array_keys
@ erik dot stetina at gmail dot com 27-Sep-2011 03:05;
<?php
function array_prefix_values($prefix, $array) {
return array_map(function($str) use($prefix) {
return $prefix . $str;
}, $array);
}
?>
array_map
(PHP 4 >= 4.0.6, PHP 5)
array_map — Applies the callback to the elements of the given arrays
Description
array_map() returns an array containing all
the elements of arr1 after applying the
callback function to each one.
The number of parameters that the callback
function accepts
should match the number of arrays
passed to the array_map()
Parameters
-
callback -
Callback function to run for each element in each array.
-
arr1 -
An array to run through the
callbackfunction. -
array -
Variable list of array arguments to run through the
callbackfunction.
Return Values
Returns an array containing all the elements of arr1
after applying the callback function to each one.
Examples
Example #1 array_map() example
<?php
function cube($n)
{
return($n * $n * $n);
}
$a = array(1, 2, 3, 4, 5);
$b = array_map("cube", $a);
print_r($b);
?>
This makes $b have:
Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)
Example #2 array_map() using a lambda function (as of PHP 5.3.0)
<?php
$func = function($value) {
return $value * 2;
};
print_r(array_map($func, range(1, 5)));
?>
Array
(
[0] => 2
[1] => 4
[2] => 6
[3] => 8
[4] => 10
)
Example #3 array_map() - using more arrays
<?php
function show_Spanish($n, $m)
{
return("The number $n is called $m in Spanish");
}
function map_Spanish($n, $m)
{
return(array($n => $m));
}
$a = array(1, 2, 3, 4, 5);
$b = array("uno", "dos", "tres", "cuatro", "cinco");
$c = array_map("show_Spanish", $a, $b);
print_r($c);
$d = array_map("map_Spanish", $a , $b);
print_r($d);
?>
The above example will output:
// printout of $c
Array
(
[0] => The number 1 is called uno in Spanish
[1] => The number 2 is called dos in Spanish
[2] => The number 3 is called tres in Spanish
[3] => The number 4 is called cuatro in Spanish
[4] => The number 5 is called cinco in Spanish
)
// printout of $d
Array
(
[0] => Array
(
[1] => uno
)
[1] => Array
(
[2] => dos
)
[2] => Array
(
[3] => tres
)
[3] => Array
(
[4] => cuatro
)
[4] => Array
(
[5] => cinco
)
)
Usually when using two or more arrays, they should be of equal length because the callback function is applied in parallel to the corresponding elements. If the arrays are of unequal length, the shortest one will be extended with empty elements.
An interesting use of this function is to construct an array of arrays,
which can be easily performed by using NULL
as the name of the callback function
Example #4 Creating an array of arrays
<?php
$a = array(1, 2, 3, 4, 5);
$b = array("one", "two", "three", "four", "five");
$c = array("uno", "dos", "tres", "cuatro", "cinco");
$d = array_map(null, $a, $b, $c);
print_r($d);
?>
The above example will output:
Array
(
[0] => Array
(
[0] => 1
[1] => one
[2] => uno
)
[1] => Array
(
[0] => 2
[1] => two
[2] => dos
)
[2] => Array
(
[0] => 3
[1] => three
[2] => tres
)
[3] => Array
(
[0] => 4
[1] => four
[2] => cuatro
)
[4] => Array
(
[0] => 5
[1] => five
[2] => cinco
)
)
If the array argument contains string keys then the returned array will contain string keys if and only if exactly one array is passed. If more than one argument is passed then the returned array always has integer keys.
Example #5 array_map() - with string keys
<?php
$arr = array("stringkey" => "value");
function cb1($a) {
return array ($a);
}
function cb2($a, $b) {
return array ($a, $b);
}
var_dump(array_map("cb1", $arr));
var_dump(array_map("cb2", $arr, $arr));
var_dump(array_map(null, $arr));
var_dump(array_map(null, $arr, $arr));
?>
The above example will output:
array(1) {
["stringkey"]=>
array(1) {
[0]=>
string(5) "value"
}
}
array(1) {
[0]=>
array(2) {
[0]=>
string(5) "value"
[1]=>
string(5) "value"
}
}
array(1) {
["stringkey"]=>
string(5) "value"
}
array(1) {
[0]=>
array(2) {
[0]=>
string(5) "value"
[1]=>
string(5) "value"
}
}
See Also
- array_filter() - Filters elements of an array using a callback function
- array_reduce() - Iteratively reduce the array to a single value using a callback function
- array_walk() - Apply a user function to every member of an array
- create_function() - Create an anonymous (lambda-style) function
- information about the callback type
add a note
User Contributed Notes
array_map
qeremy [atta] gmail [dotta] com
02-Mar-2012 11:33
gmail.com@mspreij
26-Feb-2012 10:48
Hope I'm not late to the party, here's my function to apply array_map to the *keys* of an array.
