Split array into chunks of alternating sizes - php

Question

I have an array:
Array
(
[0] => 0
[1] => 1
[2] => 2
[3] => 3
[4] => 4
[5] => 5
[6] => 6
[7] => 7
[8] => 8
[9] => 9
)
I want to split the array into alternating chunks. (size 2 then 3 then 2 then 3 etc)
Array
(
[0] => Array
(
[0] => 0
[1] => 1
[2] => 2
)
[1] => Array
(
[0] => 3
[1] => 4
)
[2] => Array
(
[0] => 5
[1] => 6
[2] => 7
)
[3] => Array
(
[0] => 8
[1] => 9
)
)

Answer 1

That should work:
$a = array(0 => 0,1 => 1,2 => 2,3 => 3,4 => 4, 5 => 5, 6 => 6,7 => 7,8 => 8,9 => 9);
$chunks = array();
$i=1;
while(count($a)){
$chunks[] = array_splice($a, 0,(2+($i%2)),array());
$i++;
}
echo "<pre>";
var_dump($chunks);

Answer 2

You can use array_splice for splitting the array, but you need to set conditions right? On what basis do you wanna split them?
And you can use array_merge to bring them back into an array of arrays.
In case of your current code, the code will be:
PHP Code
<?php
$array = array(0,1,2,3,4,5,6,7,8,9);
$final = array(
array_splice($array, 0, 3),
array_splice($array, 1, 2),
array_splice($array, 1, 2),
array_splice($array, 1, 2),
);
print_r($final);
?>
Output
Array
(
[0] => Array
(
[0] => 0
[1] => 1
[2] => 2
)
[1] => Array
(
[0] => 4
[1] => 5
)
[2] => Array
(
[0] => 6
[1] => 7
)
[3] => Array
(
[0] => 8
[1] => 9
)
)
Fiddle here: http://codepad.org/JzxcZ2Q1

Answer 3

Iterated calls of array_splice() seems like a great way to go. Here is a cleaner version of István Őri's answer. Subtracting from 5 removes the need to use the modulus operator.
Code: (Demo)
$array = range(1, 10);
$chunks = [];
$chunkSize = 3;
while ($array) {
$chunkSize = 5 - $chunkSize;
$chunks[] = array_splice($array, 0, $chunkSize);
}
var_export($chunks);
This snippet modifies $array as it iterates. array_splice() keeps removing elements from the front of the array. Eventually the array will become empty and the while() condition will fail -- breaking the loop.

Answer 4

You could use this, it isn't the most elegant, but it will just do the trick for you - and you can modify it nicely and adapt it to suit your purposes further:
<?php
$originalArray = array(0,1,2,3,4,5,6,7,8,9);
$counter=count($originalArray);
$isTwo=true;
$newArray=array();
$arrElement=0;
$i=0;
while($i<$counter)
{
if($isTwo)
{
$newArray[$arrElement]= array();
for($j=0; $j<2; $j++)
{
$newArray[$arrElement][$j]=$originalArray[$i+$j];
}
$i+=2;
$isTwo=false;
$arrElement++;
}
else
{
$newArray[$arrElement]= array();
for($j=0; $j<3; $j++)
{
$newArray[$arrElement][$j]=$originalArray[$i+$j];
}
$i+=3;
$isTwo=true;
$arrElement++;
}
}
var_dump($newArray);
?>
Output:
array(4) {
[0]=>
array(2) {
[0]=>
int(0)
[1]=>
int(1)
}
[1]=>
array(3) {
[0]=>
int(2)
[1]=>
int(3)
[2]=>
int(4)
}
[2]=>
array(2) {
[0]=>
int(5)
[1]=>
int(6)
}
[3]=>
array(3) {
[0]=>
int(7)
[1]=>
int(8)
[2]=>
int(9)
}
}

Answer 5

$tobechunked_arr = array(0,1,2,3,4,5,6,7,8,9);
$chunk_size_arr = array(3,2,3,2);
$j = 0;
foreach($chunk_size_arr as $key => $val)
{
for($i = 0; $i < $val; $i++)
{
$result_arr[$key][] = $tobechunked_arr[$j];
$j++;
}
}
echo "<pre>";
print_r($result_arr);

Answer 6

try this
<?php
$input_array = array('a', 'b', 'c', 'd', 'e');
print_r(array_chunk($input_array, 2));
print_r(array_chunk($input_array, 2, true));
?>
Update
<?php
$myArray = array("abc","def","ghi","jkl","mno","pqr","stu","vwx","yz");
$newArray = array_chunk($myArray, 2, false);
// Now process the multidimensional array made from array_chunk()
$i = 0;
foreach ($newArray as $inner_array) {
$i++;
echo "<h2>Chunk $i</h2>";
while (list($key, $value) = each($inner_array)) {
echo "$key: $value <br />";
}
}
?>
Output
Chunk 1
0: abc
1: def
Chunk 2
0: ghi
1: jkl
Chunk 3
0: mno
1: pqr
Chunk 4
0: stu
1: vwx
Chunk 5
0: yz