If you want a quick way to remove NULL, FALSE and Empty Strings (""), but leave values of 0 (zero), you can use the standard php function strlen as the callback function:
eg:
<?php
// removes all NULL, FALSE and Empty Strings but leaves 0 (zero) values
$result = array_filter( $array, 'strlen' );
?>
array_filter
(PHP 4 >= 4.0.6, PHP 5, PHP 7)
array_filter — Filters elements of an array using a callback function
Description
Iterates over each value in the array
passing them to the callback function.
If the callback function returns TRUE, the
current value from array is returned into
the result array. Array keys are preserved.
Parameters
-
array -
The array to iterate over
-
callback -
The callback function to use
If no
callbackis supplied, all entries ofarrayequal toFALSE(see converting to boolean) will be removed. -
flag -
Flag determining what arguments are sent to
callback:-
ARRAY_FILTER_USE_KEY- pass key as the only argument tocallbackinstead of the value -
ARRAY_FILTER_USE_BOTH- pass both value and key as arguments tocallbackinstead of the value
callbackinstead. -
Return Values
Returns the filtered array.
Changelog
| Version | Description |
|---|---|
| 5.6.0 |
Added optional flag parameter and constants
ARRAY_FILTER_USE_KEY and
ARRAY_FILTER_USE_BOTH
|
Examples
Example #1 array_filter() example
<?php
function odd($var)
{
// returns whether the input integer is odd
return $var & 1;
}
function even($var)
{
// returns whether the input integer is even
return !($var & 1);
}
$array1 = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5];
$array2 = [6, 7, 8, 9, 10, 11, 12];
echo "Odd :\n";
print_r(array_filter($array1, "odd"));
echo "Even:\n";
print_r(array_filter($array2, "even"));
?>
The above example will output:
Odd :
Array
(
[a] => 1
[c] => 3
[e] => 5
)
Even:
Array
(
[0] => 6
[2] => 8
[4] => 10
[6] => 12
)
Example #2 array_filter() without
callback
<?php
$entry = [
0 => 'foo',
1 => false,
2 => -1,
3 => null,
4 => '',
5 => '0',
6 => 0,
];
print_r(array_filter($entry));
?>
The above example will output:
Array
(
[0] => foo
[2] => -1
)
Example #3 array_filter() with
flag
<?php
$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];
var_dump(array_filter($arr, function($k) {
return $k == 'b';
}, ARRAY_FILTER_USE_KEY));
var_dump(array_filter($arr, function($v, $k) {
return $k == 'b' || $v == 4;
}, ARRAY_FILTER_USE_BOTH));
?>
The above example will output:
array(1) {
["b"]=>
int(2)
}
array(2) {
["b"]=>
int(2)
["d"]=>
int(4)
}
Notes
Caution
If the array is changed from the callback function (e.g. element added, deleted or unset) the behavior of this function is undefined.
See Also
- array_map() - Applies the callback to the elements of the given arrays
- array_reduce() - Iteratively reduce the array to a single value using a callback function
- array_walk() - Apply a user supplied function to every member of an array
add a note
User Contributed Notes 48 notes
Anonymous ¶
6 years ago
Peter Robinett ¶
9 years ago
Because array_filter() preserves keys, you should consider the resulting array to be an associative array even if the original array had integer keys for there may be holes in your sequence of keys. This means that, for example, json_encode() will convert your result array into an object instead of an array. Call array_values() on the result array to guarantee json_encode() gives you an array.
niehztog ¶
10 years ago
In case you are interested (like me) in filtering out elements with certain key-names, array_filter won't help you. Instead you can use the following:
<?php
$arr = array( 'element1' => 1, 'element2' => 2, 'element3' => 3, 'element4' => 4 );
$filterOutKeys = array( 'element1', 'element4' );
$filteredArr = array_diff_key( $arr, array_flip( $filterOutKeys ) )
?>
Result will be something like this:
['element2'] => 2
['element3'] => 3
manwe at inversion dot pl ¶
5 years ago
array_filter remove also FALSE and 0. To remove only NULL's use:
$af = [1, 0, 2, null, 3, 6, 7];
function is_not_null($val){
return !is_null($val);
}
$af = array_filter($af, 'is_not_null');
rolf at example dot com ¶
8 years ago
Here is how you could easily delete a specific value from an array with array_filter:
<?php
$array = array (1, 3, 3, 5, 6);
$my_value = 3;
$filtered_array = array_filter($array, function ($element) use ($my_value) { return ($element != $my_value); } );
print_r($filtered_array);
?>
output:
Array
(
[0] => 1
[3] => 5
[4] => 6
)
robbieaverill at gmail dot com ¶
4 years ago
If you want to use array_filter with a class method as the callback, you can use a psuedo type callback like this:
<?php
class Test
{
public function doFilter($array)
{
return array_filter($array, array($this, 'callbackMethodName'));
}
protected function callbackMethodName($element)
{
return $element % 2 === 0;
}
}
$example = new Test;
print_r($example->doFilter(range(1, 10)));
?>
Will return even numbers.