Extra array arguments will be used for the callback function's parameters just like with array_map, with the difference that a string is also allowed: it will just be used to create an array of appropriate length with as each value that string. Arrays are left alone (and will be padded with nulls by array_map as needed).
<?php
//_________________________________________________
// array_map_keys($callback, $array, [$args, ..]) /
function array_map_keys($callback, $array /* [, $args ..] */) {
$args = func_get_args();
if (! is_callable($callback)) trigger_error("first argument (callback) is not a valid function", E_USER_ERROR);
if (! is_array($array)) trigger_error("second argument must be an array", E_USER_ERROR);
$args[1] = array_keys($array);
// If any additional arguments are not arrays, assume that value is wanted for every $array item.
// array_map() will pad shorter arrays with Null values
for ($i=2; $i < count($args); $i++) {
if (! is_array($args[$i])) {
$args[$i] = array_fill(0, count($array), $args[$i]);
}
}
return array_combine(call_user_func_array('array_map', $args), $array);
}
// Some examples:
$arr = array('foo'=>123, 'bar'=>456);
// simply uppercase keys:
var_dump(array_map_keys('strtoupper', $arr));
// or..
var_dump(array_map_keys(function($input) {return strtoupper($input);}, $arr));
// >> array(2) { ["FOO"]=>int(123) , ["BAR"]=> int(456) }
// Add a prefix 'myvar_':
var_dump(array_map_keys(function($input, $prefix) {return $prefix.$input;}, $arr, 'myvar_'));
// >> array(2) { ["myvar_foo"]=>int(123) , ["myvar_bar"]=>int(456) }
// Apart from the (static string) prefix, we also number them:
$arr = array('foo'=>123, 'bar'=>456, 'bazz'=>789, 'yadda'=>'0AB');
var_dump(array_map_keys(function($input, $middle, $number) {return $number.':'.$middle.$input;}, $arr, 'myvar_', range(1, count($arr))));
// >> array(4) { ["1:myvar_foo"]=>int(123) , ["2:myvar_bar"]=>int(456) , ["3:myvar_bazz"]=>int(789) , ["4:myvar_yadda"]=>string(3) "0AB" }
?>
php/hotblocks/nl
28-Nov-2011 05:00
Note that the $arr argument has to be an array, not just a Traversable/Iterator.
For instance this won't work:
<?php
$documents = $mongo->db->collection->find();
// $documents is Traversable by foreach
$ids = array_map(function($document) {
return $document['_id'];
}, $objects);
// $ids will now be NULL, because $documents wasn't an Array
?>
A solution is to first use iterator_to_array():
<?php
$ids = array_map(function($document) {
return $document['_id'];
}, iterator_to_array($objects));
// $ids will now be an array of ['_id']s
?>
But this is not very efficient: two cycles instead of one. Another solution is to use foreach: one cycle and a lot of freedom (and in the same scope).
erik dot stetina at gmail dot com
27-Sep-2011 03:05
function to prefix given string to each element of an array:
<?php
function array_prefix_values($prefix, $array)
{
$callback = create_function('$str','return "'.$prefix.'".$str;');
return array_map($callback,$array);
}
?>
usage:
<?php
$dir = "./css/";
$files = scandir($dir);
$files = array_prefix_values($dir,$files);
print_r($files);
?>
output:
(
[0] => ./css/.
[1] => ./css/..
[2] => ./css/default.css
[4] => ./css/helper.css
[6] => ./css/page_layout.css
)
spark at limao dot com dot br
08-Sep-2011 07:48
it's a usefull way to filter user input through get and post request arrays:
<?php
$get = array_map("addslashes",$_GET);
?>
gordon dot mcvey at ntlworld dot com
28-Jan-2011 05:11
You can use array_map with PHP native functions as well as user functions. This is very handy if you need to sanitize arrays.
