If two keys are the same, the second one prevails.
Example:
<?php
print_r(array_combine(Array('a','a','b'), Array(1,2,3)));
?>
Returns:
Array
(
[a] => 2
[b] => 3
)
But if you need to keep all values, you can use the function below:
<?php
function array_combine_($keys, $values)
{
$result = array();
foreach ($keys as $i => $k) {
$result[$k][] = $values[$i];
}
array_walk($result, create_function('&$v', '$v = (count($v) == 1)? array_pop($v): $v;'));
return $result;
}
print_r(array_combine_(Array('a','a','b'), Array(1,2,3)));
?>
Returns:
Array
(
[a] => Array
(
[0] => 1
[1] => 2
)
[b] => 3
)
PHP - Manual: array_combine
2024-12-22
array_combine
(PHP 5, PHP 7, PHP 8)
array_combine — 创建一个数组，用一个数组的值作为其键名，另一个数组的值作为其值
说明
array_combine(array
$keys, array $values): array
返回一个 array，用来自
keys 数组的值作为键名，来自
values 数组的值作为相应的值。
参数
-
keys -
将被作为新数组的键。非法的值将会被转换为字符串类型（string）。
-
values -
将被作为 Array 的值。
返回值
返回合并的 array，如果两个数组的单元数不同则返回 false。
错误／异常
如果作为keys的数组和作为values的数组的元素个数不一样，将会抛出一个警告错误（E_WARNING）。
范例
示例 #1 一个 array_combine() 简单的例子
<?php
$a = array('green', 'red', 'yellow');
$b = array('avocado', 'apple', 'banana');
$c = array_combine($a, $b);
print_r($c);
?>
以上例程会输出：
Array
(
[green] => avocado
[red] => apple
[yellow] => banana
)
add a note
User Contributed Notes 22 notes
loureirorg at gmail dot com ¶
9 years ago
welcome at el hyphen mustafa ¶
6 years ago
Further to loreiorg's script
in order to preserve duplicate keys when combining arrays.
I have modified the script to use a closure instead of create_function
Reason: see security issue flagged up in the documentation concerning create_function
<?php
function array_combine_($keys, $values){
$result = array();
foreach ($keys as $i => $k) {
$result[$k][] = $values[$i];
}
array_walk($result, function(&$v){
$v = (count($v) == 1) ? array_pop($v): $v;
});
return $result;
}
?>
claude dot pache at gmail dot com ¶
12 years ago
array_combine() has a strange bug/misfeature (as of PHP 5.3.2): There is no logical reason for <? array_combine(array(), array()) ?> throwing a warning and returning FALSE, instead of returning <? array() ?> (see http://bugs.php.net/bug.php?id=34857). Here is a quick workaround:
<?php
function array_real_combine($a, $b)
{
return $a===array() && $b===array() ? array() : array_combine($a, $b);
}
?>
quecoder at gmail ¶
13 years ago
<?php
// If they are not of same size, here is solution:
$abbreviations = array("AL", "AK", "AZ", "AR", "TX", "CA");
$states = array("Alabama", "Alaska", "Arizona", "Arkansas");
function combine_arr($a, $b)
{
$acount = count($a);
$bcount = count($b);
$size = ($acount > $bcount) ? $bcount : $acount;
$a = array_slice($a, 0, $size);
$b = array_slice($b, 0, $size);
return array_combine($a, $b);
}
$combined = combine_arr($abbreviations, $states);
print_r($combined);
// Output
// Array ( [AL] => Alabama [AK] => Alaska [AZ] => Arizona
// [AR] => Arkansas )
?>
zequez at gmail dot com ¶
11 years ago
If two keys are the same, the second one prevails.
Example:
<?php
print_r(array_combine(Array('a','a','b'), Array(1,2,3)));
?>
Returns:
Array
(
[a] => 2
[b] => 3
)
g.REMOVETHIS.vincendon AT vithemis.com ¶
9 years ago
I was looking for a function that could combine an array to multiple one, for my MySQL GROUP_CONCAT() query, so I made this function.
