array_chunk

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

array_chunk — Divide un array en fragmentos

Descripción

array_chunk(array $array, int $size, bool $preserve_keys = false): array

Divide un array en arrays con elementos del tamaño definido en size. El último fragmento puede contener menos elementos que size.

Parámetros

array: Array para trabajar en
size: El tamaño de cada fragmento.
preserve_keys: Cuando se establece en true las keys serán preservadas. El valor por defecto es false lo cual reindexará los fragmentos numéricamente.

Valores devueltos

Retorna un array multidimensional indexado numéricamente, comenzando desde cero, en el cual cada dimensión contiene la cantidad de elementos definida en size.

Errores/Excepciones

Si size es inferior a 1, una E_WARNING será arrojada y null será retornado.

Ejemplos

Ejemplo #1 Ejemplo de array_chunk()

<?php
$input_array = array('a', 'b', 'c', 'd', 'e');
print_r(array_chunk($input_array, 2));
print_r(array_chunk($input_array, 2, true));
?>

El resultado del ejemplo sería:

Array
(
    [0] => Array
        (
            [0] => a
            [1] => b
        )

    [1] => Array
        (
            [0] => c
            [1] => d
        )

    [2] => Array
        (
            [0] => e
        )

)
Array
(
    [0] => Array
        (
            [0] => a
            [1] => b
        )

    [1] => Array
        (
            [2] => c
            [3] => d
        )

    [2] => Array
        (
            [4] => e
        )

)

Ver también

array_slice() - Extraer una parte de un array

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User Contributed Notes 19 notes

down

azspot at gmail dot com ¶

17 years ago

Tried to use an example below (#56022) for array_chunk_fixed that would "partition" or divide an array into a desired number of split lists -- a useful procedure for "chunking" up objects or text items into columns, or partitioning any type of data resource. However, there seems to be a flaw with array_chunk_fixed — for instance, try it with a nine item list and with four partitions. It results in 3 entries with 3 items, then a blank array.

So, here is the output of my own dabbling on the matter:

<?php

function partition( $list, $p ) {
    $listlen = count( $list );
    $partlen = floor( $listlen / $p );
    $partrem = $listlen % $p;
    $partition = array();
    $mark = 0;
    for ($px = 0; $px < $p; $px++) {
        $incr = ($px < $partrem) ? $partlen + 1 : $partlen;
        $partition[$px] = array_slice( $list, $mark, $incr );
        $mark += $incr;
    }
    return $partition;
}

$citylist = array( "Black Canyon City", "Chandler", "Flagstaff", "Gilbert", "Glendale", "Globe", "Mesa", "Miami",
                   "Phoenix", "Peoria", "Prescott", "Scottsdale", "Sun City", "Surprise", "Tempe", "Tucson", "Wickenburg" );
print_r( partition( $citylist, 3 ) );

?>

Array
(
    [0] => Array
        (
            [0] => Black Canyon City
            [1] => Chandler
            [2] => Flagstaff
            [3] => Gilbert
            [4] => Glendale
            [5] => Globe
        )

    [1] => Array
        (
            [0] => Mesa
            [1] => Miami
            [2] => Phoenix
            [3] => Peoria
            [4] => Prescott
            [5] => Scottsdale
        )

    [2] => Array
        (
            [0] => Sun City
            [1] => Surprise
            [2] => Tempe
            [3] => Tucson
            [4] => Wickenburg
        )

)

down

Andrew Martin ¶

6 years ago

To reverse an array_chunk, use array_merge, passing the chunks as a variadic:

<?php
$array = [1, 2, 3, 4, 5, 6, 7, 8, 9];

$chunks = array_chunk($array, 3);
// $chunks = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

$de_chunked = array_merge(…$chunks);
// $de_chunked = [1, 2, 3, 4, 5, 6, 7, 8, 9]
?>

down

dustin at fivetechnology dot com ¶

8 years ago

Had need to chunk an object which implemented ArrayAccess Iterator Countable.  array_chunk wouldn't do it.  Should work for any list of things