<?php
$integers = array_map ('intval', $integers);
$safeStrings = array_map ('mysql_real_escape_string', $unsafeStrings);
?>
pike-php at kw dot nl
11-Jan-2011 06:04
If you're looking for a way to flatten multimaps, look at this:
<?php
$multimap = array(
array("name"=>"value1"),
array("name"=>"value2"),
array("name"=>"value3")
);
$flatmap = array_map("array_pop",$multimap);
print_r($flatmap);
?>
Output:
Array
(
[0] => value1
[1] => value2
[2] => value3
)
brendan DOT caffrey AT me DOT com
10-Jul-2010 03:42
Something that had me confused:
<?php
namespace test;
class Callback
{
static function add($a) { return $a + 1; }
}
$array = array(0, 1, 2);
array_map(array('Callback', 'add'), $array); // will not work, even though you're calling this in the test namespace
array_map(array('test\Callback', 'add'), $array); // will work
?>
virtual dot greg at gmail dot com
05-Mar-2010 03:07
PHP 5.3 enables us to use inline anonymous functions with array_map, cleaning up the syntax slightly.
<?php
$data = array(
array('id' => 1, 'name' => 'Bob', 'position' => 'Clerk'),
array('id' => 2, 'name' => 'Alan', 'position' => 'Manager'),
array('id' => 3, 'name' => 'James', 'position' => 'Director')
);
$names = array_map(
function($person) { return $person['name']; },
$data
);
print_r($names);
?>
This was possible (although not recommended) in prior versions of PHP 5, via create_function().
<?php
$names = array_map(
create_function('$person', 'return $person["name"];'),
$data
);
?>
You're less likely to catch errors in the latter version because the code is passed as string arguments.
These are alternatives to using a foreach:
<?php
$names = array();
foreach ($data as $row) {
$names[] = $row['name'];
}
?>
kelly m
17-Feb-2010 02:28
I realize this function is easy enough to make, but this is a faster version (twice the speed) of [a function] which I find incredibly useful.
<?php
function array_pluck($key, $input) {
if (is_array($key) || !is_array($input)) return array();
$array = array();
foreach($input as $v) {
if(array_key_exists($key, $v)) $array[]=$v[$key];
}
return $array;
}
?>
Usage:
<?php $ids = array_pluck('id', $users); ?>
onassar at gmail dot com
13-Oct-2009 07:06
Fixed a bug with array recursion.
<?php
/**
* arrayMap function. Customized array_map function which preserves keys/associate array indexes. Note that this costs a descent amount more memory (eg. 1.5k per call)
*
* @access public
* @param callback $callback Callback function to run for each element in each array.
* @param mixed $arr1 An array to run through the callback function.
* @param array $array Variable list of array arugments to run through the callback function.
* @return array Array containing all the elements of $arr1 after applying the callback function to each one, recursively, maintain keys.
*/
function arrayMap($callback,$arr1) {
$results = array();
$args = array();
if(func_num_args()>2)
$args = (array) array_shift(array_slice(func_get_args(),2));
foreach($arr1 as $key=>$value) {
$temp = $args;
array_unshift($temp,$value);
if(is_array($value)) {
array_unshift($temp,$callback);
$results[$key] = call_user_func_array(array('self','arrayMap'),$temp);
} else {
$results[$key] = call_user_func_array($callback,$temp);
}
}
return $results;
}
?>
onassar at gmail dot com
11-Oct-2009 03:33
Wrote up my own key preservation function for array mapping. It allows n arguments to be passed, and should be easy enough to follow if you need to make any mods. If you've got any thoughts let me know.
<?php
/**
* arrayMap function. Customized array_map function which preserves keys/associate array indexes.
*
* @access public
* @param callback $callback Callback function to run for each element in each array.
* @param mixed $arr1 An array to run through the callback function.
* @param array $array Variable list of array arugments to run through the callback function.
* @return array Array containing all the elements of $arr1 after applying the callback function to each one, recursively, maintain keys.
