array_slice

(PHP 4, PHP 5, PHP 7, PHP 8)

array_sliceEstrae un sottoinsieme da un array

Descrizione

array_slice(array $array, int $offset, int $ length = ?): array

array_slice() restituisce la sequenza di elementi dell'array array come specificato dai parametri offset e length .

Se offset è positivo, la sequenza comincerà da quell'offset in array. Se offset è negativo, la sequenza comincerà alla distanza offset dalla fine di array.

Se length è specificata ed è positiva, la sequenza conterrà quel numero di elementi. Se length è specificata ed è negativa la sequenza si fermerà a quel numero di elementi dalla fine dell'array. Se viene omessa, la sequenza conterrà tutto da offset fino alla fine di array.

Si noti che array_slice() ignorerà le chiavi dell'array, e calcolerè gli spiazzamenti e le lunghezze basandosi sulle posizioni correnti degli elementi nell'array.

Example #1 esempi di array_slice()

<?php
$input
= array("a", "b", "c", "d", "e");

$output = array_slice($input, 2); // restituisce "c", "d" e "e"
$output = array_slice($input, 2, -1); // restituisce "c", "d"
$output = array_slice($input, -2, 1); // restituisce "d"
$output = array_slice($input, 0, 3); // restituisce "a", "b" e "c"
?>

Vedere anche array_splice() e unset().

add a note add a note

User Contributed Notes 20 notes

up
50
taylorbarstow at the google mail service
18 years ago
Array slice function that works with associative arrays (keys):

function array_slice_assoc($array,$keys) {
    return array_intersect_key($array,array_flip($keys));
}
up
19
Ray.Paseur often uses Gmail
11 years ago
<?php
// CHOP $num ELEMENTS OFF THE FRONT OF AN ARRAY
// RETURN THE CHOP, SHORTENING THE SUBJECT ARRAY
function array_chop(&$arr, $num)
{
   
$ret = array_slice($arr, 0, $num);
   
$arr = array_slice($arr, $num);
    return
$ret;
}
up
4
nathan dot fiscaletti at gmail dot com
6 years ago
If you want an associative version of this you can do the following:

function array_slice_assoc($array,$keys) {
    return array_intersect_key($array,array_flip($keys));
}

However, if you want an inverse associative version of this, just use array_diff_key instead of array_intersect_key.

function array_slice_assoc_inverse($array,$keys) {
    return array_diff_key($array,array_flip($keys));
}

Example:

$arr = [
    'name' => 'Nathan',
    'age' => 20,
    'height' => 6
];

array_slice_assoc($arr, ['name','age']);

will return

Array (
     'name' = 'Nathan',
     'age' = 20
)

Where as

array_slice_assoc_inverse($arr, ['name']);

will return

Array (
    'age' = 20,
    'height' = 6
)
up
12
worldclimb at 99gmail99 dot com
16 years ago
array_slice can be used to remove elements from an array but it's pretty simple to use a custom function.

One day array_remove() might become part of PHP and will likely be a reserved function name, hence the unobvious choice for this function's names.

<?
function arem($array,$value){
   
$holding=array();
    foreach(
$array as $k => $v){
        if(
$value!=$v){
           
$holding[$k]=$v;
        }
    }   
    return
$holding;
}

function
akrem($array,$key){
   
$holding=array();
    foreach(
$array as $k => $v){
        if(
$key!=$k){
           
$holding[$k]=$v;
        }
    }   
    return
$holding;
}

$lunch = array('sandwich' => 'cheese', 'cookie'=>'oatmeal','drink' => 'tea','fruit' => 'apple');
echo
'<pre>';
print_r($lunch);
$lunch=arem($lunch,'apple');
print_r($lunch);
$lunch=akrem($lunch,'sandwich');
print_r($lunch);
echo
'</pre>';
?>

(remove 9's in email)
up
3
ted.devito at 9gmail9 dot 99com
16 years ago
based on worldclimb's arem(), here is a recursive array value removal tool that can work with multidimensional arrays.