<?php
function array_combine_array(array $keys)
{
$arrays = func_get_args();
$keys = array_shift($arrays);
/* Checking if arrays are on the same model (array('INDEX'=> array()) or array()) */
$check = count(array_unique(array_map('is_array',array_map('current',$arrays)))) === 1;
if (!$check) { trigger_error('Function array_combine_array() expects all parameters to be same type array or array of array',E_USER_NOTICE); return array(); }
/* Checking the model of arrays, array('INDEX' => array()) or Array() */
$assocArray = is_array(array_shift(array_map('current',$arrays)));
/* If empty $Keys is given, we fill an empty array */
if (empty($keys)) $keys = array_keys(array_fill(0,max(($assocArray) ? array_map('count',array_map('current',$arrays)) : array_map('count',$arrays)),'foo'));
/* Init */
$ret=array();$i=0;
/* Cycling on each keys values, making an offset for each */
foreach($keys as $v)
{
/* Cycling on arrays */
foreach ($arrays as $k)
{
if ($assocArray)
{
/* Getting the index of the element */
$key = key($k);
/* If the offset exists, we place it */
$ret[$v][$key] = isset($k[$key][$i]) ? $k[$key][$i]:false;
}
/* Making the array with auto-made index */
else
$ret[$v][] = isset($k[$i]) ? $k[$i]: false;
}
/* Getting the next offset */
$i++;
}
return $ret;
}
/* Examples */
$r = array(1,2,4,10);
$a1 = array('one','two','four','ten');
$a2 = array('un','deux','quatre','dix');
$a3 = array('uno','dos','quatro','diez');
print_r(array_combine_array($r,array('english' => $a1),array('french' => $a2),array('spanish' => $a3))); /* Associative index, associative subarray indexes */
print_r(array_combine_array($r,$a1,array('french' => $a2),array('spanish' => $a3))); /* Ouputs Error */
print_r(array_combine_array($r,$a1,$a2,$a3)); /* Associative index, auto-made subarray indexes */
print_r(array_combine_array(array(),array('english' => $a1),array('french' => $a2),array('spanish' => $a3))); /* Auto-made index, associative subarray indexes */
?>
dejiakala at gmail dot com ¶
10 years ago
I needed to read CSV files into associative arrays with column headers as keys. Then I ran into a problem when you have empty columns at the end of a row because array_combine returns false if both arrays don't have the same number of elements. This function based on quecoder at gmail's combine_arr() below allowed me to pad either array or not when parsing my CSVs to arrays.
$a is the array of header columns and $b is an array of the current row retrieved with fgetcsv()
<?php
function array_combine_special($a, $b, $pad = TRUE) {
$acount = count($a);
$bcount = count($b);
// more elements in $a than $b but we don't want to pad either
if (!$pad) {
$size = ($acount > $bcount) ? $bcount : $acount;
$a = array_slice($a, 0, $size);
$b = array_slice($b, 0, $size);
} else {
// more headers than row fields
if ($acount > $bcount) {
$more = $acount - $bcount;
// how many fields are we missing at the end of the second array?