*/
function arrayMap($callback,$arr1) {
$results = array();
$args = array();
if(func_num_args()>2)
$args = (array) array_shift(array_slice(func_get_args(),2));
foreach($arr1 as $key=>$value) {
if(is_array($value)) {
array_unshift($args,$value);
array_unshift($args,$callback);
$results[$key] = call_user_func_array(array('self','arrayMap'),$args);
}
else {
array_unshift($args,$value);
$results[$key] = call_user_func_array($callback,$args);
}
}
return $results;
}
?>
macnimble at gmail dot com
10-Sep-2009 12:27
I recently discovered that PHP has no loop-free manner for modifying the keys in an array. I was hoping to use a built-in function to prefix the keys.
Having found no native function to do this, I threw together this monster:
<?php
function array_prefix_keys ()
{
$args = func_get_args();
$prefix = array_shift($args);
$func = create_function('$p,$k','return "$p{$k}";');
foreach ($args AS $key => $array):
$args[$key] = array_combine( array_map( $func
, array_fill(0,count($array),$prefix)
, array_keys($array)
)
, array_values($array)
);
endforeach;
return $args;
}
$array1 = array(
'id' => 1,
'title' => 'about-us',
'author' => 'Bill Brown',
'dated' => '2009-SEP-15'
);
$array2 = array(
'id' => 2,
'title' => 'about-them',
'author' => 'Bill Smith',
'dated' => '2010-SEP-15'
);
echo '<pre>',print_r($array1,1),print_r($array2,1),'</pre>';
$array = array_prefix_keys("content_",$array1,$array2);
$array1 = $array[0];
$array2 = $array[1];
echo '<pre>',print_r($array1,1),print_r($array2,1),'</pre>';
?>
This will produce the following output:
Array
(
[id] => 1
[title] => about-us
[author] => Bill Brown
[dated] => 2009-SEP-15
)
Array
(
[id] => 2
[title] => about-them
[author] => Bill Smith
[dated] => 2010-SEP-15
)
Array
(
[content_id] => 1
[content_title] => about-us
[content_author] => Bill Brown
[content_dated] => 2009-SEP-15
)
Array
(
[content_id] => 2
[content_title] => about-them
[content_author] => Bill Smith
[content_dated] => 2010-SEP-15
)
Hope it helps!
Bill
[EDIT BY danbrown AT php DOT net: The original function and note was removed in favor of this update by the original author. The original note also contained the following descriptive text.]
I recently discovered that PHP has no loop-free manner for modifying the keys in an array. I was hoping to use a built-in function to prefix the keys.
Having found no native function to do this, I threw together this monster.
ethaizone at hotmail dot com
01-Sep-2009 07:34
My English is weak but I want to share my code.
I want to change formation of array but when I use null is callback function in array_map().
It has problem in result so I write new small function for it.
<?php
function array_change_formation($arr=array()) {
$new_arr = array();
foreach($arr as $k => $v)
foreach($v as $k2 => $v2)
$new_arr[$k2][$k] = $v[$k2];
return $new_arr;
}
?>
Input:
Array
(
[Human] => Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
[Pet] => Array
(
[0] => Cat
[1] => Dog
[2] => Rabbit
[3] => Rat
)
)
OutPut:
Array
(
[0] => Array
(
[Human] => 1
[Pet] => Cat
)
[1] => Array
(
[Human] => 2
[Pet] => Dog
)
[2] => Array
(
[Human] => 3
[Pet] => Rabbit
)
[3] => Array
(
[Human] => 4
[Pet] => Rat
)
)
I hope it can useful.
galenjr at gmail dot com
14-Jun-2009 11:19
Another way to array_map htmlentities with a specific quote style is to create a function that does it and map that function
<?php
function map_entities( $str ) {
return htmlentities( $str, ENT_QUOTES );
}
$good_array = array_map ( 'map_entities', $bad_array );
?>
radist-hack at yandex dot ru
01-Nov-2008 01:37
To transpose rectangular two-dimension array, use the following code:
array_unshift($array, null);
$array = call_user_func_array("array_map", $array);
If you need to rotate rectangular two-dimension array on 90 degree, add the following line before or after (depending on the rotation direction you need) the code above:
$array = array_reverse($array);
Here is example:
<?php
$a = array(
array(1, 2, 3),
array(4, 5, 6));
array_unshift($a, null);
$a = call_user_func_array("array_map", $a);
print_r($a);
?>
Output:
Array
(
[0] => Array
(
[0] => 1
[1] => 4
)
[1] => Array
(
[0] => 2
[1] => 5
)
[2] => Array
(
[0] => 3
[1] => 6
)
)
Heero
16-Oct-2008 10:02
You can easily remove all HTML tags from $_GET or $_POST variables using something like this:
<?php
$_POST = array_map('strip_tags', $_POST);
$_GET = array_map('strip_tags', $_GET);
?>
This is useful when you don't want to parse HTML.