marc dot vanwoerkom at fernuni-hagen dot de ¶
15 years ago
Some of PHP's array functions play a prominent role in so called functional programming languages, where they show up under a slightly different name:
<?php
array_filter() -> filter(),
array_map() -> map(),
array_reduce() -> foldl() ("fold left")
?>
Functional programming is a paradigm which centers around the side-effect free evaluation of functions. A program execution is a call of a function, which in turn might be defined by many other functions. One idea is to use functions to create special purpose functions from other functions.
The array functions mentioned above allow you compose new functions on arrays.
E.g. array_sum = array_map("sum", $arr).
This leads to a style of programming that looks much like algebra, e.g. the Bird/Meertens formalism.
E.g. a mathematician might state
map(f o g) = map(f) o map(g)
the so called "loop fusion" law.
Many functions on arrays can be created by the use of the foldr() function (which works like foldl, but eating up array elements from the right).
I can't get into detail here, I just wanted to provide a hint about where this stuff also shows up and the theory behind it.
webdesign at blackbyrd dot biz ¶
9 years ago
Here's a function that will filter a multi-demensional array. This filter will return only those items that match the $value given
<?php
/*
* filtering an array
*/
function filter_by_value ($array, $index, $value){
if(is_array($array) && count($array)>0)
{
foreach(array_keys($array) as $key){
$temp[$key] = $array[$key][$index];
if ($temp[$key] == $value){
$newarray[$key] = $array[$key];
}
}
}
return $newarray;
}
?>
Example:
<?php
$results = array(
0 => array('key1' => '1', 'key2' => 2, 'key3' => 3),
1 => array('key1' => '12', 'key2' => 22, 'key3' => 32)
);
$nResults = filter_by_value($results, 'key2', '2');
?>
Output :
array(
0 => array('key1' => '1', 'key2' => 2, 'key3' => 3)
);
romain dot lamarche at gmail dot com ¶
10 years ago
This function filters an array and remove all null values recursively.
<?php
function array_filter_recursive($input)
{
foreach ($input as &$value)
{
if (is_array($value))
{
$value = array_filter_recursive($value);
}
}
return array_filter($input);
}
?>
Or with callback parameter (not tested) :
<?php
function array_filter_recursive($input, $callback = null)
{
foreach ($input as &$value)
{
if (is_array($value))
{
$value = array_filter_recursive($value, $callback);
}
}
return array_filter($input, $callback);
}
?>
g dot kuizinas at anuary dot com ¶
6 years ago
<?php
function array_filter_recursive ($data) {
$original = $data;
$data = array_filter($data);
$data = array_map(function ($e) {
return is_array($e) ? array_filter_recursive($e) : $e;
}, $data);
return $original === $data ? $data : array_filter_recursive($data);
}
$data = ['a' => 0, 'b' => [], 'c' => [[]], 'd' => [[[[]]]], 'e' => 'foo', 'f' => [[['a']]], [true], [[],['a'], [true, false]]];
$data = array_filter_recursive($data);
?>
lisachenko dot it at HUMAN dot gmail dot com ¶
8 years ago
You can access the current key of array by passing a reference to array into callback function and call key() and next() method in the callback function:
<?php
$data = array('first' => 1, 'second' => 2, 'third' => 3);
$data = array_filter($data, function ($item) use (&$data) {
echo "Filtering key ", key($data), '<br>', PHP_EOL;
next($data);
return false;
});
?>
However be careful with array internal pointer or use reset() method before calling array_filter().
yuzhen huang ¶
4 years ago
from php 5.3, we use anonymous function as second argument:
$a = array('a'=>1, 'b'=>2, 'c'=>false, 'd'=>0);
$b = array_filter($a, function($v){return $v !== 0;});
var_dump($b);
output:
array(3) {
'a' =>
int(1)
'b' =>
int(2)
'c' =>
bool(false)
}
tx at tshwarelo-leaka dot co dot za ¶
6 years ago
To get rid of all white space in an array without looping.
