elenco dei parametri

array

A multi-dimensional array or an array of objects from which to pull a column of values from. If an array of objects is provided, then public properties can be directly pulled. In order for protected or private properties to be pulled, the class must implement both the __get() and __isset() magic methods.

column_key

The column of values to return. This value may be an integer key of the column you wish to retrieve, or it may be a string key name for an associative array or property name. It may also be null to return complete arrays or objects (this is useful together with index_key to reindex the array).

index_key

The column to use as the index/keys for the returned array. This value may be the integer key of the column, or it may be the string key name. The value is cast as usual for array keys (however, prior to PHP 8.0.0, objects supporting conversion to string were also allowed).

Valori restituiti

Returns an array of values representing a single column from the input array.

Log delle modifiche

Versione Descrizione
8.0.0 Objects in columns indicated by index_key parameter will no longer be cast to string and will now throw a TypeError instead.

Esempi

Example #1 Get the column of first names from a recordset

<?php
// Array representing a possible record set returned from a database
$records = array(
array(
'id' => 2135,
'first_name' => 'John',
'last_name' => 'Doe',
),
array(
'id' => 3245,
'first_name' => 'Sally',
'last_name' => 'Smith',
),
array(
'id' => 5342,
'first_name' => 'Jane',
'last_name' => 'Jones',
),
array(
'id' => 5623,
'first_name' => 'Peter',
'last_name' => 'Doe',
)
);

$first_names = array_column($records, 'first_name');
print_r($first_names);
?>

Il precedente esempio visualizzerà:

Array
(
    [0] => John
    [1] => Sally
    [2] => Jane
    [3] => Peter
)

Example #2 Get the column of last names from a recordset, indexed by the "id" column

<?php
// Using the $records array from Example #1
$last_names = array_column($records, 'last_name', 'id');
print_r($last_names);
?>

Il precedente esempio visualizzerà:

Array
(
    [2135] => Doe
    [3245] => Smith
    [5342] => Jones
    [5623] => Doe
)

Example #3 Get the column of usernames from the public "username" property of an object

<?php

class User
{
public
$username;

public function
__construct(string $username)
{
$this->username = $username;
}
}

$users = [
new
User('user 1'),
new
User('user 2'),
new
User('user 3'),
];

print_r(array_column($users, 'username'));
?>

Il precedente esempio visualizzerà:

Array
(
    [0] => user 1
    [1] => user 2
    [2] => user 3
)

Example #4 Get the column of names from the private "name" property of an object using the magic __get() method.

<?php

class Person
{
private
$name;

public function
__construct(string $name)
{
$this->name = $name;
}

public function
__get($prop)
{
return
$this->$prop;
}

public function
__isset($prop) : bool
{
return isset(
$this->$prop);
}
}

$people = [
new
Person('Fred'),
new
Person('Jane'),
new
Person('John'),
];

print_r(array_column($people, 'name'));
?>

Il precedente esempio visualizzerà:

Array
(
    [0] => Fred
    [1] => Jane
    [2] => John
)
If __isset() is not provided, then an empty array will be returned.

add a note

User Contributed Notes 25 notes

up
109
mohanrajnr at gmail dot com
9 years ago
if array_column does not exist the below solution will work.

if(!function_exists("array_column"))
{

function array_column($array,$column_name)
{

return array_map(function($element) use($column_name){return $element[$column_name];}, $array);

}

}
up
65
WARrior
11 years ago
You can also use array_map fucntion if you haven't array_column().

example:

$a = array(
array(
'id' => 2135,
'first_name' => 'John',
'last_name' => 'Doe',
),
array(
'id' => 3245,
'first_name' => 'Sally',
'last_name' => 'Smith',
)
);

array_column($a, 'last_name');

becomes

array_map(function($element){return $element['last_name'];}, $a);
up
38
balbuf
6 years ago
This function does not preserve the original keys of the array (when not providing an index_key).

You can work around that like so:

<?php
// instead of
array_column($array, 'column');

// to preserve keys
array_combine(array_keys($array), array_column($array, 'column'));
?>
up
14
yangmeishu at live dot com
4 years ago
Please note that if you use array_column to reset the index, when the index value is null, there will be different results in different PHP versions, examples
<?php

$array
= [
[
'name' =>'Bob',
'house' =>'big',
],
[
'name' =>'Alice',
'house' =>'small',
],
[
'name' =>'Jack',
'house' => null,
],
];
var_dump(array_column($array,null,'house'));