<?php
   $listOfThings = array(1,2,3,4,5,6,7,8,9,10,11,12,13);
   print_r(chunk_iterable($listOfThings, 4);

  function chunk_iterable($listOfThings, $size) {
      $chunk = 0;
      $chunks = array_fill(0, ceil(count($listOfThings) / $size) - 1, array());
      $index = 0;
      foreach($listOfThings as $thing) {
        if ($index && $index % $size == 0) $chunk++;
        $chunks[$chunk][] = $thing;
        $index++;
      }
      return $chunks;
  }
?>

down

suisuiruyi at aliyun dot com ¶

8 years ago

chunk array vertically

$arr    = range(1, 19);
function array_chunk_vertical($arr, $percolnum){
    $n = count($arr);
    $mod    = $n % $percolnum;
    $cols   = floor($n / $percolnum);
    $mod ? $cols++ : null ;
    $re     = array();
    for($col = 0; $col < $cols; $col++){
        for($row = 0; $row < $percolnum; $row++){
            if($arr){
                $re[$row][]   = array_shift($arr);
            }
        }
    }
    return $re;
}
$result = array_chunk_vertical($arr, 6);
foreach($result  as $row){
    foreach($row as $val){
        echo '['.$val.']';
    }
    echo '<br/>';
}
/*
[1][7][13][19]
[2][8][14]
[3][9][15]
[4][10][16]
[5][11][17]
[6][12][18]
 */

down

Anonymous ¶

3 years ago

Most easy way split array to parts

<?php

$arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

print_r(array_chunk($arr, ceil(count($arr) / 2)));
// return: [[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]]

print_r(array_chunk($arr, ceil(count($arr) / 3)));
// return: [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10]]

?>

down

nate at ruggfamily dot com ¶

14 years ago

If you just want to grab one chunk from an array, you should use array_slice().

down

Anonymous ¶

18 years ago

Here my array_chunk_values( ) with values distributed by lines (columns are balanced as much as possible) :

<?php
    function array_chunk_vertical($data, $columns) {
        $n = count($data) ;
        $per_column = floor($n / $columns) ;
        $rest = $n % $columns ;

        // The map
        $per_columns = array( ) ;
        for ( $i = 0 ; $i < $columns ; $i++ ) {
            $per_columns[$i] = $per_column + ($i < $rest ? 1 : 0) ;
        }

        $tabular = array( ) ;
        foreach ( $per_columns as $rows ) {
            for ( $i = 0 ; $i < $rows ; $i++ ) {
                $tabular[$i][ ] = array_shift($data) ;
            }
        }

        return $tabular ;
    }

    header('Content-Type: text/plain') ;

    $data = array_chunk_vertical(range(1, 31), 7) ;
    foreach ( $data as $row ) {
        foreach ( $row as $value ) {
            printf('[%2s]', $value) ;
        }
        echo "\r\n" ;
    }

    /*
        Output :

        [ 1][ 6][11][16][20][24][28]
        [ 2][ 7][12][17][21][25][29]
        [ 3][ 8][13][18][22][26][30]
        [ 4][ 9][14][19][23][27][31]
        [ 5][10][15]
    */
?>

down

OIS ¶

16 years ago

Response to azspot at gmail dot com function partition.

$columns = 3;
$citylist = array('Black Canyon City', 'Chandler', 'Flagstaff', 'Gilbert', 'Glendale', 'Globe', 'Mesa', 'Miami', 'Phoenix', 'Peoria', 'Prescott', 'Scottsdale', 'Sun City', 'Surprise', 'Tempe', 'Tucson', 'Wickenburg');
print_r(array_chunk($citylist, ceil(count($citylist) / $columns)));

Output:
Array
(
    [0] => Array
        (
            [0] => Black Canyon City
            [1] => Chandler
            [2] => Flagstaff
            [3] => Gilbert
            [4] => Glendale
            [5] => Globe
        )

    [1] => Array
        (
            [0] => Mesa
            [1] => Miami
            [2] => Phoenix
            [3] => Peoria
            [4] => Prescott
            [5] => Scottsdale
        )

