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
)
)
array_chunk
(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
array_chunk — Split an array into chunks
Description
Chunks an array into arrays with length elements.
The last chunk may contain less than length elements.
Parameters
-
array -
The array to work on
-
length -
The size of each chunk
-
preserve_keys -
When set to
truekeys will be preserved. Default isfalsewhich will reindex the chunk numerically
Return Values
Returns a multidimensional numerically indexed array, starting with zero,
with each dimension containing length elements.
Errors/Exceptions
If length is less than 1,
a ValueError will be thrown.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
If length is less than 1,
a ValueError will be thrown now;
previously, an error of level E_WARNING
has been raised instead, and the function returned null.
|
Examples
Example #1 array_chunk() example
<?php
$input_array = array('a', 'b', 'c', 'd', 'e');
print_r(array_chunk($input_array, 2));
print_r(array_chunk($input_array, 2, true));
?>The above example will output:
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
)
)
add a note
User Contributed Notes 20 notes
azspot at gmail dot com ¶
17 years ago
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]
?>
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]
*/
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]
*/
?>
nate at ruggfamily dot com ¶
14 years ago
If you just want to grab one chunk from an array, you should use array_slice().
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;
}
?>
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
*/
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]]
?>
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
)
)
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;
}
?>
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
?>
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 $chunks;
}
}
?>
dead dot screamer at seznam dot cz ¶
15 years ago
This function can be used to reverse effect of <?php array_Chunk()?>.
<?php
function array_Unchunk($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"
}
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 $new_array; // return new smooth array
}
normiridium at gmail dot com ¶
8 years ago
A breakdown by groups with excess:
function array_chunk_greedy($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;
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 $grouped;
}
?>
webmaster at cafe-clope dot net ¶
19 years ago
based on the same syntax, useful about making columns :
<?php
function array_chunk_fixed($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($array, 2)) ;
?>
---- array_chunk : fixed number of sub-items ----
Array(
[0] => Array(
[0] => 1
[1] => 2
)
[1] => Array(
[0] => 3
[1] => 4
)
[2] => Array(
[0] => 5
)
)
---- array_chunk : fixed number of columns ----
Array(
[0] => Array(
[0] => 1
[1] => 2
[2] => 3
)
[1] => Array(
[0] => 4
[1] => 5
)
)
magick dit crow ot gmail dit com ¶
19 years ago
Mistake key did not do what I thought. A patch.
function array_bucket($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 $new_array;// return new array
}
Anonymous ¶
10 years ago
Couldn't get the array_chunk_values() working, so ended up with this implementation:
<?php
function array_chunk_columns($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 $columns;
}
?>
Rasmus Schultz (http://mindplay.dk) ¶
15 years ago
Unfortunately, this function only accepts real arrays, not iterable objects... For that, you need this function:
<?php
function break_array($array, $page_size) {
$arrays = array();
$i = 0;
foreach ($array as $index => $item) {
if ($i++ % $page_size == 0) {
$arrays[] = array();
$current = & $arrays[count($arrays)-1];
}
$current[] = $item;
}
return $arrays;
}
?>