<?php
$array = array(5, " ", 2, NULL, 13, "", 7, "\n", 4, "\t");
print_r($array);
$result = array_filter($array, create_function('$a','return preg_match("#\S#", $a);'));
print_r($result);
?>
Array
(
[0] => 5
[1] =>
[2] => 2
[3] =>
[4] => 13
[5] =>
[6] => 7
[7] =>
[8] => 4
[9] =>
)
Array
(
[0] => 5
[2] => 2
[4] => 13
[6] => 7
[8] => 4
)
jtreminio at gmail dot com ¶
6 years ago
You can use array_filter from within a class to access a protected method from that same class:
<?php
class Bar {
public function foo()
{
$array1 = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
print_r(array_filter($array1, array($this, 'naz')));
}
protected function baz($var)
{
return($var & 1);
}
}
$bar = new Bar();
$bar->foo();
?>
nicolaj dot knudsen at gmail dot com ¶
2 years ago
If you like me have some trouble understanding example #1 due to the bitwise operator (&) used, here is an explanation.
The part in question is this callback function:
<?php
function odd($var)
{
// returns whether the input integer is odd
return($var & 1);
}
?>
If given an integer this function returns the integer 1 if $var is odd and the integer 0 if $var is even.
The single ampersand, &, is the bitwise AND operator. The way it works is that it takes the binary representation of the two arguments and compare them bit for bit using AND. If $var = 45, then since 45 in binary is 101101 the operation looks like this:
45 in binary: 101101
1 in binary: 000001
------
result: 000001
Only if the last bit in the binary representation of $var is changed to zero (meaning that the value is even) will the result change to 000000, which is the representation of zero.
marc dot gray at gmail dot com ¶
5 years ago
My favourite use of this function is converting a string to an array, trimming each line and removing empty lines:
<?php
$array = array_filter(array_map('trim', explode("\n", $string)), 'strlen');
?>
Although it states clearly that array keys are preserved, it's important to note this includes numerically indexed arrays. You can't use a for loop on $array above without processing it through array_values() first.
Martin ¶
12 years ago
This function trims empty strings from the beginning and end of an array.
It's useful when outputing plaintext files on a page and you want to skip empty lines at the beginning and end, but not within the text.
<?php
function array_trim($array) {
while (strlen(reset($array)) === 0) {
array_shift($array);
}
while (strlen(end($array)) === 0) {
array_pop($array);
}
return $array;
}
?>
You might want to trim each element too.
redshift at pandora dot be ¶
16 years ago
Hi all,
Here's a function that will look trough an array, and removes the array member when the search string is found.
<?php
function array_clean ($input, $delete = false, $caseSensitive = false)
{
$i = 0;
while($i < count($input))
{
if($delete)
{
if($caseSensitive)
{
if(!strstr($input[$i] ,$delete))
{
$return[] = $input[$i];
}
}
else
{
if(!stristr($input[$i], $delete))
{
$return[] = $input[$i];
}
}
}
else
{
if(!empty($input[$i]))
{
$return[] = $input[$i];
}
}
$i++;
}
return $return;
}
?>
array array_clean(array input [, string needle [, boolean case sensitive]])
if needle is left empty, the function will delete the array members that have no value (this means if it's empty).
NOTE: It rebuilds the array from scratch, so keys begin with 0, like you would create a new array.