function remove_from_array($array,$value){
    $clear = true;
    $holding=array();
  
    foreach($array as $k => $v){
        if (is_array($v)) {
            $holding [$k] = remove_from_array ($v, $value);
            }
        elseif ($value == $v) {
            $clear = false;
            }
        elseif($value != $v){
            $holding[$k]=$v; // removes an item by combing through the array in order and saving the good stuff
        }
    }  
    if ($clear) return $holding; // only pass back the holding array if we didn't find the value
}
up
10
developer at i-space dot org
22 years ago
remember that array_slice returns an array with the current element. you must use array_slice($array, $index+1) if you want to get the next elements.
up
6
s0i0m at dreamevilconcepts dot com
16 years ago
Using the varname function referenced from the array_search page, submitted by dcez at land dot ru. I created a multi-dimensional array splice function. It's usage is like so:

$array['admin'] = array('blah1', 'blah2');
$array['voice'] = array('blah3', 'blah4');
array_cut('blah4', $array);

...Would strip blah4 from the array, no matter where the position of it was in the array ^^ Returning this...

Array ( [admin] => Array ( [0] => blah1 [1] => blah2 ) [voice] => Array ( [0] => blah3 ) )

Here is the code...

<?php

 
function varname ($var)
  {
   
// varname function by dcez at land dot ru
   
return (isset($var)) ? array_search($var, $GLOBALS) : false;
  }

  function
array_cut($needle, $haystack)
  {
    foreach (
$haystack as $k => $v)
    {
      for (
$i=0; $i<count($v); $i++)
        if (
$v[$i] === $needle)
        {
          return
array_splice($GLOBALS[varname($haystack)][$k], $i, 1);
          break; break;
        }
    }

?>

Check out dreamevilconcept's forum for more innovative creations!
up
1
kansey
9 years ago
To save the sort order of a numeric index in the array. Version php =>5.5.26
/*
Example
*/

$arr = array( "1" =>2, "2" =>3 , "3" =>5 );

print_r(array_slice($arr,1,null,true));

/*
Result

Array
(
[2] => 3
[3] => 5
)
*/
up
1
Benjamin Sonntag
1 year ago
The documentation doesn't say it, but if LENGTH is ZERO, then the result is an empty array [].
up
0
xananax at yelostudio dot com
13 years ago
<?php
/**
* Reorders an array by keys according to a list of values.
* @param array $array the array to reorder. Passed by reference
* @param array $list the list to reorder by
* @param boolean $keepRest if set to FALSE, anything not in the $list array will be removed.
* @param boolean $prepend if set to TRUE, will prepend the remaining values instead of appending them
* @author xananax AT yelostudio DOT com
*/
function array_reorder(array &$array,array $list,$keepRest=TRUE,$prepend=FALSE,$preserveKeys=TRUE){
   
$temp = array();
    foreach(
$list as $i){
        if(isset(
$array[$i])){
           
$tempValue = array_slice(
               
$array,
               
array_search($i,array_keys($array)),
               
1,
               
$preserveKeys
           
);
           
$temp[$i] = array_shift($tempValue);
            unset(
$array[$i]);
        }
    }
   
$array = $keepRest ?
        (
$prepend?
           
$array+$temp
           
:$temp+$array
       
)
        :
$temp;
}

/** exemple ** /
$a = array(
    'a'    =>    'a',
    'b'    =>    'b',
    'c'    =>    'c',
    'd'    =>    'd',
    'e'    =>    'e'
);
$order = array('c','b','a');

array_reorder($a,$order,TRUE);
echo '<pre>';
print_r($a);
echo '</pre>';
/** exemple end **/
?>
up
0
andreasblixt (at) msn (dot) com
19 years ago
<?php
   
// Combines two arrays by inserting one into the other at a given position then returns the result
   
function array_insert($src, $dest, $pos) {
        if (!
is_array($src) || !is_array($dest) || $pos <= 0) return FALSE;
        return
array_merge(array_slice($dest, 0, $pos), $src, array_slice($dest, $pos));
    }
?>
up
-3
aexchecker at yahoo dot com
17 years ago
<?php
/**
* @desc
* Combines two arrays by inserting one into the other at a given position then
* returns the result.
*
* @since   2007/10/04
* @version v0.7 2007/10/04 18:47:52
* @author  AexChecker <AexChecker@yahoo.com>
* @param   array $source
* @param   array $destination
* @param   int [optional] $offset
* @param   int [optional] $length
* @return  array
*/
function array_insert($source, $destination, $offset = NULL, $length = NULL) {
    if (!
is_array($source) || empty($source)) {
        if (
is_array($destination) && !empty($destination)) {
            return
$destination;
        }
        return array();
    }
    if (
is_null($offset)) {
        return
array_merge($destination, $source);
    }
   
