(PHP 5, PHP 7, PHP 8)
array_combine — Creates an array by using one array for keys and another for its values
Parameterskeys
Array of keys to be used. Illegal values for key will be converted to string.
values
Array of values to be used
Returns the combined array.
Errors/ExceptionsAs of PHP 8.0.0, a ValueError is thrown if the number of elements in keys and values does not match. Prior to PHP 8.0.0, a E_WARNING was emitted instead.
false instead. Examples
Example #1 A simple array_combine() example
<?php
$a = array('green', 'red', 'yellow');
$b = array('avocado', 'apple', 'banana');
$c = array_combine($a, $b);print_r($c);
?>
The above example will output:
Array
(
[green] => avocado
[red] => apple
[yellow] => banana
) loureirorg at gmail dot com ¶
12 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
)
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 $result;
}print_r(array_combine_(Array('a','a','b'), Array(1,2,3)));
?>
Returns:
Array
(
[a] => Array
(
[0] => 1
[1] => 2
)
[b] => 3
) welcome at el hyphen mustafa ¶
9 years ago
Further to loreiorg's script
in order to preserve duplicate keys when combining arrays.
I have modified the script to use a closure instead of create_function
Reason: see security issue flagged up in the documentation concerning create_function
<?phpfunction array_combine_($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
$result;
}?>
claude dot pache at gmail dot com ¶
15 years ago
array_combine() has a strange bug/misfeature (as of PHP 5.3.2): There is no logical reason for <? array_combine(array(), array()) ?> throwing a warning and returning FALSE, instead of returning <? array() ?> (see http://bugs.php.net/bug.php?id=34857). Here is a quick workaround:
<?php
function array_real_combine($a, $b)
{
return $a===array() && $b===array() ? array() : array_combine($a, $b);
}
?> quecoder at gmail ¶
16 years ago
<?php
$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); ?> dejiakala at gmail dot com ¶
13 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 $b is an array of the current row retrieved with fgetcsv()
<?phpfunction array_combine_special($a, $b, $pad = TRUE) {
$acount = count($a);
$bcount = count($b);
if (!$pad) {
$size = ($acount > $bcount) ? $bcount : $acount;
$a = array_slice($a, 0, $size);
$b = array_slice($b, 0, $size);
} else {
if ($acount > $bcount) {
$more = $acount - $bcount;
$more = $acount - $bcount;
for($i = 0; $i < $more; $i++) {
$b[] = "";
}
} else if ($acount < $bcount) {
$more = $bcount - $acount;
for($i = 0; $i < $more; $i++) {
$key = 'extra_field_0' . $i;
$a[] = $key;
}
}
}
return
array_combine($a, $b);
}
?>
zequez at gmail dot com ¶
14 years ago
If two keys are the same, the second one prevails.
Example:
<?php
print_r(array_combine(Array('a','a','b'), Array(1,2,3)));
?>
Returns:
Array
(
[a] => 2
[b] => 3
)
15 years ago
I needed a function that would take keys from one unequal array and combine them with the values of another. Real life application:
Select 4 product types.
Each product has a serial.
There are 4 sets of products.
<?php
function array_combine2($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 ¶
8 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.
ilanfir at gmail dot com ¶
10 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
)
) g.REMOVETHIS.vincendon AT vithemis.com ¶
13 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);$check = count(array_unique(array_map('is_array',array_map('current',$arrays)))) === 1;
if (!$check) { trigger_error('Function array_combine_array() expects all parameters to be same type array or array of array',E_USER_NOTICE); return array(); }$assocArray = is_array(array_shift(array_map('current',$arrays)));if (empty($keys)) $keys = array_keys(array_fill(0,max(($assocArray) ? array_map('count',array_map('current',$arrays)) : array_map('count',$arrays)),'foo'));$ret=array();$i=0;
foreach($keys as $v)
{
foreach ($arrays as $k)
{
if ($assocArray)
{
$key = key($k);
$ret[$v][$key] = isset($k[$key][$i]) ? $k[$key][$i]:false;
}
else
$ret[$v][] = isset($k[$i]) ? $k[$i]: false;
}
$i++;
}
return $ret;
}$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' => $a3))); print_r(array_combine_array($r,$a1,array('french' => $a2),array('spanish' => $a3))); print_r(array_combine_array($r,$a1,$a2,$a3)); print_r(array_combine_array(array(),array('english' => $a1),array('french' => $a2),array('spanish' => $a3))); ?>
Dan LaManna ¶
13 years ago
I needed a function that truncated extra values, and only went as far as keys without throwing a warning as array_combine does.
<?php
function safeArrayCombine($keys, $values) {
$combinedArray = array();
for (
$i=0, $keyCount = count($keys); $i < $keyCount; $i++) {
$combinedArray[$keys[$i]] = $values[$i];
}
return
$combinedArray;
}
?>
douglasrich9215 at gmail dot com ¶
7 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)));
info at callismart dot com dot ng ¶
1 year ago
As of PHP 8.0, array_combine throws ValueError if the number of elements for each array is not equal;
To be on a safer side, you can perform a check instead.
$arrayk = array( 'key1', 'key2', 'key3' );
$arrayv = array( 'v1', 'v2', 'v3' );
if ( count( $arrayk ) === count( $arrayv ) ) {
echo '<pre>';
var_dump( array_combine( $arrayk, $arrayv ) );
echo '</pre>';
} else {
return false;
}
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