Example:
$array = array("John", "Doe", "Macy");
$array = array_clean($array, "doe", false);
print_r($array);
would return:
array
(
[0] => John
[1] => Macy
)
Hopes this helps someone :-)
iancudanielc () gmail ! com ¶
4 years ago
If you want to pass the key to the callback function before PHP 5.6.0 (when the flag parameter wasn't implemented):
<?php
$result = array_filter(array_keys($array), 'is_int');
?>
ajohnson at speakeasy dot org ¶
17 years ago
be careful with the above function "array_delete"'s use of the stristr function, it could be slightly misleading. consider the following:
<?php
function array_delete($array, $filterforsubstring){
$thisarray = array ();
foreach($array as $value)
if(stristr($value, $filterforsubstring)===false && strlen($value)>0)
$thisarray[] = $value;
return $thisarray;
}
function array_delete2($array, $filterforstring, $removeblanksflag=0){
$thisarray = array ();
foreach($array as $value)
if(!(stristr($value, $filterforstring) && strlen($value)==strlen($filterforstring))
&& !(strlen($value)==0 && $removeblanksflag))
$thisarray[] = $value;
return $thisarray;
}
function array_delete3($array, $filterfor, $substringflag=0, $removeblanksflag=0){
$thisarray = array ();
foreach($array as $value)
if(
!(stristr($value, $filterfor)
&& ($substringflag || strlen($value)==strlen($filterfor))
)
&& !(strlen($value)==0 && $removeblanksflag)
)
$thisarray[] = $value;
return $thisarray;
}
$array1 = array ('the OtHeR thang','this', 'that', 'OtHer','', 9, 101, 'fifty', ' oTher', 'otHer ','','other','Other','','other blank things');
echo "<pre>array :\n";
print_r($array1);
$array2=array_delete($array1, "Other");
echo "array_delete(\$array1, \"Other\"):\n";
print_r($array2);
$array2=array_delete2($array1, "Other");
echo "array_delete2(\$array1, \"Other\"):\n";
print_r($array2);
$array2=array_delete2($array1, "Other",1);
echo "array_delete2(\$array1, \"Other\",1):\n";
print_r($array2);
$array2=array_delete3($array1, "Other",1);
echo "array_delete3(\$array1, \"Other\",1):\n";
print_r($array2);
$array2=array_delete3($array1, "Other",0,1);
echo "array_delete3(\$array1, \"Other\",0,1):\n";
print_r($array2);
?>
avl ¶
5 years ago
nice trick:
$array_out = array_filter($array_in, function($var) use($array_other) {
return in_array($var, $array_other) ? true : false;
});
raj at rafa dot eu dot org ¶
1 year ago
Here is a simple array_grep() function that works similarly to 'grep' command, ie. filters array elements that match a given regular expression.
It's a bit ugly as it uses a global variable $__array_grep_regex to pass the regular expression to the callback function. I couldn't find a better way to do it. Anyway, here it is:
<?php
$__array_grep_regex="";
function array_grep($arr, $regex) {
global $__array_grep_regex;
$__array_grep_regex=$regex;
return array_filter($arr, function($val) {
global $__array_grep_regex;
return preg_match($__array_grep_regex, $val);
});
}
?>
Anonymous ¶
1 year ago
<?php
function odd($var)
{
// returns whether the input integer is odd
return($var & 1);
}
function even($var)
{
// returns whether the input integer is even
return(!($var & 1));
}
$array1 = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
$array2 = array(6, 7, 8, 9, 10, 11, 12);
echo "Odd :\n";
print_r(array_filter($array1, "odd"));
echo "Even:\n";
print_r(array_filter($array2, "even"));
?>
shouldtnt the '&' operators in the function be a '%' ? Is this a typo or do I not undertsand PHP
bimal at sanjaal dot com ¶
1 year ago
I needed to filter specific files. glob was a good option but had issues being case sensitive. And at the same time, I had to filter the directory names like ".", "..", ".git", etc which could be complex.
I used a snippet as below, where I could implement this complex filter. Just modify your method: image_file.
<?php
class handlers
{
private $path;
public function __construct($path)
{
$this->path = realpath($path);
}
public function image_file($file="abc.png")
{
$is_image_file = is_file($this->path."/".$file);
return $is_image_file;
}
}
$path = realpath("../../gallery-200x400");
$files = scandir($path);
print_r($files);
$files = array_filter($files, array(new handlers($path), "image_file"), ARRAY_FILTER_USE_BOTH);
print_r($files);
?>
nsrwork(dog)gmail ¶
1 year ago
If we need to find array in the multidimenssional array (with ignore keys!)
// where we will find
$arrays = [
['c','b','a'], ['e','f','g'], ['j','h','t']
];
// what we will find
$array = ['a','b','c'];
function isArrayExist($arrays, $array)
{
return (bool) array_filter($arrays, function ($_array) use ($array) {
return !array_diff($array, $_array);
});
}
//Output
true
jimmmy dot chief at gmail dot com ¶
2 years ago
Hi, when using your annonymous function to filter the array, DO NOT cast returning value as bool.
