Repeat array with array_slice

Question

I just want to do one thing, I have an array with products, lets say like this (in simple way):

$products = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k');

I am outputing that products in a slider (showing 3 products), and I have arrows (left and right).

Primary I am on page 1 ($page = 0;), and using array_slice($products, $page * 3, 3);, so it will return:

array('a', 'b', 'c');

When I click arrow right, it will show:

array('d', 'e', 'f');

array('g', 'h', 'i');

array('j', 'k');

And here is the point and my question. I want on this page to return array('j', 'k', 'a');

How can I do it in the simpliest way?

PS: array with products is generated dynamically.

PPS: I also want to do it in other direction, ie. when I click left arrow, and I am on the first page, I want to return array('i', 'j', 'k');

Any ideas are appreciated.

Thanks a lot.

Amal · Accepted Answer · 2013-11-20 15:15:39Z

2

You can use array_slice() to get the required length from both ends of the array and then merge it with the original array, like so:

$lengthToExtend = 3;
$first = array_slice($products, 0, $lengthToExtend);
$last = array_slice($products, -$lengthToExtend, $lengthToExtend);
$products = array_merge($last, $products, $first);

Demo.

answered Nov 20, 2013 at 15:15

Amal

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2 Comments

Legionar Over a year ago

Thanks, now when I am thinking about that again, I can see the solution, like you wrote. But I am thinking, how it will be done, on next page, after array('j', 'k', 'a');... Then I will need to get array('b', 'c', 'd');, and so on...

Amal Over a year ago

@Legionar: Then just increase $lengthToExtend? (See demo)

ComFreek · Accepted Answer · 2013-11-20 15:23:51Z

2

My crazy solution:

<?php
$products = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k');

$perPage = 3;
$offset = 9;

if ($offset >= count($products)) $offset = 0;

$page = array_slice($products, $offset, $perPage);

if (count($products) <= ($offset+$perPage)) {
    $page = array_merge($page, array_slice($products, 0, $perPage - count($page)));
}

print_r($page);

Demo at Ideone.com

edited Nov 20, 2013 at 15:23

ComFreek

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answered Nov 20, 2013 at 15:22

Nikolay Krasnov

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2 Comments

Legionar Over a year ago

Are you sure, this will work? It doesnt look like - when you $offset = 0; it will cause a problem...

Nikolay Krasnov Over a year ago

Offset should be in 0..count($products) range, then it works fine

baldrs · Accepted Answer · 2013-11-20 15:52:19Z

2

All you need to know here is where to begin. The same way its done backwards by replacing reset with end and next with prev

<?php 

$a = array_map('chr', range(65,90));

$start = 22; 

# init
$i = 0; while($i < $start) { next($a); $i++; }

# for example, do this three times
for($j = 0; $j < 3; $j++)  { 
    $f = [];
    for($e = 0; $e < 3; $e++) {

      $c = current($a);

      if($c === false) {
        $c = reset($a);
      }

      $f[] = $c;

      next($a);

    }
    print_r($f);
}

DEMO

DEMO(backwards)

edited Nov 20, 2013 at 15:52

answered Nov 20, 2013 at 15:37

baldrs

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Comments

sectus · Accepted Answer · 2013-11-21 01:26:27Z

1

function getPortion($products, $page, $per_page)
    {
    $index = $page * $per_page;

    // to get always positive module
    $real_index = ($index % sizeof($products) + sizeof($products)) % sizeof($products);

    $return = array_slice($products, $real_index, $per_page);
    while (sizeof($return) < $per_page)
        {
        $return = array_merge($return, array_slice($products, 0, $per_page - sizeof($return)));
        }
    return $return;
    }

$products = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k');

// 0 page
echo json_encode(getPortion($products, 0, 3));
// ["a","b","c"]

// 3 page
echo json_encode(getPortion($products, 3, 3));
// ["j","k","a"]

// -1 page
echo json_encode(getPortion($products, -1, 3));
// ["i","j","k"]

// 0 page, but per_page larger than array length.
echo json_encode(getPortion(array('a', 'b', 'c'), 0, 5));
// ["a","b","c","a","b"]

Demo.

edited Nov 21, 2013 at 1:26

answered Nov 21, 2013 at 1:17

sectus

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1 Comment

Legionar Over a year ago

Excelent. The nicest solution. Thanks a lot!

Ninad Nagwekar · Accepted Answer · 2015-08-12 11:04:50Z

0

This is more simple, I guess... works perfect for me

$products = array_chunk($products, $limit, true); // true if you want keep keys
$products_sliced = $products[$page-1];

answered Aug 12, 2015 at 11:04

Ninad Nagwekar

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1 Comment

Legionar Over a year ago

This will of course not work... When on the last page, it will not return array('j', 'k', 'a');...

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