$offset = var2int($offset);
    if (
is_null($length)) {
        if (
$offset === 0) {
            return
array_merge($source, array_slice($destination, 1));
        }
        if (
$offset === -1) {
            return
array_merge(array_slice($destination, 0, -1), $source);
        }
        return
array_merge(
           
array_slice($destination, 0, $offset),
           
$source,
           
array_slice($destination, ++$offset)
        );
    }
    if (
$offset === 0) {
        return
array_merge($source, array_slice($destination, $length));
    }
   
$destination_count = count($destination);
   
$length = var2int($length);
    if (
$offset > 0) {
        if (
$destination_count - $offset < 1) {
            return
array_merge($destination, $source);
        }
    } else{
        if ((
$t = $destination_count + $offset) < 1) {
            return
array_merge($source, $destination);
        }
       
$offset = $t;
    }
    if (
$length > 0) {
       
$length+= $offset;
    } elseif (
$length < 0 && !($length * -1 < $destination_count)) {
        return
$source;
    } else {
       
$length = $offset;
    }
    return
array_merge(
       
array_slice($destination, 0, $offset),
       
$source,
       
array_slice($destination, $length)
    );
}
?>
up
-3
aflavio at gmail dot com
17 years ago
/**
    * Remove a value from a array
    * @param string $val
    * @param array $arr
    * @return array $array_remval
    */
    function array_remval($val, &$arr)
    {
          $array_remval = $arr;
          for($x=0;$x<count($array_remval);$x++)
          {
              $i=array_search($val,$array_remval);
              if (is_numeric($i)) {
                  $array_temp  = array_slice($array_remval, 0, $i );
                $array_temp2 = array_slice($array_remval, $i+1, count($array_remval)-1 );
                $array_remval = array_merge($array_temp, $array_temp2);
              }
          }
          return $array_remval;
    }

$stack=Array('apple','banana','pear','apple', 'cherry', 'apple');
array_remval("apple", $stack);

//output: Array('banana','pear', 'cherry')
up
-2
bishop
20 years ago
Sometimes you need to pick certain non-integer and/or non-sequential keys out of an array. Consider using the array_pick() implementation below to pull specific keys, in a specific order, out of a source array:

<?php

$a
= array ('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4);
$b = array_pick($a, array ('d', 'b'));

// now:
// $a = array ('a' => 1, 'c' => '3');
// $b = array ('d' => 4, 'b' => '2');

function &array_pick(&$array, $keys)
{
    if (!
is_array($array)) {
       
trigger_error('First parameter must be an array', E_USER_ERROR);
        return
false;
    }

    if (! (
is_array($keys) || is_scalar($keys))) {
       
trigger_error('Second parameter must be an array of keys or a scalar key', E_USER_ERROR);
        return
false;
    }

    if (
is_array($keys)) {
       
// nothing to do
   
} else if (is_scalar($keys)) {
       
$keys = array ($keys);
    }

   
$resultArray = array ();
    foreach (
$keys as $key) {
        if (
is_scalar($key)) {
            if (
array_key_exists($key, $array)) {
               
$resultArray[$key] = $array[$key];
                unset(
$array[$key]);
            }
        } else {
           
trigger_error('Supplied key is not scalar', E_USER_ERROR);
            return
false;
        }
    }

    return
$resultArray;
}

?>
up
-3
Mr. P
16 years ago
Note that offset is not the same thing as key. Offset always starts at 0, while keys might be any number.