Any value won't be filtered that way.
example:
$reader = array(
1,2,3,2,1,2,1,2,1
);
$a = array_filter($reader, function ($var) {
return (bool) $var == 2; //returns whole array
return $var == 2; //filter values
});
echo count($a); //9 with cast as bool, 4 otherwise
njt1982 at yahoo dot com ¶
4 years ago
If you have an array of KV pairs and you want all the items where a value is X, you dont need to make a callback for array_filter. You can use array_intersect:
<?php
print_r(array_intersect(
array(
'a' => 1,
'b' => 1,
'c' => 1,
'd' => 2,
'e' => 2,
'f' => 2,
),
array(1)
));
Array
(
[a] => 1
[b] => 1
[c] => 1
)
?>
The advantage of this approach is you can pass variables into the second array without needing to worry about variable scope and function parameters for array_filter.
qeremy [atta] gmail [dotta] com ¶
5 years ago
Here is key-passed array_filter function.
<?php
function arrayfilter(array $array, callable $callback = null) {
if ($callback == null) {
$callback = function($key, $val) {
return (bool) $val;
};
}
$return = array();
foreach ($array as $key => $val) {
if ($callback($key, $val)) {
$return[$key] = $val;
}
}
return $return;
}
$test_array = array('foo', 'a' => 'the a', 'b' => 'the b', 11 => 1101, '', null, false, 0);
$array = arrayfilter($test_array, function($key, $val) {
return is_string($key);
});
print_r($array);
/*
Array
(
[a] => the a
[b] => the b
)
*/
$array = arrayfilter($test_array);
print_r($array);
/*
Array
(
[0] => foo
[a] => the a
[b] => the b
[11] => 1101
)
*/
?>
chrisstocktonaz at gmail dot com ¶
10 years ago
I use the following to see if a array consist of scalar values or null, but of course you could mix it up using any of the is_ functions.
<?php
if(count($data) !== count(array_filter($data, 'is_scalar') + array_filter($data, 'is_null'))) {
throw new Exception('Array did not consist of scalar and null values');
}
?>
darren at dazwin dot com ¶
10 years ago
Regarding comment about trimming empty strings, the code posted will get into an infinite loop if the array is reduced to zero elements. The following might be better:
<?php
function array_trim($array) {
while (!empty($array) and strlen(reset($array)) === 0) {
array_shift($array);
}
while (!empty($array) and strlen(end($array)) === 0) {
array_pop($array);
}
return $array;
}
?>
Maxwel Leite ¶
15 years ago
For any type of array. Basead in redshift code.
<?php
function array_clean ($array, $todelete = false, $caseSensitive = false) {
foreach($array as $key => $value) {
if(is_array($value)) {
$array[$key] = array_clean($array[$key], $todelete, $caseSensitive);
}
else {
if($todelete) {
if($caseSensitive) {
if(strstr($value ,$todelete) !== false)
unset($array[$key]);
}
else {
if(stristr($value, $todelete) !== false)
unset($array[$key]);
}
}
elseif (empty($value)) {
unset($array[$key]);
}
}
}
return $array;
}
?>
ajohnson at speakeasy dot org ¶
17 years ago
I was looking for a function to delete values from an array and thought I had found it in array_filter(), however, I *didn't* want the keys to be preserved *and* I needed blank values cleaned out of the array as well. I came up with the following (with help from many of the above examples):
<?php
function array_delete($array, $filterfor){
$thisarray = array ();
foreach($array as $value)
if(stristr($value, $filterfor)===false && strlen($value)>0)
$thisarray[] = $value;
return $thisarray;
}
$array1 = array ('OtHeR','this', 'that', 'Other','', 9, 101, 'fifty', 'other','','');
echo "<pre>array :\n";
print_r($array1);
$array2=array_delete($array1, "Other");
echo "filtered:\n";
print_r($array2);
?>
skd2 at ece dot msstate dot edu ¶
16 years ago
The following function modifies the supplied array recursively so that filtering is performed on multidimentional arrays as well, while preserving keys.
<?php
function array_cleanse(&$arr){
$temp = array();
reset($arr);
if(count($arr) == 0) return "";
foreach($arr as $key=>$val):
(is_array($val))? array_cleanse($val) : NULL;
($val)? $temp[$key] = $val : NULL;
endforeach;
$arr = $temp;
reset($arr);
}
?>
$arr1 = array('a'=>20,'b'=>array(''),'c'=>array(1,0,2),'d'=>0);
array_cleanse($arr1);
$arr1 will be array('a'=>20,'c'=>array(1,2))
array_filter may not be used as it does not modify the array within itself.