    [2] => Array
        (
            [0] => Sun City
            [1] => Surprise
            [2] => Tempe
            [3] => Tucson
            [4] => Wickenburg
        )

)

down

siddharthundare at gmail dot com ¶

9 years ago

<table>
<tr>
<?php

$array_chunkdata = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25);
$chunk  = array_chunk($array_chunkdata,5);
$rev_counter = 2;

function for_chunk($chunk_data){

    echo "<td><table>";

      foreach($chunk_data as $key => $chunk_value)
      {
        echo "<tr><td>";
        echo $chunk_value;
        echo "</td></tr>";
      }
      echo "</table></td>";   

}

foreach($chunk as $key => $chunk_data)
{
    if($rev_counter%2==0)
    {   
      for_chunk($chunk_data);
    }
    else
    {
      $chunk_data =  array_reverse($chunk_data);
      
      for_chunk($chunk_data);
     
    } 
  $rev_counter++;
}
?> 
</tr>
</table>
/*
Output:
1
2
3
4
5
    
10
9
8
7
6
    
11
12
13
14
15
    
20
19
18
17
16
    
21
22
23
24
25
*/

down

phpm at nreynolds dot me dot uk ¶

20 years ago

array_chunk() is helpful when constructing tables with a known number of columns but an unknown number of values, such as a calendar month. Example:

<?php

$values = range(1, 31);
$rows = array_chunk($values, 7);

print "<table>\n";
foreach ($rows as $row) {
    print "<tr>\n";
    foreach ($row as $value) {
        print "<td>" . $value . "</td>\n";
    }
    print "</tr>\n";
}
print "</table>\n";

?>

Outputs:

1 2 3 4 5 6 7 
8 9 10 11 12 13 14 
15 16 17 18 19 20 21 
22 23 24 25 26 27 28 
29 30 31 

The other direction is possible too, with the aid of a function included at the bottom of this note. Changing this line:
  $rows = array_chunk($values, 7);

To this:
  $rows = array_chunk_vertical($values, 7);

Produces a vertical calendar with seven columns:

1 6  11 16 21 26 31 
2 7  12 17 22 27 
3 8  13 18 23 28 
4 9  14 19 24 29 
5 10 15 20 25 30 

You can also specify that $size refers to the number of rows, not columns:
  $rows = array_chunk_vertical($values, 7, false, false);

Producing this:

1 8  15 22 29 
2 9  16 23 30 
3 10 17 24 31 
4 11 18 25 
5 12 19 26 
6 13 20 27 
7 14 21 28 

The function:

<?php

function array_chunk_vertical($input, $size, $preserve_keys = false, $size_is_horizontal = true)
{
    $chunks = array();
    
    if ($size_is_horizontal) {
        $chunk_count = ceil(count($input) / $size);
    } else {
        $chunk_count = $size;
    }
    
    for ($chunk_index = 0; $chunk_index < $chunk_count; $chunk_index++) {
        $chunks[] = array();
    }

    $chunk_index = 0;
    foreach ($input as $key => $value)
    {
        if ($preserve_keys) {
            $chunks[$chunk_index][$key] = $value;
        } else {
            $chunks[$chunk_index][] = $value;
        }
        
        if (++$chunk_index == $chunk_count) {
            $chunk_index = 0;
        }
    }
    
    return $chunks;
}

?>

down

mick at vandermostvanspijk dot nl ¶

20 years ago

[Editors note: This function was based on a previous function by gphemsley at nospam users dot sourceforge.net]



For those of you that need array_chunk() for PHP < 4.2.0, this function should do the trick:



<?php

if (!function_exists('array_chunk')) {

    function array_chunk( $input, $size, $preserve_keys = false) {

        @reset( $input );

        

        $i = $j = 0;



        while( @list( $key, $value ) = @each( $input ) ) {

            if( !( isset( $chunks[$i] ) ) ) {

               $chunks[$i] = array();

            }



            if( count( $chunks[$i] ) < $size ) {

                if( $preserve_keys ) {

                    $chunks[$i][$key] = $value;