// Add empty strings to ensure arrays $a and $b have same number of elements
$more = $acount - $bcount;
for($i = 0; $i < $more; $i++) {
$b[] = "";
}
// more fields than headers
} else if ($acount < $bcount) {
$more = $bcount - $acount;
// fewer elements in the first array, add extra keys
for($i = 0; $i < $more; $i++) {
$key = 'extra_field_0' . $i;
$a[] = $key;
}
}
}
return array_combine($a, $b);
}
?>
ilanfir at gmail dot com ¶
7 years ago
I recently had to flip an array and group the elements by value, this snippet will do that:
<?php
function flipAndGroup($input) {
$outArr = array();
array_walk($input, function($value, $key) use (&$outArr) {
if(!isset($outArr[$value]) || !is_array($outArr[$value])) {
$outArr[$value] = [];
}
$outArr[$value][] = $key;
});
return $outArr;
}
?>
Example:
<?php
$users_countries = array(
'username1' => 'US',
'user2' => 'US',
'newuser' => 'GB'
);
print_r(flipAndGroup($users_countries));
?>
Returns:
Array
(
[US] => Array
(
[0] => username1
[1] => user2
)
[GB] => Array
(
[0] => newuser
)
)
bradentkeith at dot dontspam dot gmail dot com ¶
12 years ago
I needed a function that would take keys from one unequal array and combine them with the values of another. Real life application:
Select 4 product types.
Each product has a serial.
There are 4 sets of products.
<?php
function array_combine2($arr1, $arr2) {
$count1 = count($arr1);
$count2 = count($arr2);
$numofloops = $count2/$count1;
$i = 0;
while($i < $numofloops){
$arr3 = array_slice($arr2, $count1*$i, $count1);
$arr4[] = array_combine($arr1,$arr3);
$i++;
}
return $arr4;
}
?>
Input:
Array
(
[0] => SMART Board
[1] => Projector
[2] => Speakers
[3] => Splitter
)
, Array
(
[0] => serial to smart board1
[1] => serial to projector 1
[2] => serial to speakers 1
[3] => serials to splitter 1
[4] => serials to smart board 2
[5] => serials to projector 2
[6] => serials to speakers 2
[7] => serials to splitter 2
)
Array
(
[0] => Array
(
[SMART Board] => serial to smart board1
[Projector] => serial to projector 1
[Speakers] => serial to speakers 1
[Splitter] => serials to splitter 1
)
[1] => Array
(
[SMART Board] => serials to smart board 2
[Projector] => serials to projector 2
[Speakers] => serials to speakers 2
[Splitter] => serials to splitter 2
)
)
PHPNewbie ¶
4 years ago
This will seem obvious to some, but if you need to preserve a duplicate key, being you have unique vars, you can switch the array_combine around, to where the vars are the keys, and this will output correctly.
This [default] formula auto-removes the duplicate keys.
$i=0;
foreach (array_combine($keys, $vars) as $key => $var)
{
$i=$i;
echo($key);
echo " ";
echo($var);
}
This formula accomplishes the same thing, in the same order, but the duplicate "keys" (which are now vars) are kept.
$i=0;
foreach (array_combine($vars, $keys) as $var => $key)
{
$i=$i;
echo($key);
echo " ";
echo($var);
}
I know, I'm a newbie, but perhaps someone else will need this eventually. I couldn't find another solution anywhere.
Dan LaManna ¶
10 years ago
I needed a function that truncated extra values, and only went as far as keys without throwing a warning as array_combine does.
<?php
function safeArrayCombine($keys, $values) {
$combinedArray = array();
for ($i=0, $keyCount = count($keys); $i < $keyCount; $i++) {
$combinedArray[$keys[$i]] = $values[$i];
}
return $combinedArray;
}
?>
Khaly ¶
14 years ago
This is the function for PHP4 :
<?php
function array_combine($arr1,$arr2) {
$out = array();
foreach($arr1 as $key1 => $value1) {
$out[$value1] = $arr2[$key1];
}
return $out
}
?>
Mike Jean ¶
14 years ago
Khaly's PHP4 code below does not work correctly in all cases. Consider when your array consists of floats:
<?php
$okay = array(0, 10, 20, 30);
$not_okay = array(0, 0.5, 1, 1.5);
$foo = array_combine($okay, $okay);
$bar = array_combine($not_okay, $not_okay);
/*
Results:
$foo = {
[0]=> int(0)
[10]=> int(10)
[20]=> int(20)
[30]=> int(30)
}
$bar = {
[0]=> float(0.5)
[1]=> float(1.5)
}
*/
?>
What can you do? In my case, I was just zipping up some select-box options, so I converted everything in my floats to strings.