John Erck: erck0006 at junkyo dot gmail dot com ¶
7 years ago
<?php
// ARRAY FILTER RECURSIVE USING CLASS, STATIC METHOD, AND ANONYMOUS CALLBACK FUNCTION
// NOTE THAT THE CALLBACK HAS ACCESS TO BOTH THE KEY AND VALUE
// THE CLASS (FOR YOU TO COPY)
class ArrayUtil
{
public static function FilterRecursive(Array $source, $fn)
{
$result = array();
foreach ($source as $key => $value)
{
if (is_array($value))
{
$result[$key] = self::FilterRecursive($value, $fn);
continue;
}
if ($fn($key, $value))
{
$result[$key] = $value; // KEEP
continue;
}
}
return $result;
}
}
// EXAMPLE ANONYMOUS CALLBACK FUNCTION
$fn = function ($key, $value)
{
if (strpos($key, 'drop') !== FALSE)
{
return FALSE; // DROP
}
return TRUE; // KEEP
};
// EXAMPLE PRE FILTER TEST DATA
$preFilter = array(
'a' => 'one',
'b' => array(
'example_drop' => 'filter me out',
'example_keep' => 'keep me',
),
'c' => 'three',
);
// EXAMPLE USAGE CODE
echo '// print_r($preFilter);' . "\n";
print_r($preFilter);
$postFilter = ArrayUtil::FilterRecursive($preFilter, $fn);
echo "\n";
echo '// print_r($postFilter);' . "\n";
print_r($postFilter);
/* OUTPUT OPEN
// print_r($preFilter);
Array
(
[a] => one
[b] => Array
(
[example_drop] => filter me out
[example_keep] => keep me
)
[c] => three
)
// print_r($postFilter);
Array
(
[a] => one
[b] => Array
(
[example_keep] => keep me
)
[c] => three
)
OUTPUT CLOSE */
acid24 at gmail dot com ¶
9 years ago
A function that allows filtering an array by keys:
<?php
function array_filter_key( $input, $callback ) {
if ( !is_array( $input ) ) {
trigger_error( 'array_filter_key() expects parameter 1 to be array, ' . gettype( $input ) . ' given', E_USER_WARNING );
return null;
}
if ( empty( $input ) ) {
return $input;
}
$filteredKeys = array_filter( array_keys( $input ), $callback );
if ( empty( $filteredKeys ) ) {
return array();
}
$input = array_intersect_key( array_flip( $filteredKeys ), $input );
return $input;
}
?>
Example:
<?php
$input = array_flip( range( 'a', 'z' ) );
$consonants = array_filter_key( $arr, function( $elem ) {
$vowels = "aeiou";
return strpos( $vowels, strtolower( $elem ) ) === false;
} );
?>
Outputs:
array(21) {
["b"]=>
int(1)
["c"]=>
int(2)
["d"]=>
int(3)
["f"]=>
int(5)
["g"]=>
int(6)
["h"]=>
int(7)
["j"]=>
int(9)
["k"]=>
int(10)
["l"]=>
int(11)
["m"]=>
int(12)
["n"]=>
int(13)
["p"]=>
int(15)
["q"]=>
int(16)
["r"]=>
int(17)
["s"]=>
int(18)
["t"]=>
int(19)
["v"]=>
int(21)
["w"]=>
int(22)
["x"]=>
int(23)
["y"]=>
int(24)
["z"]=>
int(25)
}
tomasz at trejderowski dot pl ¶
6 years ago
Read "callback" parameter note with understanding (as well as "converting to boolean" chapter). Keep in midn, that 0, both:
* integer: 0 and
* float: 0.00
evaluates to boolean FALSE! And therefore all array nodes, that have such value WILL ALSO BE FILTERED by array_filter(), with default call back. Unless you provide your own callback function, that will (for example) filter only empty strings and NULLs, but leave "zeros" untouched.