                    $j++;

                } else {

                    $chunks[$i][] = $value;

                }

            } else {

                $i++;



                if( $preserve_keys ) {

                    $chunks[$i][$key] = $value;

                    $j++;

                } else {

                    $j = 0;

                    $chunks[$i][$j] = $value;

                }

            }

        }



        return $chunks;

    }

}

?>

down

dead dot screamer at seznam dot cz ¶

15 years ago

This function can be used to reverse effect of <?php array_Chunk()?>.
<?php
function array_Unchunk($array)
{
    return call_User_Func_Array('array_Merge',$array);
}

header('Content-Type: text/plain');
$array=array(
    array(
            'Black Canyon City',
            'Chandler',
            'Flagstaff',
            'Gilbert',
            'Glendale',
            'Globe',
    ),
    array(
            'Mesa',
            'Miami',
            'Phoenix',
            'Peoria',
            'Prescott',
            'Scottsdale',
    ),
    array(
            'Sun City',
            'Surprise',
            'Tempe',
            'Tucson',
            'Wickenburg',
    ),
);
var_Dump(array_Unchunk($array));
?>

Output:
array(17) {
  [0]=>
  string(17) "Black Canyon City"
  [1]=>
  string(8) "Chandler"
  [2]=>
  string(9) "Flagstaff"
  [3]=>
  string(7) "Gilbert"
  [4]=>
  string(8) "Glendale"
  [5]=>
  string(5) "Globe"
  [6]=>
  string(4) "Mesa"
  [7]=>
  string(5) "Miami"
  [8]=>
  string(7) "Phoenix"
  [9]=>
  string(6) "Peoria"
  [10]=>
  string(8) "Prescott"
  [11]=>
  string(10) "Scottsdale"
  [12]=>
  string(8) "Sun City"
  [13]=>
  string(8) "Surprise"
  [14]=>
  string(5) "Tempe"
  [15]=>
  string(6) "Tucson"
  [16]=>
  string(10) "Wickenburg"
}

down

stratboy ¶

11 years ago

Hi, I've made  a function to split an array into chunks based on columns wanted. For example:

<?php $a = array(1,2,3,4,5,6,7,8); ?>

goal (say, for 3 columns):

<?php
array(
   array(1,2,3),
   array(4,5,6),
   array(7,8)
);
?>

<?php
function get_array_columns($array, $columns){
        
        $columns_map = array();
        for($i=0; $i<$columns; $i++){ $columns_map[] = 0; }//init columns
        
        //create map
        $count = count($array);
        $position = 0;
        while($count > 0){
            $columns_map[$position]++;
            $position = ($position < $columns-1) ? ++$position : 0;
            $count--;
        }

        //chunk the array based on map
        $chunked = array();
        foreach($columns_map as $map){
            $chunked[] = array_splice($array,0,$map);
        }
        
        return $chunked;
    }//end get_array_columns
?>

down

leon at valkenb dot org ¶

3 years ago

With no luck finding a function; here is the one I wrote:
It will evenly distribute items into a fixed amount of groups but also keeps items that were sorted close together to be in the same output groups.
<?php
function distributed_array_chunk(array $items, int $groups, bool $preserveKeys = false) {

    $grouped = [];
    $groupsPerItem = $groups /  count($items);
    $progress = 0.00;

    foreach ($items as $key => $value) {

        $index = floor($progress += $groupsPerItem);

        if ($preserveKeys) {
            $grouped[$index][$key] = $value;
        }
        else{
            $grouped[$index][] = $value;
        }    
    }

    return $grouped;
}
?>

down

magick dit crow ot gmail dit com ¶

19 years ago

This function takes each few elements of an array and averages them together. It then places the averages in a new array. It is used to smooth out data. For example lets say you have a years worth of hit data to a site and you want to graph it by the week. Then use a bucket of 7 and graph the functions output.