So this:

<?php print_r(array_slice(array(0 => 0, 5 => 5, 13 => 13),1)); ?>

will result in this:
Array
(
    [0] => 5
    [1] => 13
)
up
-2
Anonymous
18 years ago
If you specify the fourth argument (to not reassign the keys), then there appears to be no way to get the function to return all values to the end of the array. Assigning -0 or NULL or just putting two commas in a row won't return any results.
up
-5
Nathan - thefiscster510 at gmail dot com
13 years ago
If you want to remove a specified entry from an array i made this mwethod...

<?php
$array
= array("Entry1","entry2","entry3");

$int = 3; //Number of entries in the array
$int2 = 0; //Starter array spot... it will begine its search at 0.
$del_num = 1; //Represents the second entry in the array... which is the one we will happen to remove this time... i.e. 0 = first entry, 1 = second entry, 2 = third...........

$newarray = array(); //Empty array that will be the new array minus the specified entry...
print_r($array) . "<br>";    //print original array contents
print_r($newarray). "<br>"; //print the new empty array

do
{
$user = $array[$int2];
$key = array_search($user, $array);
if (
$key == $del_num)
{

}
else
{
$newarray[] = $array[$int2];
}

$int2 = $int2 + 1;
} while (
$int2 < $int);

print_r($newarray). "<br>"; //print the new array

?>
up
-4
delew
13 years ago
just a little tip.
to preserve keys without providing length: use NULL

array_slice($array, $my_offset, NULL, true);
up
-6
jamon at clearsightdesign dot com
15 years ago
I was trying to find a good way to find the previous several and next several results from an array created in a MySQL query. I found that most MySQL solutions to this problem were complex. Here is a simple function that returns the previous and next rows from the array.

<?php

/*
** function array_surround by Jamon Holmgren of ClearSight Design
** Version 1.0 - 4/10/2009
** Please direct comments and questions to my first name at symbol clearsightdesign.com
**
** Returns an array with only the $before and $after number of results
** This is set to work best with MySQL data results
** Use this to find the rows immediately before and after a particular row, as many as you want
**
** Example usage:
**   $mysql_ar is an array of results from a MySQL query and the current id is $cur_id
**   We want to get the row before this one and five rows afterward
**
** $near_rows = array_surround($mysql_ar, "id", $cur_id, 1, 5)
**
**   Previous row is now $near_rows[-1]
**   Current row is now $near_rows[0]
**   Next row is $near_rows[1] ... etc
**   If there is no previous row, $near_rows[-1] will not be set...test for it with is_array($near_rows[-1])
**
*/
function array_surround($src_array, $field, $value, $before = 1, $after = 1) {
    if(
is_array($src_array)) {
       
// reset all the keys to 0 through whatever in case they aren't sequential
       
$new_array = array_values($src_array);
       
// now loop through and find the key in array that matches the criteria in $field and $value
       
foreach($new_array as $k => $s) {
            if(
$s[$field] == $value) {
               
// Found the one we wanted
               
$ck = $k; // put the key in the $ck (current key)
               
break;
            }
        }
        if(isset(
$ck)) { // Found it!
           
$result_start = $ck - $before; // Set the start key
           
$result_length = $before + 1 + $after; // Set the number of keys to return
           
if($result_start < 0) { // Oops, start key is before first result
               
$result_length = $result_length + $result_start; // Reduce the number of keys to return
               
$result_start = 0; // Set the start key to the first result
           
}
           
$result_temp = array_slice($new_array, $result_start, $result_length); // Slice out the results we want
            // Now we have an array, but we want array[-$before] to array[$after] not 0 to whatever.
           
foreach($result_temp as $rk => $rt) { // set all the keys to -$before to +$after
               
$result[$result_start - $ck + $rk] = $rt;
            }
            return
$result;
        } else {
// didn't find it!
           
return false;
        }
    } else {
// They didn't send an array
       
return false;
    }
}

?>

I hope you find this useful! I welcome constructive criticism or comments or of course praise ;) -- just e-mail me.

- Jamon Holmgren
up
-5
SomeGuy
8 years ago
Thank to taylorbarstow here the function with the unset feature.
<?php
function array_slice_assoc(&$array,$keys,$unset = true) {
   
$return = array_intersect_key($array, array_flip($keys));
    if (
$unset) {
        foreach (
$keys as $value) {
            unset(
$array[$value]);
        }
    }
    return
$return;
}
?>
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