array_chunk()

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

将一个数组分割成多个

说明

将一个数组分割成多个数组，其中每个数组的单元数目由$size决定。最后一个数组的单元数目可能会少于$size个。

参数

需要操作的数组

每个数组的单元数目

设为TRUE，可以使 PHP 保留输入数组中原来的键名。如果你指定了FALSE，那每个结果数组将用从零开始的新数字索引。默认值是FALSE。

返回值

得到的数组是一个多维数组中的单元，其索引从零开始，每一维包含了$size个元素。

错误／异常

如果$size小于 1，会抛出一个E_WARNING错误并返回NULL。

范例

Example #1array_chunk()例子

以上例程会输出：

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
        )
)

参见

• array_slice() 从数组中取出一段

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:

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
    )
)

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

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 ';
}
/*
[1][7][13][19]
[2][8][14]
[3][9][15]
[4][10][16]
[5][11][17]
[6][12][18]
 */

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
    )
)

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

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

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
}

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:

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: 

[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 
based on the same syntax, useful about making columns :

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

goal (say, for 3 columns): 
This function can be used to reverse effect of .

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"
}
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])  [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('
', $sub_value);
    }, $arr);
$title = '
title
';
$arr = $title.implode($title, $arr).$title;
echo $arr;
Had need to chunk an object which implemented ArrayAccess Iterator Countable. array_chunk wouldn't do it. Should work for any list of things

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