Anonymous ¶
5 months ago
Here a way to manage no uniqueness keys case. Values of duplicate keys are put in an array.
<?php
function array_combine_multi(array $keys, array $values)
{
if (count($keys) !== count($values)) {
throw new Exception('Arrays count mismatch');
}
$result = [];
foreach ($values as $i => $value) {
if (!isset($result[$keys[$i]])) {
$result[$keys[$i]] = $value;
} elseif (!is_array($result[$keys[$i]])) {
$result[$keys[$i]] = [$result[$keys[$i]], $value];
} else {
$result[$keys[$i]][] = $value;
}
}
return $result;
}
$keys = ['key-1', 'key-2', 'key-3', 'key-2', 'key-2'];
$values = ['value-1', 'value-2', 'value-3', 'value-4', 'value-5'];
$result = array_combine_multi($keys, $values);
print_r($result);
/*
Gives :
Array (
[key-1] => value-1
[key-2] => Array (
[0] => value-2
[1] => value-4
[2] => value-5
)
[key-3] => value-3
)
*/
douglasrich9215 at gmail dot com ¶
4 years ago
I had an epiphany when try to handle NON-ASSOCIATIVE array forms in my controller. This little one liner can pretty much edit ANY kind of non-associative array. For example this one just returns an array of values inputed by a new user.
The $data value is the the json_decoded() value of a register form.
Here is used str_replace, you could definitely do a number of things like preg matches and other things.
$readyToProcessForUser = array_combine(str_replace("new_user_", "", array_keys($data)), $data);
You could also do the same for the values.
$readyToProcessForUser = array_combine(array_keys($data), str_replace("-", "", $data));
Or BOTH!
Use full if you don't want to walk an entire array and the keys through the same callback.
$readyToProcessForUser = array_combine(array_walk('trim', array_keys($data)), array_walk('custom_callback', array_values($data)));
elite1228 at 163 dot com ¶
6 years ago
$item = array();
array_map(
function($element) use($column_name,$key,&$item){
$item[$element[$key]] = $element[$column_name];
},
$data
);
neoyahuu at yahoo dot com ¶
15 years ago
Some tips for merging same values in an array
<?php
$array1 = array(1,2,3,4,5,6,7,8,9,10,11,12);
$array2 = array(1,2,3,13);
$merged = array_merge($array1,$array2);
// output normal array_merge
echo '<pre>After array_merge :
';
print_r($merged);
echo '</pre>';
// do double flip for merging values in an array
$merged = array_flip($merged);
$merged = array_flip($merged);
// Output after
echo '<pre>After Double Flip :
';
print_r($merged);
echo '</pre>';
?>
Output ::
After array_merge :
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
[5] => 6
[6] => 7
[7] => 8
[8] => 9
[9] => 10
[10] => 11
[11] => 12
[12] => 1
[13] => 2
[14] => 3
[15] => 13
)
After Double Flip :
Array
(
[12] => 1
[13] => 2
[14] => 3
[3] => 4
[4] => 5
[5] => 6
[6] => 7
[7] => 8
[8] => 9
[9] => 10
[10] => 11
[11] => 12
[15] => 13
)
ismorodin at hotmail dot com ¶
8 years ago
Function eliminates the error Throws E_WARNING if the number of elements in keys and values does not match.