stijnleenknegt at gmail dot com
22-Jul-2008 04:17
If you want to pass an argument like ENT_QUOTES to htmlentities, you can do the follow.
<?php
$array = array_map( 'htmlentities' , $array, array_fill(0 , count($array) , ENT_QUOTES) );
?>
The third argument creates an equal sized array of $array filled with the parameter you want to give with your callback function.
GUI
26-Jun-2008 07:48
The following takes an array of objects, and returns the result of calling a member function on each object. So if I have an array of objects that all have a getName() method, calling array_map_objects("getName", $thingies) will return the array filled with the getName() value for each object.
<?php
function array_map_objects($member_function, $array) {
$values = array();
if(is_string($member_function) && is_array($array)) {
$callback = create_function('$e', 'return call_user_func(array($e, "' . $member_function .'"));');
$values = array_map($callback, $array);
}
return $values;
}
?>
BloodElf
27-Apr-2008 06:32
Here is a simple way to highlight the matched words in the search results:
<?php
function highlight($word) {
static $num = 1;
return '<span class="word' . $num++ . '">' . $word . '</span>';
}
$text = "ala bala nica turska panica";
$search = "bala turska";
$words = explode(' ', $search);
echo str_replace($words, array_map("highlight", $words), $text);
moester at gmail dot com
02-Apr-2008 01:21
Wish this was built in. Mimics Ruby and Prototype's array pluck function. Returns specific key/column from an array of objects.
<?php
function array_pluck($key, $array)
{
if (is_array($key) || !is_array($array)) return array();
$funct = create_function('$e', 'return is_array($e) && array_key_exists("'.$key.'",$e) ? $e["'. $key .'"] : null;');
return array_map($funct, $array);
}
// usage:
$a = array(array("id"=>10, "name"=>"joe"), array("id"=>11, "name"=>"bob"));
$ids = array_pluck("id", $a); // == array(10,11)
$names = array_pluck("name", $a); // == array("joe", "bob")
//works on non-keyed arrays also:
$a = array(array(3,4), array(5,6));
$col2 = array_pluck(1,$a); // == array(4,6) (grab 2nd column of data)
?>
chreekat
12-Mar-2008 03:48
I was miffed that array_map didn't have a way to pass values *and* keys to the callback, but then I realized I could do this:
function callback($k, $v) { ... }
array_map( "callback", array_keys($array), $array);
jo at ho dot nl
17-Feb-2008 02:10
Could also use things like...
array_keys(); and array_values(); offcourse...
However it's just an example off recursion via this function..
Which I found pretty handy at times dealing with arrays..
could also use:
<?php
call_user_func(array($this, __FUNCTION), $args);
?>
or
<?php
call_user_fuc_array(array($this, __FUNCTION__), $array);
?>
or
<?php
class{
public function __construct($arg){
if(is_array($arg)){
new self($arg);
}
else{
echo $arg.'<br/>'.PHP_EOL;
}
}
}
?>
Anyway.. plenty off examples..
It was just an idea for others...
avartabedian at webservice dot com dot uy
08-Feb-2008 05:39
loaded67 at hotmail dot com, there is a little error in the add func params values.
Warning: Missing argument 2 for test::add(), called in /tmp/test.php on line 34 and defined in /tmp/test.php on line 6
Array => <br/>
now it runs...
<?php
class test{
//private $container = array();
final public function add($key, $value=NULL){
/* params values fix */
$value = $value==NULL?$key:$value;
/* recursion */
if(is_array($value)){
array_map(array($this, __FUNCTION__), array_keys($value), array_values($value));
}
/* procedural */
else{
echo $key.' => '.$value.'<br/>'.PHP_EOL;
// do stuff...