On 5.6.30, 7.0.0, 7.2.0 (not limited to) get the following results
array(3) {
[
"big"]=>
array(
2) {
[
"name"]=>
string(3) "Bob"
["house"]=>
string(3) "big"
}
[
"small"]=>
array(
2) {
[
"name"]=>
string(5) "Alice"
["house"]=>
string(5) "small"
}
[
0]=>
array(
2) {
[
"name"]=>
string(4) "Jack"
["house"]=>
NULL
}
}

The new index, null will be converted to int, and can be incremented according to the previous index, that is, if Alice "house" is also null, then Alice's new index is "0", Jack's new index is "1"

On 7.1.21, 7.2.18, 7.4.8 (not limited to) will get the following results
array(3) {
[
"Big"]=>
array(
2) {
[
"name"]=>
string(3) "Bob"
["house"]=>
string(3) "Big"
}
[
"small"]=>
array(
2) {
[
"name"]=>
string(5) "Alice"
["house"]=>
string(5) "small"
}
[
""]=>
array(
2) {
[
"name"]=>
string(4) "Jack"
["house"]=>
NULL
}
}

The new index null will be converted to an empty string
up
27
till at etill dot net
9 years ago
Some remarks not included in the official documentation.

1) array_column does not support 1D arrays, in which case an empty array is returned.

2) The $column_key is zero-based.

3) If $column_key extends the valid index range an empty array is returned.
up
4
opencart dot ocfilter at gmail dot com
1 year ago
Array multiple columns:

<?php
function array_columns() {
$args = func_get_args();

$array = array_shift($args);

if (!
$args) {
return
$array;
}

$keys = array_flip($args);

return
array_map(function($element) use($keys) {
return
array_intersect_key($element, $keys);
},
$array);
}
?>
EXAMPLE:
<?php
$products
= [
[
'id' => 2,
'name' => 'Phone',
'price' => 210.3
],
[
'id' => 3,
'name' => 'Laptop',
'price' => 430.12
]
];

print_r(array_columns($products, 'name', 'price'));
?>

Output:

Array
(
[0] => Array
(
[name] => Phone
[price] => 210.3
)

[1] => Array
(
[name] => Laptop
[price] => 430.12
)

)
up
16
nino at recgr dot com
8 years ago
array_column implementation that works on multidimensional arrays (not just 2-dimensional):

<?php
function array_column_recursive(array $haystack, $needle) {
$found = [];
array_walk_recursive($haystack, function($value, $key) use (&$found, $needle) {
if (
$key == $needle)
$found[] = $value;
});
return
$found;
}

Taken from https://github.com/NinoSkopac/array_column_recursive
up
13
ff2 AT hotmail DOT co DOT uk
6 years ago
Because the function was not available in my version of PHP, I wrote my own version and extended it a little based on my needs.

When you give an $indexkey value of -1 it preserves the associated array key values.

EXAMPLE:

$sample = array(
'test1' => array(
'val1' = 10,
'val2' = 100
),
'test2' => array(
'val1' = 20,
'val2' = 200
),
'test3' => array(
'val1' = 30,
'val2' = 300
)
);

print_r(array_column_ext($sample,'val1'));

OUTPUT:

Array
(
[0] => 10
[1] => 20
[2] => 30
)

print_r(array_column_ext($sample,'val1',-1));

OUTPUT:

Array
(
['test1'] => 10
['test2'] => 20
['test3'] => 30
)

print_r(array_column_ext($sample,'val1','val2'));

OUTPUT:

Array
(
[100] => 10
[200] => 20
[300] => 30
)

<?php
function array_column_ext($array, $columnkey, $indexkey = null) {
$result = array();
foreach (
$array as $subarray => $value) {
if (
array_key_exists($columnkey,$value)) { $val = $array[$subarray][$columnkey]; }
else if (
$columnkey === null) { $val = $value; }
else { continue; }

if (
$indexkey === null) { $result[] = $val; }
elseif (
$indexkey == -1 || array_key_exists($indexkey,$value)) {
$result[($indexkey == -1)?$subarray:$array[$subarray][$indexkey]] = $val;
}
}
return
$result;
}
?>
up
1
Sbastien
2 years ago
The counterpart of array_column(), namely create an array from columns, can be done with array_map() :

<?php

// Columns
$lastnames = ['Skywalker', 'Organa', 'Kenobi'];
$firstnames = ['Luke', 'Leia', 'Obiwan'];

// Columns to array
$characters = array_map(
fn (
$l, $f) => ['lastname' => $l, 'firstname' => $f],
$lastnames, $firstnames
);

print_r($characters);

