Algorithm to separate pagination display by ...? - php

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 = ' '; // 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.