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);
}
}
array_column
(PHP 5 >= 5.5.0, PHP 7, PHP 8)
array_column — 入力配列から単一のカラムの値を返す
説明
array_column() は、
配列 array の中から
column_key で指定した単一のカラムの値を返します。
オプションで index_key も指定できます。
これを指定すると、
入力配列内のカラム index_key の値をキーとし、
カラム column_key を値とした配列が返されます。
パラメータ
array-
値を取り出したい多次元配列 (あるいはオブジェクトの配列)。 オブジェクトの配列を指定した場合は、public プロパティはそのまま取得できます。 protected や private なプロパティを取得したい場合は、そのクラスがマジックメソッド __get() および __isset() を実装している必要があります。
column_key-
値を返したいカラム。 取得したいカラムの番号を整数値で指定することもできるし、 連想配列のキーやプロパティの名前を指定することもできます。
nullを指定すると、配列やオブジェクト全体を返します (index_keyとの組み合わせで、配列の並べ替えをするときに便利です)。 index_key-
返す配列のインデックス/キーとして使うカラム。 カラム番号を表す整数値、あるいはキーの名前を表す文字列になります。 この値は、いつものように配列のキーとして キャストされます。 (PHP 8.0.0 より前のバージョンでは、 文字列への変換をサポートしているオブジェクトも許可されていました)
戻り値
入力配列の単一のカラムを表す値の配列を返します。
変更履歴
| バージョン | 説明 |
|---|---|
| 8.0.0 |
index_key で指定されたカラムにオブジェクトが含まれていても、
文字列にキャストされなくなりました。
代わりに、TypeError が発生するようになっています。
|
例
例1 レコードセットからのファーストネームの取得
<?php
// データベースから返ってきたレコードセットの例
$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);
?>上の例の出力は以下となります。
Array
(
[0] => John
[1] => Sally
[2] => Jane
[3] => Peter
)
例2 レコードセットから姓を取得し、"id"で並べ替える例
<?php
// 先ほどの例と同じ $records 配列を使います
$last_names = array_column($records, 'last_name', 'id');
print_r($last_names);
?>上の例の出力は以下となります。
Array
(
[2135] => Doe
[3245] => Smith
[5342] => Jones
[5623] => Doe
)
例3 オブジェクトの public プロパティ "username" からユーザー名を取得する例
<?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'));
?>上の例の出力は以下となります。
Array
(
[0] => user 1
[1] => user 2
[2] => user 3
)
例4 オブジェクトの private プロパティ "name" から、マジックメソッド __get() を使って名前を取得する例
<?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'));
?>上の例の出力は以下となります。
Array
(
[0] => Fred
[1] => Jane
[2] => John
)
add a note
User Contributed Notes 25 notes
mohanrajnr at gmail dot com ¶
8 years ago
WARrior ¶
10 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);
ff2 AT hotmail DOT co DOT uk ¶
5 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;
}
?>
yangmeishu at live dot com ¶
3 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
balbuf ¶
5 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'));
?>
till at etill dot net ¶
8 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.
nino at recgr dot com ¶
7 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
antonfedonjuk at gmail dot com ¶
8 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 $result;
}
}
?>
miguelfzarth at gmail dot com ¶
7 years ago
<?php
# for PHP < 5.5
# AND it works with arrayObject AND array of objects
if (!function_exists('array_column')) {
function array_column($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;
}
}
?>
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 $arr;
}
}
?>
1184427175 at qq dot com ¶
6 years ago
//php < 5.5
if(function_exists('array_column'))
{
function array_column($arr_data, $col)
{
$result = array_map(function($arr){return $arr[$col]}, $arr_data);
return $result;
}
}
Carlos Granados ¶
7 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']
]
?>
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
)
*/
?>
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;
}
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, $index = 2));
// returns:
/*
array (size=2)
'one' => string '1-1' (length=3)
'two' => string '1-2' (length=3)
array (size=1)
'one' => string '1-2' (length=3)
*/
?>
Nolan chou ¶
8 years ago
if (!function_exists('array_column'))
{
function array_column($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;
}
}
kiler129 @ nowhere ¶
9 years ago
Please note this function accepts 2D-arrays ONLY, and silently returns empty array when non-array argument is provided.
Code:
class testObject {
public $a = 123;
}
$testArray = [new testObject(), new testObject(), new testObject()];
$result = array_column($testArray, 'a')); //array(0) { }
marianbucur17 at yahoo dot com ¶
8 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;
}, []);
}
}
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;
}
robbieaverill[at]gmail.com ¶
9 years ago
Another option for older PHP versions (pre 5.5.0) is to use array_walk():
<?php
$array = array(
array('some' => 'var', 'foo' => 'bar'),
array('some' => 'var', 'foo' => 'bar'),
array('some' => 'var', 'foo' => 'bar')
);
array_walk($array, function(&$value, $key, $return) {
$value = $value[$return];
}, 'foo');
print_r($array);
// Array
// (
// [0] => bar
// [1] => bar
// [2] => bar
// )
?>
myles at smyl dot es ¶
9 years ago
This didn't work for me recursively and needed to come up with a solution.
Here's my solution to the function:
if ( ! function_exists( 'array_column_recursive' ) ) {
/**
* Returns the values recursively from columns of the input array, identified by
* the $columnKey.
*
* Optionally, you may provide an $indexKey to index the values in the returned
* array by the values from the $indexKey column in the input array.