/*
[
0 => ['lastname' => 'Skywalker', 'firstname' => 'Luke']
1 => ['lastname' => 'Organa', 'firstname' => 'Leia']
2 => ['lastname' => 'Kenobi', 'firstname' => 'Obiwan']
]
*/
up
8
miguelfzarth at gmail dot com
8 years ago
<?php
# for PHP < 5.5
# AND it works with arrayObject AND array of objects

if (!function_exists('array_column')) {
function
array_column($array, $columnKey, $indexKey = null)
{
$result = array();
foreach (
$array as $subArray) {
if (
is_null($indexKey) && array_key_exists($columnKey, $subArray)) {
$result[] = is_object($subArray)?$subArray->$columnKey: $subArray[$columnKey];
} elseif (
array_key_exists($indexKey, $subArray)) {
if (
is_null($columnKey)) {
$index = is_object($subArray)?$subArray->$indexKey: $subArray[$indexKey];
$result[$index] = $subArray;
} elseif (
array_key_exists($columnKey, $subArray)) {
$index = is_object($subArray)?$subArray->$indexKey: $subArray[$indexKey];
$result[$index] = is_object($subArray)?$subArray->$columnKey: $subArray[$columnKey];
}
}
}
return
$result;
}
}
?>
up
5
Carlos Granados
8 years ago
Here's a neat little snippet for filtering a set of records based on a the value of a column:

<?php

function dictionaryFilterList(array $source, array $data, string $column) : array
{
$new = array_column($data, $column);
$keep = array_diff($new, $source);

return
array_intersect_key($data, $keep);
}

// Usage:

$users = [
[
'first_name' => 'Jed', 'last_name' => 'Lopez'],
[
'first_name' => 'Carlos', 'last_name' => 'Granados'],
[
'first_name' => 'Dirty', 'last_name' => 'Diana'],
[
'first_name' => 'John', 'last_name' => 'Williams'],
[
'first_name' => 'Betty', 'last_name' => 'Boop'],
[
'first_name' => 'Dan', 'last_name' => 'Daniels'],
[
'first_name' => 'Britt', 'last_name' => 'Anderson'],
[
'first_name' => 'Will', 'last_name' => 'Smith'],
[
'first_name' => 'Magic', 'last_name' => 'Johnson'],
];

var_dump(dictionaryFilterList(['Dirty', 'Dan'], $users, 'first_name'));

// Outputs:
[
[
'first_name' => 'Jed', 'last_name' => 'Lopez'],
[
'first_name' => 'Carlos', 'last_name' => 'Granados'],
[
'first_name' => 'John', 'last_name' => 'Williams'],
[
'first_name' => 'Betty', 'last_name' => 'Boop'],
[
'first_name' => 'Britt', 'last_name' => 'Anderson'],
[
'first_name' => 'Will', 'last_name' => 'Smith'],
[
'first_name' => 'Magic', 'last_name' => 'Johnson']
]

?>
up
5
Anonymous
8 years ago
I added a little more functionality to the more popular answers here to support the $index_key parameter for PHP < 5.5

<?php
// for php < 5.5
if (!function_exists('array_column')) {
function
array_column($input, $column_key, $index_key = null) {
$arr = array_map(function($d) use ($column_key, $index_key) {
if (!isset(
$d[$column_key])) {
return
null;
}
if (
$index_key !== null) {
return array(
$d[$index_key] => $d[$column_key]);
}
return
$d[$column_key];
},
$input);

if (
$index_key !== null) {
$tmp = array();
foreach (
$arr as $ar) {
$tmp[key($ar)] = current($ar);
}
$arr = $tmp;
}
return
$arr;
}
}
?>
up
2
benjam
8 years ago
Note that this function will return the last entry when possible keys are duplicated.

<?php

$array
= array(
array(
'1-1',
'one',
'one',
),
array(
'1-2',
'two',
'one',
),
);

var_dump(array_column($array, $value = 0, $index = 1));
var_dump(array_column($array, $value = 0, $index = 2));

// returns:
/*

array (size=2)
'one' => string '1-1' (length=3)
'two' => string '1-2' (length=3)

array (size=1)
'one' => string '1-2' (length=3)