function array_bucket($array, $bucket_size)  // bucket filter
{
    if (!is_array($array)) return false; // no empty arrays
    $buckets=array_chunk($array,$bucket_size);  // chop up array into bucket size units
    foreach ($buckets as $bucket) $new_array[key($buckets])=array_sum($bucket)/count($bucket);
    return $new_array;  // return new smooth array
}

down

normiridium at gmail dot com ¶

8 years ago

A breakdown by groups with excess:

function array_chunk_greedy($arr, $count){
    $arr = array_chunk($arr, $count);
    if(($k = count($arr)-1) > 0){    
        if(count($arr[$k]) < $count){
            $arr[$k-1] = array_merge($arr[$k-1], $arr[$k]);
            unset($arr[$k]);
        }            
    }
    return $arr;    
}

$arr = range(1, 13);
$arr = array_chunk_greedy($arr, 4);

print_r($arr);

[1,2,3,4,5,6,7,8,9,10,11,12,13] —> [1,2,3,4] [5,6,7,8] [9,10,11,12,13]

More examples:

[1,2,3,4,5,6,7,8,9,10,11,12] —> [1,2,3,4] [5,6,7,8] [9,10,11,12]
[1,2,3,4,5,6,7,8,9,10,11,12,13] —> [1,2,3,4] [5,6,7,8] [9,10,11,12,13]
[1,2,3,4,5,6,7,8,9,10,11,12,13,14] —> [1,2,3,4] [5,6,7,8] [9,10,11,12,13,14]
[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15] —> [1,2,3,4] [5,6,7,8] [9,10,11,12,13,14,15]
[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] —> [1,2,3,4] [5,6,7,8] [9,10,11,12] [13,14,15,16]

Example report:

$arr = range(1, 45);
$arr = array_chunk_lazy($arr, 10);

$arr = array_map(function($sub_value) {
            return implode('<br>', $sub_value);
        }, $arr);

$title = '<h2>title</h2>';
$arr = $title.implode($title, $arr).$title;

echo $arr;

down

webmaster at cafe-clope dot net ¶

19 years ago

based on the same syntax, useful about making columns :

<?php
function array_chunk_fixed($input, $num, $preserve_keys = FALSE) {
    $count = count($input) ;
    if($count)
        $input = array_chunk($input, ceil($count/$num), $preserve_keys) ;
    $input = array_pad($input, $num, array()) ;
    return $input ;
}

$array = array(1, 2, 3, 4, 5) ;
print_r(array_chunk($array, 2)) ;
print_r(array_chunk_fixed($array, 2)) ;
?>

---- array_chunk : fixed number of sub-items ----
Array(
    [0] => Array(
            [0] => 1
            [1] => 2
        )
    [1] => Array(
            [0] => 3
            [1] => 4
        )

    [2] => Array(
            [0] => 5
        )
)

---- array_chunk : fixed number of columns ----
Array(
    [0] => Array(
            [0] => 1
            [1] => 2
            [2] => 3
        )
    [1] => Array(
            [0] => 4
            [1] => 5
        )
)

down

-2

magick dit crow ot gmail dit com ¶

19 years ago

Mistake key did not do what I thought. A patch.

function array_bucket($array,$bucket_size)// bucket filter
{
    if (!is_array($array)) return false;
    $buckets=array_chunk($array,$bucket_size);// chop up array into bucket size units
    $I=0;
    foreach ($buckets as $bucket)
    {
        $new_array[$I++]=array_sum($bucket)/count($bucket);
    }
    return $new_array;// return new array
}

down

-5

Anonymous ¶

10 years ago

Couldn't get the array_chunk_values() working, so ended up with this implementation:

<?php
function array_chunk_columns($data, $num_columns) {
  $n = count($data);
  $per_column = floor($n / $num_columns);
  $rest = $n % $num_columns;

  $columns = array();
  $index = 0;
  for ($i = 0; $i < $num_columns; $i++) {
    // Add an extra item to each column while the column number is less than the
    // remainder.
    $add_rest = ($rest && ($i < $rest)) ? 1 : 0;
    $number = $per_column + $add_rest;
    $columns[] = array_slice($data, $index, $number);
    $index += $number;
  }

  return $columns;
}

?>

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