Some people (including me) might be surprised to find this out.
spam dot 2011 at rebell dot at ¶
7 years ago
If you have not noticed already - array_filter() can be used to remove empty elements, since an empty string considered "false", if you not specify a callback
Keep in mind, that this will remove also some other values - so if you want a quick "remove empty elements from array" this function will be fine, as long as you dont have anything to keep, which casts to "false"
m dot abbasian at outlook dot com ¶
4 years ago
If you want a quick way to Find Numbers ( remove NULL, FALSE and Empty Strings (""), all Strings) but leave values of 0 (zero)
eg:
<?php
/*
Find Numbers (removes all NULL, FALSE and Empty Strings, all Strings) but leaves 0 (zero) values
*/
$result = array_filter( array( "0",0,1,2,3,'text' ) , 'is_numeric' );
var_dump($result);
/*
array (size=5)
0 => string '0' (length=1)
1 => int 0
2 => int 1
3 => int 2
4 => int 3
*/
?>
keksnicoh at googlemail dot com ¶
6 years ago
Usefull invertation of array_filter
<?php
$data = array(...)
$noArrayData = array_filter_inverse($data, 'is_array');
/**
* Inverts the result of the filter callback.
* @param array $data
* @param callable $f
* @return array
*/
function array_filter_inverse(array $data, callable $f)
{
return array_filter($data, function() use(&$f) {
return ! call_user_func_array($f, func_get_args());
});
}
?>
Ant P. ¶
9 years ago
If you're using filter_input_array, the values will be null on failure and anything else on success. Because array_filter by default removes false, 0 and "" you need to do extra work like this:
<?php
$input_array = filter_input_array(INPUT_GET, array(
'var1' => FILTER_VALIDATE_BOOLEAN,
'var2' => FILTER_VALIDATE_INT
));
array_filter($input_array, function($a) { return !is_null($a) });
?>
sami ¶
10 years ago
Yes, it may remove NULLS, but it also removes anything that factors to a FALSE as well; like FALSE and ZERO. :/
leon at darkk dot net dot ru ¶
12 years ago
Here is a way to get customizable filter
<?php
function blablabla() {
....
$new = getNewUidls();
class UidlFilter {
function UidlFilter($uidls) { $this->uidls = $uidls; }
function filter($metamsg) { return in_array($metamsg['uidl'], $this->uidls); }
}
$msglist = array_filter($msglist, array(new UidlFilter($new), 'filter');
....
}
?>
Jeremy ¶
15 years ago
Here is a nice little function which will apply a callback function recursively over a multidimensional array. If the callback function returns false, then it replaces the value of the array with $filtered_ouput. This function gracefully handles objects inside of arrays (and objects within objects within arrays, etc). It is specifically designed for your callback function to process on the array key's (unlike normal array_filter which filters on the values), but it could work on the array values depending on your test criteria (YMMV).
<?PHP
function array_key_filter_multi($array, $callback, $filtered_output = "")
{
$ret = array();
foreach($array as $key=>$value) {
if($callback($key,$value)) {
if(is_array($value)) {
$ret[$key] = array_key_filter_multi($value, $callback, $filtered_output);
}
elseif(is_object($value)) {
$ret[$key] = array_key_filter_multi(get_object_vars($value), $callback, $filtered_output);
}
else {
$ret[$key]=$value;
}
}
else {
$ret[$key]=$filtered_output;
}
}
return $ret;
}
?>
We use this to filter redundant data from debugging output. An example usage is:
<?
$callback_func = create_function('$key, $value', 'return ($key == "db" || $key == "smarty") ? false : true;');
echo "<PRE>" . print_r(array_key_filter_multi($_SESSION, $callback_func, "**filtered by function**"), true) . "</PRE>";
?>
Which filters all keys with "db" or "smarty" as their name (including objects which have a reference to those variables). The output of the above in a test case I did is the following:
Array
(
[userdata] => Array
(
[sid] => a130e675d380e0e9fe47897922d719ac
[not_in_db] =>
[user_id] => 1
[session_id] => 154
[permissions] => 1
[username] => tester
)
[systemobjects] => Array
(
[db] => **filtered by function**
[smarty] => **filtered by function**
)
)
Anonymous ¶
5 years ago
<?php
function arrayFilter($input, $callback = null) {
foreach($input as $key => &$value) {
if(is_array($value)) {
$value = arrayFilter($value, $callback);
if(is_array($value)) {
if((bool)$value === false) unset($input[$key]);
}
else {
if((bool)($callback ? $callback($value) : $value) === false) unset($input[$key]);
}
}
else {
if((bool)($callback ? $callback($value) : $value) === false) unset($input[$key]);
}
}
return $input;
}
?>
mewsterus at yahoo dot com ¶
10 years ago
Here's an easy way to get a combination of keys and values, such that if you don't specify a key you will get the value, and if you do specify a key you will get the key:
<?php
$array = array('One' => 'First', 'Second', 'Third', 'Four' => 'Fourth', 'Fifth');
var_dump(array_keys($array));
$names = array_filter(array_keys($array), 'is_string') + array_values($array);
ksort($array);
var_dump($names);
?>
Outputs:
array(5) {
[0]=>string(3) "One"
[1]=>int(0)
[2]=>int(1)
[3]=>string(4) "Four"
[4]=>int(2)
}
array(5) {
[0]=>string(3) "One"
[1]=>string(6) "Second"
[2]=>string(5) "Third"
[3]=>string(4) "Four"
[4]=>string(5) "Fifth"
}
Without using ksort, the keys appear before the fallback values, instead of inline and appearing like they replace them, however the keys are intact (which is why ksort works) so it's only execution order.
