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August 29, 2015 13:57
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You have ... | |
[1,2,3,4,5,6,7,8,9] | |
[1,2,3,4,5,6,7] | |
[1,2,3] | |
You want in chunks of N (say 3) | |
[ | |
[1,2,3], | |
[4,5,6], | |
[7,8,9], | |
[1,2,3], | |
[4,5,6], | |
[7,1,2], | |
[3] | |
] |
<?php
/**
* Here, we just make some fake data. 1000 arrays filled with a random
* number of URLs.
*/
$urls_to_split_up = array();
for ($i = 0; $i < 10; $i++) {
$random_number = rand(1, 10);
$urls = array();
for ($n = 0; $n < $random_number; $n++) {
array_push($urls, "http://www." . (rand(1, microtime(true))) . ".com");
}
array_push($urls_to_split_up, $urls);
}
/**
* Based on http://bastian.rieck.ru/uni/bin_packing/bin_packing.pdf
* Algorithm #10: Best-fit with lookup table
*
* If you sort then your runtime will be at least O(n^2). This has a better
* runtime of O(nK) -- ie: it's a faster algorithm than using sorting.
*/
//
// Set your target size here. Anything bigger than this will not be processed.
$MINIMUM_BATCH_SIZE = 5;
// 1. Initialize a lookup table and storage
$bin_lookup = array_fill(0, count($urls_to_split_up), $MINIMUM_BATCH_SIZE);
$bin_store = array_fill(0, count($urls_to_split_up), array());
// 2. For all object do ....
foreach ($urls_to_split_up as $urls) {
// 3. Let W be the current object size
$size_of_array = count($urls);
// 4. Search suitible bin with remaining capacity
if ($size_of_array <= $MINIMUM_BATCH_SIZE) {
for ($i = 0; $i < count($bin_lookup); $i++) {
if ($size_of_array <= $bin_lookup[$i]) { break; }
}
// Actually store the URLs and subtract remaining capacity
$bin_lookup[$i] = $bin_lookup[$i] - $size_of_array;
array_push($bin_store[$i], $urls);
}
/**
* Uncomment these lines if you want to also process URL arrays bigger
* than your target size
*/
/*
else {
for ($i = 0; $i < count($bin_lookup); $i++) {
if ($bin_lookup[$i] == $MINIMUM_BATCH_SIZE) { break; }
}
$bin_lookup[$i] = $bin_lookup[$i] - $size_of_array;
array_push($bin_store[$i], $urls);
}
*/
}
// Remove unused bins
$bin_store = array_values(array_filter($bin_store));
// Display results.
print_r($bin_store);
Example Results
Array
(
[0] => Array
(
[0] => Array
(
[0] => http://www.696358599.com
[1] => http://www.1101237996.com
[2] => http://www.39990498.com
[3] => http://www.808152997.com
)
[1] => Array
(
[0] => http://www.104638105.com
)
)
[1] => Array
(
[0] => Array
(
[0] => http://www.659977343.com
[1] => http://www.528424096.com
)
[1] => Array
(
[0] => http://www.1018981549.com
[1] => http://www.343493509.com
[2] => http://www.1037396543.com
)
)
[2] => Array
(
[0] => Array
(
[0] => http://www.306146048.com
[1] => http://www.1275939888.com
[2] => http://www.1141004911.com
[3] => http://www.1389901513.com
[4] => http://www.46297440.com
)
)
[3] => Array
(
[0] => Array
(
[0] => http://www.904192341.com
[1] => http://www.275948608.com
[2] => http://www.1146600584.com
[3] => http://www.610914222.com
)
)
[4] => Array
(
[0] => Array
(
[0] => http://www.560237467.com
[1] => http://www.878781689.com
[2] => http://www.975916448.com
)
)
)
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This is pretty much the bin packing problem.
let me see...