*/
?>
up
1
1184427175 at qq dot com
7 years ago
//php < 5.5
if(function_exists('array_column'))
{
function array_column($arr_data, $col)
{
$result = array_map(function($arr){return $arr[$col]}, $arr_data);
return $result;
}
}
up
2
antonfedonjuk at gmail dot com
9 years ago
My version is closer to the original than http://github.com/ramsey/array_column
<?php
/**
* Provides functionality for array_column() to projects using PHP earlier than
* version 5.5.
* @copyright (c) 2015 WinterSilence (http://github.com/WinterSilence)
* @license MIT
*/
if (!function_exists('array_column')) {
/**
* Returns an array of values representing a single column from the input
* array.
* @param array $array A multi-dimensional array from which to pull a
* column of values.
* @param mixed $columnKey The column of values to return. This value may
* be the integer key of the column you wish to retrieve, or it may be
* the string key name for an associative array. It may also be NULL to
* return complete arrays (useful together with index_key to reindex
* the array).
* @param mixed $indexKey The column to use as the index/keys for the
* returned array. This value may be the integer key of the column, or
* it may be the string key name.
* @return array
*/
function array_column(array $array, $columnKey, $indexKey = null)
{
$result = array();
foreach (
$array as $subArray) {
if (!
is_array($subArray)) {
continue;
} elseif (
is_null($indexKey) && array_key_exists($columnKey, $subArray)) {
$result[] = $subArray[$columnKey];
} elseif (
array_key_exists($indexKey, $subArray)) {
if (
is_null($columnKey)) {
$result[$subArray[$indexKey]] = $subArray;
} elseif (
array_key_exists($columnKey, $subArray)) {
$result[$subArray[$indexKey]] = $subArray[$columnKey];
}
}
}
return
$result;
}
}
?>
up
1
Rumour
10 months ago
If you want to preserve the array keys AND you want it to work on both object properties and array elements AND you want it to work if some of the arrays/objects in the array do not have the given key/property defined, basically the most ROBUST version you can get, yet quick enough:

<?php
function array_column_keys(array|ArrayAccess $arr, string $col) {
// like array_columns but keeps the keys
//to make it work for objects and arrays

return array_map(fn($e) => (is_countable($e) ? ($e[$col]??null) : null) ?: (is_object($e) ? $e->$col : null), $arr);
}

?>

If a key/property is undefined, the value in the result array will be NULL. You can use array_filter() to filter those out if needed.

<?php

class a {
public
string $a = 'property a';
public
string $b = 'property b';
}

$a1 = new a;
$a2 = new a;
$a2->a = 'plop';

$b = ['one'=> ['a'=>'plop'],
3 => $a1,
4 => $a2,
5 =>[],
'kud'=>new a];

return
array_column_keys($b, 'a');

?>

Returns:

Array
(
[one] => plop
[3] => property a
[4] => something else
[5] =>
[kud] => property a
)
up
2
oleg dot bolden at gmail dot com
2 years ago
Index_key is safely applicable only in cases when corresponding values of this index are unique through over the array. Otherwise only the latest element of the array with the same index_key value will be picked up.

<?php
$records
= array(
array(
'id' => 2135,
'first_name' => 'John',
'last_name' => 'Doe',
'company_id' => 1,
),
array(
'id' => 3245,
'first_name' => 'Sally',
'last_name' => 'Smith',
'company_id' => 1,
),
array(
'id' => 5342,
'first_name' => 'Jane',
'last_name' => 'Jones',
'company_id' => 1,
),
array(
'id' => 5623,
'first_name' => 'Peter',
'last_name' => 'Doe',
'company_id' => 2,
)
);

$first_names = array_column($records, 'first_name', 'company_id');
print_r($first_names);
?>

The above example will output:

<?php
Array
(
[
1] => Jane
[2] => Peter
)
?>

To group values by the same `index_key` in arrays one can use simple replacement for the `array_column` like below example function:

<?php
function arrayed_column(array $array, int|string $column_key, int|string $index_key) {
$output = [];
foreach (
$array as $item) {
$output[$item['index_key']][] = $item['column_key'];
}

return
$output;
}

$first_names = arrayed_column($records, 'first_name', 'company_id');
print_r($first_names);
?>

The output:

<?php
Array
(
[
1] => Array
(
[
0] => John
[1] => Sally
[2] => Jane
)
[
2] => Array
(
[
0] =>Peter
)
)
?>
up
0
Hayley Watson
4 months ago
If an entry in the source array does not have a column_key element then array_column will silently skip that entry and return an array shorter than the source.

If entries can't be uniquely identified by an index_key then there's no way of telling which ones were skipped, as without an index_key array_column returns a plain list.

