PHP 7.2.0 Beta 3 Released

array_column

(PHP 5 >= 5.5.0, PHP 7)

array_column返回数组中指定的一列

说明

array array_column ( array $input , mixed $column_key [, mixed $index_key = null ] )

array_column() 返回input数组中键值为column_key的列, 如果指定了可选参数index_key,那么input数组中的这一列的值将作为返回数组中对应值的键。

参数

input

需要取出数组列的多维数组。 如果提供的是包含一组对象的数组,只有 public 属性会被直接取出。 为了也能取出 private 和 protected 属性,类必须实现 __get()__isset() 魔术方法。

column_key

需要返回值的列,它可以是索引数组的列索引,或者是关联数组的列的键,也可以是属性名。 也可以是NULL,此时将返回整个数组(配合index_key参数来重置数组键的时候,非常管用)

index_key

作为返回数组的索引/键的列,它可以是该列的整数索引,或者字符串键值。

返回值

从多维数组中返回单列数组。

更新日志

版本 说明
7.0.0 input 参数现在可以是包含对象的数组。

范例

Example #1 从结果集中取出first names列

<?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);
?>

以上例程会输出:

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

Example #2 从结果集中总取出last names列,用相应的id作为键值

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

以上例程会输出:

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

Example #3 username 列是从对象获取 public 的 "username" 属性

<?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'));
?>

以上例程会输出:

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

Example #4 获取 username 列,从对象通过魔术方法 __get() 获取 private 的 "username" 属性。

<?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'));
?>

以上例程会输出:

Array
(
    [0] => Fred
    [1] => Jane
    [2] => John
)
如果不提供__isset(),会返回空数组。

add a note add a note

User Contributed Notes 22 notes

up
68
mohanrajnr at gmail dot com
2 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
51
WARrior
3 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);
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5
nino at recgr dot com
10 months 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
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14
till at etill dot net
2 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
5
kaspar dot wilbuer at web dot de
1 year 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
6
Anonymous
1 year 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;
    }
}
?>
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1
Carlos Granados
10 months 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']
]

?>
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2
antonfedonjuk at gmail dot com
2 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
$result;
    }
}
?>
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1
1184427175 at qq dot com
1 month ago
//php < 5.5
if(function_exists('array_column'))
{
    function array_column($arr_data, $col)
    {
        $result = array_map(function($arr){return $arr[$col]}, $arr_data);
        return $result;
    }
}
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0
Dominik59
6 days 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;
    }
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0
katrinaelaine6 at gmail dot com
5 months 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
)

*/

?>
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-1
robsonvnasc at gmail dot com
13 days 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);
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0
miguelfzarth at gmail dot com
1 year 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;
    }
}
?>
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0
benjam
1 year 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)

*/
?>
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0
Nolan chou
1 year 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 $result;
    }
}
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-2
greensea
1 year ago
<?php
if (!function_exists('array_column')) {
    function
array_column($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;
    }
}
?>
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-3
marianbucur17 at yahoo dot com
2 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;
        }, []);
    }
}
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-4
hypxm at qq dot com
2 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;
    }
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-6
kiler129 @ nowhere
2 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) { }
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-6
robbieaverill[at]gmail.com
2 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
// )

?>
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-10
coviex
2 years ago
Value for existing key in the resulting array is rewritten with new value if it exists in another source sub-array.
up
-14
myles at smyl dot es
2 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;
    }
}
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