SunshinePHP Developer Conference 2015

array_filter

(PHP 4 >= 4.0.6, PHP 5)

array_filterFiltert Elemente eines Arrays mittels einer Callback-Funktion

Beschreibung

array array_filter ( array $array [, callable $callback ] )

Iteriert über jeden Wert im Array array und übergibt diesen der Callbackfunktion callback. Gibt die Funktion callback true zurück, so wird der aktuelle Wert von array in das Ergebnis-Array geschrieben. Die Schlüssel des Arrays bleiben erhalten.

Parameter-Liste

array

Das Array, über das iteriert werden soll

callback

Die zu verwendende Callbackfunktion

Falls die Funktion callback nicht angegeben wurde, werden alle Einträge aus array entfernt, die FALSE sind. Schauen Sie sich Konvertierung in Booleans für mehr Informationen hierzu an.

Rückgabewerte

Gibt das gefilterte Array zurück.

Beispiele

Beispiel #1 array_filter()-Beispiel

<?php
function ungerade($var)
{
    
// Gibt zurück, ob der Eingabewert ungerade ist
    
return($var 1);
}

function 
gerade($var)
{
    
// Gibt zurück, ob der Eingabewert gerade ist
    
return(!($var 1));
}

$array1 = array("a"=>1"b"=>2"c"=>3"d"=>4"e"=>5);
$array2 = array(6789101112);

echo 
"Ungerade :\n";
print_r(array_filter($array1"ungerade"));
echo 
"Gerade:\n";
print_r(array_filter($array2"gerade"));
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

Ungerade :
Array
(
    [a] => 1
    [c] => 3
    [e] => 5
)
Gerade:
Array
(
    [0] => 6
    [2] => 8
    [4] => 10
    [6] => 12
)

Beispiel #2 array_filter() ohne callback

<?php

$entry 
= array(
             
=> 'foo',
             
=> false,
             
=> -1,
             
=> null,
             
=> ''
          
);

print_r(array_filter($entry));
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

Array
(
    [0] => foo
    [2] => -1
)

Anmerkungen

Achtung

Wird das Array durch die Callbackfunktion verändert (z.B. hinzufügen oder löschen von Elementen oder ein unset-Aufruf), so ist das Verhalten dieser Funktion undefiniert.

Siehe auch

  • array_map() - Wendet eine Callback-Funktion auf die Elemente von Arrays an
  • array_reduce() - Iterative Reduktion eines Arrays zu einem Wert mittels einer Callbackfunktion
  • array_walk() - Wendet eine Benutzerfunktion auf jedem Element eines Arrays an

add a note add a note

User Contributed Notes 46 notes

up
111
Anonymous
1 year ago
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' );

?>
up
19
niehztog
5 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
up
14
marc dot vanwoerkom at fernuni-hagen dot de
10 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.
up
13
romain dot lamarche at gmail dot com
5 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);
  }
?>
up
9
lisachenko dot it at HUMAN dot gmail dot com
3 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().
up
8
tx at tshwarelo-leaka dot co dot za
1 year 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
)
up
8
webdesign at blackbyrd dot biz
5 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)
);
up
2
avl
11 months ago
nice trick:

$array_out = array_filter($array_in, function($var) use($array_other) {
            return in_array($var, $array_other) ? true : false;
});
up
3
rolf at example dot com
3 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
)
up
1
keksnicoh at googlemail dot com
1 year 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());
    });
}
?>
up
1
Hayley Watson
7 years ago
Just a simplification of my function from last month.

<?php
function partition($input, $callback=null)
{
    if(
is_null($callback))
       
$true = array_filter($input);
    else
       
$true = array_filter($input, $callback);

   
$false = array_diff_key($input, $true);
}
?>
up
1
leon at darkk dot net dot ru
7 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');
    ....
}
?>
up
2
Alix Axel
1 year ago
If you need this function to return falsy results (like "0"), yet discard truly empty ones (that have a 0 string length, like null, false, ''), you can use strlen() as the callback:

<?php
array_filter
($array, 'strlen');
?>
up
1
breich at reich-consulting dot net
3 years ago
I built the following array_remove_keys() function to
remove one or more keys from an array.