Fladnag - bahatest at ifrance dot com ¶
12 years ago
If you have a form with multiple checkbox having ID element as value for selection in a list, you probably have a SQL request like :
$req="SELECT ... WHERE ID IN (".implode(',', array_keys($choices)).")";
without quote before and after choices keys because they are numeric values... but in fact, they can be string values, and a SQL injection problem.
with array_filter, you can easily filter bad values :
<?php
$choices=array('A'=>'on', -1=>'on', 0=>'on', 1=>'on', 12=>'on', "1)or 1=1--"=>'on');
print_r($choices);
$choices=array_filter(array_keys($choices), 'is_numeric');
print_r($choices);
?>
will print :
<?php
Array
(
[A] => on
[-1] => on
[0] => on
[1] => on
[12] => on
[1)or 1=1--] => on
)
Array
(
[1] => -1
[2] => 0
[3] => 1
[4] => 12
)
?>
pavian at gmail dot com ¶
6 years ago
Regarding to strlen() related notes, if you want to filter NULL, FALSE and empty strings from the array, just omit callback function, it does the same trick (but easier).
<?php
$clean = array_filter($array);
?>
manuelworks at gmail dot com ¶
4 years ago
I needed to get the complete array element of a multilevel array where the values of some elements where 'x' or 'y'. Kind of a WHERE AND in a MySQL Query..
SO if you need to filter an array where 'X' = Y and 'a' = b, here you go.
<?php
/*
* getArrayElement() by @MmO12
*
* SELECT an element of an $array...
* *$array = array( 0 => array('index1' => 'a', 'index2' => 'b', 'value' => 'hello'),
1 => array('index1' => 'a', 'index2' => 'c', 'value' => 'bye'));
*
* WHERE its $indexs values are equal to...
* * $indexs = array('index1' => 'a', 'index2'=>'b');
*/
function getArrayElement($array, $indexs, $justvalsplease = false){
$newarray = false;
//verificamos el array
if(is_array($array) && count($array)>0){
//verify indexs and get # of indexs
if(is_array($indexs) && count($indexs)>0) $ninds = count($indexs);
else return false;
//search for coincidences
foreach(array_keys($array) as $key){
//index value coincidence counter.
$count = 0;
//for each index we search
foreach($indexs as $indx => $val){
//if index value is equal then counts
if($array[$key][$indx] == $val){
$count++;
}
}
//if indexes match, we get the array elements :)
if($count == $ninds){
//if you only need the vals of the first coincidence
//witch was my case by the way...
if($justvalsplease) return $array[$key];
else $newarray[$key] = $array[$key];
}
}
}
return $newarray;
}
?>
/*******
Example
********/
<?php
//array
$array = array( 0 => array('index1' => 'a', 'index2' => 'b', 'value' => 'hello'),
1 => array('index1' => 'a', 'index2' => 'c', 'value' => 'bye'),
2 => array('index1' => 'b', 'index2' => 'a', 'value' => 'hi'));
//indexes
$indexs = array('index1' => 'a', 'index2'=>'b');
//aaand we get the element we want.
$element = getArrayElement($array, $indexs);
print_r($element);
/***prints ***/
Array
(
[0] => Array
(
[index1] => a
[index2] => b
[value] => hello
)
)?>
IF you want only the array inside the elements just set $justvalsplease true like this
<?php
$element = getArrayElement($array, $indexs,true);
?>
And you will get just the element content
<?php
Array
(
[index1] => a
[index2] => b
[value] => hello
)
?>