*
* @param array $input A multi-dimensional array (record set) 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.
* @param mixed $indexKey (Optional.) 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_recursive( $input = NULL, $columnKey = NULL, $indexKey = NULL ) {
// Using func_get_args() in order to check for proper number of
// parameters and trigger errors exactly as the built-in array_column()
// does in PHP 5.5.
$argc = func_num_args();
$params = func_get_args();
if ( $argc < 2 ) {
trigger_error( "array_column_recursive() expects at least 2 parameters, {$argc} given", E_USER_WARNING );
return NULL;
}
if ( ! is_array( $params[ 0 ] ) ) {
// Because we call back to this function, check if call was made by self to
// prevent debug/error output for recursiveness :)
$callers = debug_backtrace();
if ( $callers[ 1 ][ 'function' ] != 'array_column_recursive' ){
trigger_error( 'array_column_recursive() expects parameter 1 to be array, ' . gettype( $params[ 0 ] ) . ' given', E_USER_WARNING );
}
return NULL;
}
if ( ! is_int( $params[ 1 ] )
&& ! is_float( $params[ 1 ] )
&& ! is_string( $params[ 1 ] )
&& $params[ 1 ] !== NULL
&& ! ( is_object( $params[ 1 ] ) && method_exists( $params[ 1 ], '__toString' ) )
) {
trigger_error( 'array_column_recursive(): The column key should be either a string or an integer', E_USER_WARNING );
return FALSE;
}
if ( isset( $params[ 2 ] )
&& ! is_int( $params[ 2 ] )
&& ! is_float( $params[ 2 ] )
&& ! is_string( $params[ 2 ] )
&& ! ( is_object( $params[ 2 ] ) && method_exists( $params[ 2 ], '__toString' ) )
) {
trigger_error( 'array_column_recursive(): The index key should be either a string or an integer', E_USER_WARNING );
return FALSE;
}
$paramsInput = $params[ 0 ];
$paramsColumnKey = ( $params[ 1 ] !== NULL ) ? (string) $params[ 1 ] : NULL;
$paramsIndexKey = NULL;
if ( isset( $params[ 2 ] ) ) {
if ( is_float( $params[ 2 ] ) || is_int( $params[ 2 ] ) ) {
$paramsIndexKey = (int) $params[ 2 ];
} else {
$paramsIndexKey = (string) $params[ 2 ];
}
}
$resultArray = array();
foreach ( $paramsInput as $row ) {
$key = $value = NULL;
$keySet = $valueSet = FALSE;
if ( $paramsIndexKey !== NULL && array_key_exists( $paramsIndexKey, $row ) ) {
$keySet = TRUE;
$key = (string) $row[ $paramsIndexKey ];
}
if ( $paramsColumnKey === NULL ) {
$valueSet = TRUE;
$value = $row;
} elseif ( is_array( $row ) && array_key_exists( $paramsColumnKey, $row ) ) {
$valueSet = TRUE;
$value = $row[ $paramsColumnKey ];
}
$possibleValue = array_column_recursive( $row, $paramsColumnKey, $paramsIndexKey );
if ( $possibleValue ) {
$resultArray = array_merge( $possibleValue, $resultArray );
}
if ( $valueSet ) {
if ( $keySet ) {
$resultArray[ $key ] = $value;
} else {
$resultArray[ ] = $value;
}
}
}
return $resultArray;
}
}
coviex ¶
9 years ago
Value for existing key in the resulting array is rewritten with new value if it exists in another source sub-array.
robsonvnasc at gmail dot com ¶
6 years ago
Retrieve multiple columns from an array:
$columns_wanted = array('foo','bar');
$array = array('foo'=>1,'bar'=>2,'foobar'=>3);
$filtered_array = array_intersect_key(array_fill_keys($columns_wanted,''));
//filtered_array
// array('foo'=>1,'bar'=>2);
Dominik59 ¶
6 years ago
Presented function is good when You want to flatten nested array base on only one column, but if You want to flatten whole array You can use this method:
/**
* Method that transforms nested array into the flat one in below showed way:
* [
* [
* [0]=>'today',
* ],
* [
* [0]=>'is',
* [1]=>'very',
* [2]=> [
* [0]=>'warm'
* ],
* ],
* ]
*
* Into:
*
* ['today','is','very','warm']
*
* @param $input
* @return array
*/
private function transformNestedArrayToFlatArray($input)
{
$output_array = [];
if (is_array($input)) {
foreach ($input as $value) {
if (is_array($value)) {
$output_array = array_merge($output_array, $this->transformNestedArrayToFlatArray($value));
} else {
array_push($output_array, $value);
}
}
} else {
array_push($output_array, $input);
}
return $output_array;
}
greensea ¶
7 years ago
<?php
if (!function_exists('array_column')) {
function array_column($input, $column_key, $index_key = NULL) {
if (!is_array($input)) {
trigger_error(__FUNCTION__ . '() expects parameter 1 to be array, ' . gettype($input) . ' given', E_USER_WARNING);
return FALSE;
}
$ret = array();
foreach ($input as $k => $v) {
$value = NULL;
if ($column_key === NULL) {
$value = $v;
}
else {
$value = $v[$column_key];
}
if ($index_key === NULL || !isset($v[$index_key])) {
$ret[] = $value;
}
else {
$ret[$v[$index_key]] = $value;
}
}
return $ret;
}
}
?>