<?php

function array_remove_keys($array, $keys = array()) {

   
// If array is empty or not an array at all, don't bother
    // doing anything else.
   
if(empty($array) || (! is_array($array))) {
        return
$array;
    }

   
// If $keys is a comma-separated list, convert to an array.
   
if(is_string($keys)) {
       
$keys = explode(',', $keys);
    }

   
// At this point if $keys is not an array, we can't do anything with it.
   
if(! is_array($keys)) {
        return
$array;
    }

   
// array_diff_key() expected an associative array.
   
$assocKeys = array();
    foreach(
$keys as $key) {
       
$assocKeys[$key] = true;
    }

    return
array_diff_key($array, $assocKeys);
}

// Example:
$data = array(
   
'name' => 'Brian',
   
'address1' => '98 Market St.',
   
'address2' => 'N/A'
);

// Output before array_remove_keys()
var_dump($data);

// Remove address2 key.
$data = array_remove_keys($data, 'address2');

// Output after array_remove_keys()
var_dump($data);

/* Output:

array(3) {
  ["name"]=>
  string(5) "Brian"
  ["address1"]=>
  string(13) "98 Market St."
  ["address2"]=>
  string(3) "N/A"
}
array(2) {
  ["name"]=>
  string(5) "Brian"
  ["address1"]=>
  string(13) "98 Market St."
}
*/
?>
up
1
chrisstocktonaz at gmail dot com
5 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');
}
?>
up
1
John Erck: erck0006 at junkyo dot gmail dot com
2 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 */
up
1
manwe at inversion dot pl
1 month 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');
up
1
marc dot gray at gmail dot com
5 months 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 $array above without processing it through array_values() first.
up
1
Anonymous
6 months ago
<?php
function arrayFilter($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;
}
?>
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2
jtreminio at gmail dot com
2 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();
?>
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1
tomasz at trejderowski dot pl
1 year 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.
up
1
pavian at gmail dot com
1 year 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);

?>
up
0
m dot abbasian at outlook dot com
4 days 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
*/
?>
up
0
qeremy [atta] gmail [dotta] com
1 year 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
)
*/
?>
up
1
spam dot 2011 at rebell dot at
2 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"
up
0
Peter Robinett
4 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.
up
0
acid24 at gmail dot com
4 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)
}
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-2
g dot kuizinas at anuary dot com
1 year 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);
?>
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0
Ant P.
4 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) });
?>
up
0
mewsterus at yahoo dot com
5 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.
up
1
Martin
7 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.
up
0
darren at dazwin dot com
6 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;
}
?>
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0
sami
6 years ago
Yes, it may remove NULLS, but it also removes anything that factors to a FALSE as well; like FALSE and ZERO. :/
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0
quecoder at gmail
6 years ago
// my implementation for array_filter 

function my_array_filter($array,$function,$preserve=true)
        {   
            $return = array();
            foreach ($array as $k=>$v)
                {
                    if($function($v)==true) $return[$k]=$v;
                }
                if($preserve) return $return;
                else return array_values($return);
        }
       
function odd($value)
        {
            return ($value & 1);
        }       
   
$oddonly = array (1,2,3,4,5,6,7,8,9);
print_r(my_array_filter($oddonly,'odd',1));   

//output    
//Array ( [0] => 1 [2] => 3 [4] => 5 [6] => 7 [8] => 9 )

//Khaled Mohammed
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-1
WASD
6 years ago
You can easily delete all NULL elements from array with following statement:

<?php
$arr
= array_filter($arr);
?>
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0
Fladnag - bahatest at ifrance dot com
8 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
)
?>
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1
ajohnson at speakeasy dot org
12 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);
?>
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0
Jeremy
10 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**
        )
)
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0
redshift at pandora dot be
11 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 :-)
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0
skd2 at ece dot msstate dot edu
11 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.
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-1
Maxwel Leite
10 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;
}
?>
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-1
espertalhao04 at hotmail dot com
1 year ago
breich at reich-consulting dot net  made an awesome function, but it has a poor performance, and is bloated.

here is a shorter version:
<?php
function array_remove_keys($array, $keys = array(), $callback=null) {
    if(empty(
$array) || (! is_array($array))) {
        return
$array;
    }

    if(
is_string($keys) && !is_array($keys=explode(',',$keys)))
    {
        return
$array;
    }
   
    foreach(
$keys as $key) {
       
$key=trim($key,' ');
        if(!
$callback || !$callback($array[$key],$key))
            unset(
$array[$key]);
    }
    return
$array;
}
?>

i decided to let here stay 2 conditions, even though they can be rewritten to 1.

unsetting is faster than array_diff_keys.

sometimes, people separate strings like 'a, b, c' or 'a , b , c'...

i added support for those, since they are essentially the same list.

i also added a callback option, which you specify a function and it will give the value and the key to it.

p.s.: php uses short-circuit evaluation. example:
!$callback || !$callback($array[$key],$key)

if $callback is empty, it doesn't try to run $callback().
why?
because !$callback || !$callback($array[$key],$key) will be true, no matter the value of !$callback().
so, to save resources and time, php jumps if !$callback is true
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-1
ydotzhangatwriwindberdotorg
8 years ago
I have written a function that will filter an array by the frequency of
element value in the array.  This may be useful to some people.

<?php
/////////////////////////////////////////////////////////////////
//    Filter an array by value freguebcy
//    Input: $array
//    cut-off: $frequency (>=1)
//    result option option: 1=$frequency and higher
//          0=$frequency only
//          -1=$frequency and lower
/////////////////////////////////////////////////////////////////
function filter_array($array, $frequency = 2, $include = 1){
   
$freg = array_count_values($array);
    if(
$frequency<1){
       print
"** frequency cut-off should be >= 1! **\n";
       return
false;
    }
    foreach(
$freg as $k => $v){
        if(
$include == 0){
            if(
$frequency != $v){
               
$freg[$k] = 0;
            }
        }elseif(
$include > 0){
            if(
$frequency > $v){
               
$freg[$k] = 0;
            }
        }else{
            if(
$frequency < $v){
               
$freg[$k] = 0;
            }
        }
    }
   
$filtered = array_filter($freg);
   
$values = array_keys($filtered);
    return
array_intersect($array,$values);
}
?>
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-1
mchargue at usc dot edu
5 years ago
Wanting to pass an additional to parameter to the callback function?  This worked for me, there's probably another way to accomplish this task but just so you see how it can be done.  (I actually used this technique to strip old dates out of an array) :

<?php
//define in global scope so functions can access
$var_to_pass = null;

function
myfilter($input_var_outer,$param) {

    global
$var_to_pass;
   
$var_to_pass = $param;

    function
mycallback($input_var_inner) {
      global
$var_to_pass;
      return (
$input_var_inner>$var_to_pass) ? true : false;
    }

   
$return_arr = array_filter($input_var_outer,'mycallback');
   
//re-key if you want
   
$return_arr = array_merge(array(),$return_arr);
    return
$return_arr;

}

$min = 5;
$a = array(1,3,5,7,9);

//remove elements from array that are not greater than $min
$a = myfilter($a,$min);

echo
"<pre>";
print_r($a);
echo
"</pre>";
?>

--

Output:
Array
(
    [0] => 7
    [1] => 9
)
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-1
ajohnson at speakeasy dot org
12 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($array2);
?>
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-3
xert
9 years ago
According to a simple test with array_filter($array) and array_diff($array, array('')) is array_filter 2.5 times faster than array_diff when deleting empty entries.
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