function arrCombine($arr1 = array(),$arr2 = array()){
if(is_array($arr1) && is_array($arr2)):
$cntArr1 = count($arr1);
$cntArr2 = count($arr2);
$difference = max($cntArr1,$cntArr2) - min($cntArr1,$cntArr2);
if($cntArr1 > $cntArr2):
for ($i=1;$i<=$difference;$i++){
$arr2[$cntArr2+$i] = $cntArr2 + 1;
}
return array_combine($arr1,$arr2);
elseif($cntArr1 < $cntArr2):
for ($i=1;$i<=$difference;$i++){
$arr1[$cntArr1+$i] = count($arr1) + 1;
}
return array_combine($arr1,$arr2);
else:
return array_combine($arr1,$arr2);
endif;
endif;
}
$array = [1,4,5,6,7,8];
$array2 = ['john','smith'];
var_dump( arrCombine($array,$array2 ));
array (size=6)
1 => string 'john' (length=4)
4 => string 'smith' (length=5)
5 => int 3
6 => int 3
7 => int 3
8 => int 3
var_dump( arrCombine($array2,$array) );
array (size=6)
'john' => int 1
'smith' => int 4
3 => int 5
4 => int 6
5 => int 7
6 => int 8
J.D.D. ¶
13 years ago
This may be obvious, but I don't see anything about it on the manual page, so a friendly warning... The array you are using as keys must have all unique values. If not, array elements get dropped.
<?php
$arr_notUnique = array('one' , 'one' , 'two');
$arr_b = array('red' , 'green' , 'blue');
$arr_combo = array_combine($arr_notUnique, $arr_b);
?>
Results: Array ( [one] => green [two] => blue )
NOT: Array ( [one] => red [one] => green [two] => blue )
xavier at api-meal dot eu ¶
12 years ago
<?php
/**
* Return alternatives defined by values of each parameters.
*
* Exemple :
*
* array_alternatives(array('foo','bar'), array('baz', 'qux'));
* array(
* array('foo', 'baz'),
* array('bar', 'baz'),
* array('foo', 'qux'),
* array('bar', 'qux'),
* );
*
* array_alternatives(array('a'), array('simple-minded'), array('solution'));
* array(
* array('a', 'simple-minded', 'solution')
* );
*
* array_alternatives(array('a'), array('red', 'blue'), array('car'));
* array(
* array('a', 'red', 'car'),
* array('a', 'blue', 'car'),
* );
*
* @param array $first_element
* @param array $second_element
* @return array
* @author Xavier Barbosa
*/
function array_alternatives(array $first_element, array $second_element)
{
$lists = func_get_args();
$total_lists = func_num_args();
for($i=0; $i<$total_lists; $i++)
{
$list =& $lists[$i];
if (is_array($list) === FALSE)
throw new Exception("Parameter $i is not an array.");
if (count($list) === 0)
throw new Exception("Parameter $i has no element.");
unset($list);
}
// Initialize our alternatives
$alternatives = array();
foreach($lists[0] as &$value)
{
array_push($alternatives, array($value));
unset($value);
}
unset($lists[0]);
// Process alternatives
for($i=1; $i<$total_lists; $i++)
{
$list =& $lists[$i];
$new_alternatives = array();
foreach($list as &$value)
{
foreach($alternatives as $_)
{
array_push($_, $value);
array_push($new_alternatives, $_);
}
}
// Rotate references, it's cheaper than copy array like `$alternatives = $new_alternatives;`
$alternatives =& $new_alternatives;
unset($new_alternatives, $list, $lists[$i]);
}
return $alternatives;
}
?>
aaron at aaronholmes dot net ¶
9 years ago
You can create an array hashset from a flat array, storing both keys and values, with array_combine(). This works with duplicate values in the array too.
<?php
$flat_array = array(
'one',
'two',
'three',
'three',
'four',
'one'
);
$set = array_combine($flat_array, $flat_array);
var_dump($set);
?>
This outputs the following:
array(4) {
["one"]=>
string(3) "one"
["two"]=>
string(3) "two"
["three"]=>
string(5) "three"
["four"]=>
string(4) "four"
}
info at maisuma dot jp ¶
7 years ago
array_combine() returns NULL instrad of FALSE, when non-array parameters are given (issuing warning).
<?php
//NULL
var_dump(array_combine('string',array(42)));
?>
官方地址：https://www.php.net/manual/en/function.array-combine.php
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