// if(!isset($this->container[$key])){
// $this->container[$key] = $value;
// }
//else{ // trigger_error() xor throw new Exception?
// echo 'allready exists!<br/>'.PHP_EOL;
//}
}
}
}
//
$array = array (
'one' => 'value1',
'two' => 'value2',
'three' => 'value3'
);
$t = new test;
$t->add($array);
?>
good luck!
loaded67 at hotmail dot com
08-Feb-2008 02:59
this function is really nice for recursion in php!!!
example in a class:
<?php
class test{
//private $container = array();
final public function add($key, $value){
/* recursion */
if(is_array($value)){
array_map(array($this, __FUNCTION__), array_keys($value), array_values($value));
}
/* procedural */
else{
echo $key.' => '.$value.'<br/>'.PHP_EOL;
// do stuff...
// if(!isset($this->container[$key])){
// $this->container[$key] = $value;
// }
//else{ // trigger_error() xor throw new Exception?
// echo 'allready exists!<br/>'.PHP_EOL;
//}
}
}
}
//
$array = array (
'one' => 'value1',
'two' => 'value2',
'three' => 'value3'
);
$t = new test;
$t->add($array);
?>
you could easiely do this without a class too offcourse!
used in php 5.2.5
pmf
22-Jan-2008 07:02
This function behaves exactly like array_map but additionally does not reject non-array arguments. Instead, it transforms them with the array_fill function to a constant valued array of required length according to the other array arguments (if any) and executes the original array_map function.
<?php
function array_map2() {
$args = func_get_args();
$callback = array_shift($args);
$args = array_map(
create_function('$a,$max','return is_array($a)? $a: array_fill(0,$max,$a);'),
$args,array_fill(0,count($args),array_reduce($args,
create_function('$v,$w','return max($v,is_array($w)? count($w): 1);'))));
array_unshift($args,$callback);
return call_user_func_array("array_map",$args);
}
?>
Example:
<?php
$get = "first=value1&second=value2&third=value3";
print_r(array_map2("explode","=",explode("&",$get)));
?>
would print out:
<?php
Array
(
[0] => Array
(
[0] => first
[1] => value1
)
[1] => Array
(
[0] => second
[1] => value2
)
[2] => Array
(
[0] => third
[1] => value3
)
)
?>
/pmf
henrique at webcoder dot com dot br
01-Nov-2007 08:02
Adding method support to function by Andref (multidimensionalArrayMap).
function array_map_r( $func, $arr )
{
$newArr = array();
foreach( $arr as $key => $value )
{
$newArr[ $key ] = ( is_array( $value ) ? array_map_r( $func, $value ) : ( is_array($func) ? call_user_func_array($func, $value) : $func( $value ) ) );
}
return $newArr;
}
array_map_r('function', array());
or
array_map_r(array('class', 'method'), array());
bturchik at iponweb dot net
19-Jul-2007 07:46
Maybe this one will be useful for someone:
function array_map_helper($mapper, $array) {
$mapper = preg_replace('/^return (.*?);$/', '$1', trim($mapper));
$result = array();
if (preg_match('/(\(?)(.*?)\s*=>\s*(.*?)(\)?)$/', $mapper, $matches)) {
list($full_found, $array_open, $left, $right, $array_close) = $matches;
if ($array_open && $array_close) {
$mapper = '$result[] = array' . $full_found . ';';
} else {
$mapper = '$result[' . $left . '] = ' . $right . ';';
}
} else {
$mapper = '$result[] = ' . $mapper . ';';
}
foreach ($array as $key => $value) {
eval($mapper);
}
return $result;
}
should be used like:
$array = array(array('foo' => 11, 'bar' => 22),
array('foo' => 111, 'bar' => 222),
array('foo' => 1111, 'bar' => 2222));
$mapped = array_map_helper('$value["foo"] => $value["bar"]', $array);
var_dump will give
array(3) {
[11]=>
int(22)
[111]=>
int(222)
[1111]=>
int(2222)
}
or
$mapped = array_map_helper('$value["foo"]', $array);
var_dump will give
array(3) {
[0]=>
int(11)
[1]=>
int(111)
[2]=>
int(1111)
}
or
$mapped = array_map_helper('$value["foo"] + $value["bar"] . " at position $key"', $array);
var_dump will give
array(3) {
[0]=>
string(16) "33 at position 0"
[1]=>
string(17) "333 at position 1"
[2]=>
string(18) "3333 at position 2"
}
andref dot dias at pronus dot eng dot br
24-Oct-2006 12:14
A recursive way to handle multidimensional arrays:
<?php
function multidimensionalArrayMap( $func, $arr )
{
