Algorithm to separate pagination display by ...?

Question

Have an $A is the data for pagination:

   $A = array(
      0=>array(
          0=>1,
          1=>2
          ),
      1=>array(
          0=>3,
          1=>5,
          2=>2
        ),
      2=>array(
          0=>3,
          1=>1,
          2=>6,
          3=>6
          )
      );

Anybody could help me to get the expected ouput (output this "...." more) the most important ?

.... told that it is still more element need to display next page. or it the remain element from previous page.

There are 09 elements of $A to display ,So

I set

$show_per_page = 3;

Output (for the first page):

  1 
  2
Total:3
  3
 ....//output this "...."  more 

Output (for the second page):

....//output this "...." continue from first page 
  5
  2
Total:10
  3
.... //output this "...." more

Output (for the third page):

 .... //output this "...." continue from  second page
    1
    6
    6
    Total:16

if I set

$show_per_page = 5;

Output (for the first page):

1
2
Total:3
3
5
2
Total:10
// .... //not output this "...." more now 

Output (for the second page):

3
1
6
6
Total:16

if I set

$show_per_page = 9;

OUTPUT:

        1
        2
      Total:3         
         3
         5
         2
      Total:10
         3
         1
         6
         6
     Total:16

Currently I am try to do with the function paging_from_multi_arr but I am stuck on how implement to got the expeted result:

// page to show (1-indexed)
// number of items to show per page
function paging_from_multi_arr($display_array, $page){
    Global $show_per_page;
    $start = $show_per_page * ($page-1);
    $end   = $show_per_page * $page;
    $i = 0;
    foreach($display_array as $main_order=>$section){
        $total = 0;
        foreach($section as $sub_order=>$value){
            if($i >= $end){
                break 2; // break out of both loops
            }

            $total += $value;
            if($i >= $start){
                echo $value.'<br>';
            }
            $i++;
        }
        if($i >= $start){
            echo 'Total:'.$total.'<br>';
        }
        if($i >= $end){
            break;
        }
    }
    $total = count($display_array, COUNT_RECURSIVE);
    // Total numbers of elements in $display_array array.
    // See http://php.net/manual/en/function.count.php
    if ($end < $total){
        echo "...";
    }
}


$show_per_page = 5;
paging_from_multi_arr($A,$_GET["page"]);

Do you have any idea with the function here? Or could give the better algorithm?

thanks

Answer 1

This should give you the output you're looking for:

function flatten_display_array($display_array){
    $new_array = array();
    $count = 0;

    foreach($display_array as $main_order => $section){
        $total  = 0;
        foreach($section as $sub_order => $value){
            $new_array[] = array('main'  => $main_order,
                                 'sub'      => $sub_order,
                                 'value'    => $value);
            $total += $value;
            $count++;
        }
        // Add section's total to final element in section
        $new_array[$count-1]['total']   = $total;
    }

    return $new_array;
}

function paging_from_multi_array($display_array, $page = 1, $show_per_page = 3){
    if(isset($_GET['page']) && is_numeric($_GET['page'])){
        // Page number set externally
        $page = $_GET['page'];
    }
    if(isset($_GET['per_page']) && is_numeric($_GET['per_page'])){
        // Per page set externally
        $show_per_page  = $_GET['per_page'];
    }

    $start  = $show_per_page*($page-1);
    $end    = $show_per_page*$page;

    // Convert array to useable format
    $new_array = flatten_display_array($display_array);

    /* Formatting elements */
    $top_string = '....';   // Indicator continues is on previous page
    $bottom_string  = '....';   // Indicator continues on next page
    $br         = '<br />';     // Line break
    $indent     = '&nbsp;&nbsp;&nbsp;'; // Indent of value row

    $count  = 0;
    $string = '';

    for($i = $start; $i < $end; $i++){
        // Loop through visible range
        $string .= $indent.$new_array[$i]['value'].$br;
        if(isset($new_array[$i]['total'])){
            $string .= 'Total: '.$new_array[$i]['total'].$br;
        }
    }

    // Check previous page
    if($start > 0 && $start < count($new_array) && !isset($new_array[$start-1]['total'])){
        // Started mid-way through section
        $string = $top_string.$br.$string;
    }

    // Check next page
    if($end-1 < count($new_array) && !isset($new_array[$end-1]['total'])){
        // Stopped mid-way through section
        $string .= $bottom_string.$br;
    }

    return $string;
}

To use it, just call the paging_from_multi_array() function:

echo paging_from_multi_array($A);

This way, if the page number or the amount to show per page is not set, it will default to the ones set in the first line of paging_from_multi_array() (currently page 1 and 3 per page).

Also, look at the lines under /* Formatting Elements */ to set the elements for the output (eg: the '...' before and after each segment.

Answer 2

Without the "total" calculation, it should be a simple pagination (by merging the sub-arrays and paginate on the big array). But actually, "total" has nothing to do with the pagination itself. So I recommending let's first forget the "total" for paginating, then insert it in approriate place later.

My idea begins with creating a merge-array like this:

$B = array(
  0=>1,
  1=>2
  0=>3,
  1=>5,
  2=>2
  0=>3,
  1=>1,
  2=>6,
  3=>6
}

And another array to keep track of the beginning of each sub-array of $A in the merge-array $B:

$C = {0, 2, 5}

Then I can do the pagination pretty simply as usual. About the "total", we can use the original array A to calculate it, then insert into the approriate position based on C.

For a quick example, at page 2, max-per-page = 3 From B, I get the sub-array B1 : B(offset = 1, max-per-page=3, from B[3] to B[5])

$B1 = {
  1=>5,
  2=>2,
  0=>3
}

Based on $C={0,2,5}, by a simple "for" loop, we can have $C[1] = 2 < 3 < 5 = 5 = $C[2] < length(B), so at here we know that we will show 2 sub-array (A[1] and a[2]); and we must calculate and return total(A[1]) as well.

That's my idea. I think it would make things easier to keep track.