<?php
$array
= [
[
'a' => '0th', 'b' => 'zero'],
[
'a' => '1st', 'b' => 'one'],
[
'a' => '2nd' /* oops */],
[
'a' => '3rd', 'b'=>'three']];
var_export(array_column($array, 'b'));
var_export(array_column($array, 'b', 'a'));
?>
up
0
Hiranmoy Chatterjee
2 years ago
The following function may be useful to create columns from all values of indexed arrays:

<?php
function array_column_all(array $arrays): array
{
$output = [];
$columnCount = count($arrays[0]);
for (
$i = 0; $i < $columnCount; $i++)
{
$output [] = array_column($arrays, $i);
}
return
$output;
}
?>

Use:
-----
<?php
array_column_all
(
[
[
'A1', 'A2', 'A3'],
[
'B1', 'B2', 'B3'],
[
'C1', 'C2', 'C3'],
]
);
?>

This will output:
-------------------
Array
(
[0] => Array
(
[0] => A1
[1] => B1
[2] => C1
)

[1] => Array
(
[0] => A2
[1] => B2
[2] => C2
)

[2] => Array
(
[0] => A3
[1] => B3
[2] => C3
)

)
up
-2
Nolan chou
8 years ago
if (!function_exists('array_column'))
{
function array_column($input, $column_key=null, $index_key=null)
{
$result = array();
$i = 0;
foreach ($input as $v)
{
$k = $index_key === null || !isset($v[$index_key]) ? $i++ : $v[$index_key];
$result[$k] = $column_key === null ? $v : (isset($v[$column_key]) ? $v[$column_key] : null);
}
return $result;
}
}
up
-3
hypxm at qq dot com
9 years ago
a simple solution:

function arrayColumn(array $array, $column_key, $index_key=null){
if(function_exists('array_column ')){
return array_column($array, $column_key, $index_key);
}
$result = [];
foreach($array as $arr){
if(!is_array($arr)) continue;

if(is_null($column_key)){
$value = $arr;
}else{
$value = $arr[$column_key];
}

if(!is_null($index_key)){
$key = $arr[$index_key];
$result[$key] = $value;
}else{
$result[] = $value;
}

}

return $result;
}
up
-4
kaspar dot wilbuer at web dot de
8 years ago
If you need to extract more than one column from an array, you can use array_intersect_key on each element, like so:

function array_column_multi(array $input, array $column_keys) {
$result = array();
$column_keys = array_flip($column_keys);
foreach($input as $key => $el) {
$result[$key] = array_intersect_key($el, $column_keys);
}
return $result;
}
up
-4
katrinaelaine6 at gmail dot com
7 years ago
array_column() will return duplicate values.

Instead of having to use array_unique(), use the $index_key as a hack.

**Caution: This may get messy when setting the $column_key and/or $index_key as integers.**

<?php

$records
= [
[
'id' => 2135, 'first_name' => 'John' ],
[
'id' => 3245, 'first_name' => 'Sally' ],
[
'id' => 5342, 'first_name' => 'Jane' ],
[
'id' => 5623, 'first_name' => 'Peter' ],
[
'id' => 6982, 'first_name' => 'Sally' ]
];

print_r(array_unique(array_column($records, 'first_name')));

// Force uniqueness by making the key the value.
print_r(array_column($records, 'first_name', 'first_name'));
print_r(array_column($records, 'id', 'first_name'));

// Returns
/*

Array
(
[0] => John
[1] => Sally
[2] => Jane
[3] => Peter
)

Array
(
[John] => John
[Sally] => Sally
[Jane] => Jane
[Peter] => Peter
)

Array
(
[John] => 2135
[Sally] => 6982
[Jane] => 5342
[Peter] => 5623
)

*/

?>
up
-4
marianbucur17 at yahoo dot com
9 years ago
If array_column is not available you can use the following function, which also has the $index_key parameter:

if (!function_exists('array_column')) {
function array_column($array, $column_key, $index_key = null)
{
return array_reduce($array, function ($result, $item) use ($column_key, $index_key)
{
if (null === $index_key) {
$result[] = $item[$column_key];
} else {
$result[$item[$index_key]] = $item[$column_key];
}

return $result;
}, []);
}
}
up
-2
info at mobger dot de
1 year ago
If you want to rearrage an array with two layers (perhaps from database-requests), then use 'array_walk' instead:

<?php

$yamlList
= [
[
'title' => 'hallo ich', 'identifier' => 'ich', 'Klaus'=> 'doof',],
[
'title' => 'hallo du', 'identifier' => 'du', 'Klaus'=> 'doof',],
[
'title' => 'hallo er', 'identifier' => 'er', 'Klaus'=> 'doof',],
];
echo (
'Input'."\n".print_r($yamlList,true)."\n");
array_walk($yamlList, function (&$value, $key) {
$value = [
$value['title'],
$value['identifier'],
];
});
echo (
"\n".'Output'."\n".print_r($yamlList,true)."\n");
?>

The Result
===========
...
Output
Array
(
[0] => Array
(
[0] => hallo ich
[1] => ich
)

[1] => Array
(
[0] => hallo du
[1] => du
)

[2] => Array
(
[0] => hallo er
[1] => er
)

)
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