$newArr = array();
foreach( $arr as $key => $value )
{
$newArr[ $key ] = ( is_array( $value ) ? multidimensionalArrayMap( $func, $value ) : $func( $value ) );
}
return $newArr;
}
?>
pcdinh at phpvietnam dot net
17-Mar-2006 08:50
Hi benjaminhill,
You can apply a method of a instantiated class to array_maps as follows:
class Maths {
function addOne($input) {
return ($input + 1);
}
}
$maths = new Maths();
$sum = array_map(array($maths, \\\'addOne\\\'), array(1, 2));
// where $maths is the object which has been instantiated before and addOne is its method without its own parameters
var_dump($sum);
The code fragment will return:
array
0 => 2
1 => 3
However, I love a syntax like this:
$sum = array_map($maths->addOne($this), array(1, 2));
where $this should be interpreted as each values extracted from the subsequent array, which in this case is array(1, 2).
This syntax reminds me of Javascript syntax.
PHP\\\'s callback mechanism should be improved.
26-Aug-2005 06:57
Here's a function, very helpfull to me, that allows you to map your callback on mixed args.
<?php
function array_smart_map($callback) {
// Initialization
$args = func_get_args() ;
array_shift($args) ; // suppressing the callback
$result = array() ;
// Validating parameters
foreach($args as $key => $arg)
if(is_array($arg)) {
// the first array found gives the size of mapping and the keys that will be used for the resulting array
if(!isset($size)) {
$keys = array_keys($arg) ;
$size = count($arg) ;
// the others arrays must have the same dimension
} elseif(count($arg) != $size) {
return FALSE ;
}
// all keys are suppressed
$args[$key] = array_values($arg) ;
}
// doing the callback thing
if(!isset($size))
// if no arrays were found, returns the result of the callback in an array
$result[] = call_user_func_array($callback, $args) ;
else
for($i=0; $i<$size; $i++) {
$column = array() ;
foreach($args as $arg)
$column[] = ( is_array($arg) ? $arg[$i] : $arg ) ;
$result[$keys[$i]] = call_user_func_array($callback, $column) ;
}
return $result ;
}
?>
Trying with :
<?php
// $_GET is ?foo=bar1-bar2-bar3&bar=foo1
print_r(array_smart_map('explode', '-', $_GET)) ;
?>
Returns :
array(
[foo] => array(
0 => bar1
1 => bar2
2 => bar3
)
[bar] => array(
1 => foo1
)
)
david dot tulloh at infaze dot com dot au
06-Jul-2005 04:53
You can pass values to array_map by reference, essentially allowing you to use it as you would array_walk with multiple arrays as parameters.
A trivial example:
<?php
$a = array(1,2,3,4,5);
$add_func = create_function('&$x, $y', '$x+=$y;');
array_map($add_func, $a, $a);
print_r($a);
?>
Array
(
[0] => 2
[1] => 4
[2] => 6
[3] => 8
[4] => 10
)
Vinicius Cubas Brand
23-Mar-2005 05:31
The following function does exaclty the same thing of array_map. However, maintains the same index of the input arrays
<?php
function array_map_keys($param1,$param2,$param3=NULL)
{
$res = array();
if ($param3 !== NULL)
{
foreach(array(2,3) as $p_name)
{
if (!is_array(${'param'.$p_name}))
{
trigger_error(__FUNCTION__.'(): Argument #'.$p_name.' should be an array',E_USER_WARNING);
return;
}
}
foreach($param2 as $key => $val)
{
$res[$key] = call_user_func($param1,$param2[$key],$param3[$key]);
}
}
else
{
if (!is_array($param2))
{
trigger_error(__FUNCTION__.'(): Argument #2 should be an array',E_USER_WARNING);
return;
}
foreach($param2 as $key => $val)
{
$res[$key] = call_user_func($param1,$param2[$key]);
}
}
return $res;
}
?>
For instance:
<?php
$arr1 = array(
'3' => 'a',
'4' => 'b',
'5' => 'c'
);
$arr2 = array(
'3' => 'd',
'4' => 'e',
'5' => 'f'
);
$arr3 = array_map_keys(create_function('$a,$b','return $a.$b;'),$arr1,$arr2);
print_r($arr3);
?>
The result will be:
Array
(
[3] => ad
[4] => be
[5] => cf
)
endofyourself at yahoo dot com
19-Feb-2005 11:29
If you need to call a static method from array_map, this will NOT work:
<?PHP
array_map('myclass::myMethod' , $value);
?>
Instead, you need to do this:
<?PHP
array_map( array('myclass','myMethod') , $value);
?>
It is helpful to remember that this will work with any PHP function which expects a callback argument.
