PHP : Array Slice issue

Question

I'm having a small issue in php and i know the solution is straightforward but i can't seem to get around to it.

basically i have an array and i need small slices of it until the end.

<?php

$main = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15);
$start = 5;

$sliced = array_slice($main, $start);

$offset=3;


$startx = $start;

foreach($sliced as $s)
{

    $start_pt = $startx-$offset;
    $end_pt = ($startx) - count($main);

    $sli = array_slice($main,$start_pt,$end_pt+1);

    print_r($sli);
    echo "<br>##############################<br>";

    $startx++;
}

The above kinda works except for the last array which return blank since the length is now -1 or -0. It's taking it as length instead of offset.

Any easier/better way to do the above?

Result :

Array ( [0] => 3 [1] => 4 [2] => 5 [3] => 6 )
##############################
Array ( [0] => 4 [1] => 5 [2] => 6 [3] => 7 )
##############################
Array ( [0] => 5 [1] => 6 [2] => 7 [3] => 8 )
##############################
Array ( [0] => 6 [1] => 7 [2] => 8 [3] => 9 )
##############################
Array ( [0] => 7 [1] => 8 [2] => 9 [3] => 10 )
##############################
Array ( [0] => 8 [1] => 9 [2] => 10 [3] => 11 )
##############################
Array ( [0] => 9 [1] => 10 [2] => 11 [3] => 12 )
##############################
Array ( [0] => 10 [1] => 11 [2] => 12 [3] => 13 )
##############################
Array ( [0] => 11 [1] => 12 [2] => 13 [3] => 14 )
##############################
Array ( )
##############################

Answer 1

I think your purpose is to make overlapping ranges of same length from your array so you can try this:

<?php
$main = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15);

function overlapped_chunks($array,$start,$length,$overlap=False){
    if(!is_array($array)||!is_int($start)||!is_int($length))
        return;
    $go=false;
    $range=[];
    for($i=0;false!==key($array)&&NULL!==key($array);$i++){
        $temp=[];
        list(,$value)=each($array);
        if($i===$start){
            $go=true;
        }
        if($go){
            $range[]=$value;
        }
        if(count($range)===$length){
            $temp=$range;
            $range=array_slice($range,$length-(is_int($overlap)&&$overlap<$length&&$overlap>=0?$overlap:$length-($length-1)));
            yield $temp;
        }   
    }

    if($value!==end($temp)) yield $range;
}



foreach(overlapped_chunks($main,2,4,3) as $k=>$v){
     print_r($v);
    echo "<br>##############################<br>";


}

?>

and this will print

    Array ( [0] => 3 [1] => 4 [2] => 5 [3] => 6 ) 
##############################
Array ( [0] => 4 [1] => 5 [2] => 6 [3] => 7 ) 
##############################
Array ( [0] => 5 [1] => 6 [2] => 7 [3] => 8 ) 
##############################
Array ( [0] => 6 [1] => 7 [2] => 8 [3] => 9 ) 
##############################
Array ( [0] => 7 [1] => 8 [2] => 9 [3] => 10 ) 
##############################
Array ( [0] => 8 [1] => 9 [2] => 10 [3] => 11 ) 
##############################
Array ( [0] => 9 [1] => 10 [2] => 11 [3] => 12 ) 
##############################
Array ( [0] => 10 [1] => 11 [2] => 12 [3] => 13 ) 
##############################
Array ( [0] => 11 [1] => 12 [2] => 13 [3] => 14 ) 
##############################
Array ( [0] => 12 [1] => 13 [2] => 14 [3] => 15 ) 
##############################

It works with both ordered and associative arrays

Answer 2

What you want to do you can easily do with array_slice() and array_chunk()

first you need to slice array for offset and then split into chunks

<?php

$arr = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16);
$offset = 3;
$start = 5;

$splitedArr = array_slice($arr, $start);

for ($i = 0, $size = floor(count($splitedArr) / $offset); $i < $size; $i += $offset) {
  $sli = array_chunk($splitedArr, $offset);
  print_r($sli); 
}

So what it does it loops through array which was sliced for your first offset then it counts how many times it should iterate size of an array / size of a chunk and on each iteration adds the size of chunk. Inside the loop it actually makes chunk and prints it.

Output:

Array
(
    [0] => Array
        (
            [0] => 6
            [1] => 7
            [2] => 8
        )

    [1] => Array
        (
            [0] => 9
            [1] => 10
            [2] => 11
        )

    [2] => Array
        (
            [0] => 12
            [1] => 13
            [2] => 14
        )

    [3] => Array
        (
            [0] => 15
            [1] => 17
        )

)