nd0 at gmx dot de
02-Jul-2004 04:42
array_map works also fine with create_function:
<?php
$a = array(1, 2, 3, 4, 5);
$b = array_map(create_function('$n', 'return $n*$n*$n;'), $a);
print_r($b);
?>
if you want to manipulate the elements of the array, instead to on a copy,
than take a look at array_walk:
<?php
$a = array(1, 2, 3, 4, 5);
array_walk($a, create_function('&$n', '$n = $n*$n*$n;'));
print_r($a);
?>
The Result of both is:
Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)
bishop
09-Apr-2004 05:07
Occasionally, you may find that you need to pull out a column (or several) from an array. Here's a map-like function to do that:
<?php
function &array_shear(&$arrays, $idx1 /* ... */) {
$indexes = func_get_args();
array_shift($indexes);
$newArrays = array ();
foreach (array_keys($arrays) as $arrayKey) {
$newArray = array ();
foreach ($indexes as $index) {
$newArray[$index] = $arrays[$arrayKey][$index];
unset($arrays[$arrayKey][$index]);
}
$newArrays[$arrayKey] = $newArray;
}
return $newArrays;
}
?>
So, doing this:
<?php
$t1 = array (
2 => array ('a', 'b', 'c'),
1 => array ('d', 'e', 'f'),
5 => array ('g', 'h', 'i'),
);
$t2 = array_shear($t1, 1, 0);
?>
will result in:
<?php
$t1 = array (
2 => array ( 2 => 'c', ),
1 => array ( 2 => 'f', ),
5 => array ( 2 => 'i', ),
);
$t2 = array (
2 => array ( 1 => 'b', 0 => 'a', ),
1 => array ( 1 => 'e', 0 => 'd', ),
5 => array ( 1 => 'h', 0 => 'g', ),
);
?>
stephen at mu dot com dot au
06-Jan-2003 10:02
A note when doing something allong the lines of:
<?php
class foo {
var $var;
function bar() {
array_map(array($this, "baz"), array(1,2,3));
}
function baz($arg) {
$this->var = $this->var + $arg;
}
}
?>
This will *not* work as expected. You need to pass $this by reference as with:
array_map(array(&$this, "baz"), array(1,2,3));
or you'll be making a copy of the object each time, changing a value, then throwing the result away.
dan at mojavelinux dot com
14-Jun-2002 10:07
Here is a better, more true version of a deep array_map. The only negative of this function is that the array is passed by reference, so just be aware of that. (patches welcome)
<?php
function array_map_deep(&$in_array, $in_func, $in_args = array(), $in_index = 1) {
// fix people from messing up the index of the value
if ($in_index < 1) {
$in_index = 1;
}
foreach (array_keys($in_array) as $key) {
// we need a reference, not a copy, normal foreach won't do
$value =& $in_array[$key];
// we need to copy args because we are doing
// manipulation on it farther down
$args = $in_args;
if (is_array($value)) {
array_map_deep($value, $in_func, $in_args, $in_index);
}
else {
array_splice($args, $in_index - 1, $in_index - 1, $value);
$value = call_user_func_array($in_func, $args);
}
}
return $in_array;
}
?>
This is a neat function because you can pass an array, a function, and an array of parameters, and finally, and index of where in the array of parameters for the callback function the contents you are mapping should get replaced. This index is human based (starts at 1), and can be used in something like a preg_replace callback, where the contents must be the 3rd index. Enjoy!