Combine arrays, but in a specific way - php

Question

I have not even started the codeing process, because i cant figure out the logic.
I have 2 arrays
$urls = array(0 => url1,
1 => url2,
2 => url3,
3 => url4);
$domains = array(0 => domain_a,
1 => domain_b,
2 => domain_c,
3 => domain_d);
i need and output like
[0] => array ( [domain] => domain_a
[urls] => array (
[0] => url2,
[1] => url4 ))
[1] => array ( [domain] => domain_b
[urls] => array (
[0] => url1,
[1] => url3 ))
[2] => array ( [domain] => domain_c
[urls] => array (
[0] => url1,
[1] => url4 ))
[3] => array ( [domain] => domain_d
[urls] => array (
[0] => url2,
[1] => url3 ))
Until all domains has bin packed with 2 urls. The packing of the urls must be random, but the use of each url must be the same, or close to the same.

Answer 1

If you ever can't do something, the best thing is to break it down into chunks.
The answer to your question is likely to create a copy of the array of urls, and loop through the domains adding two of these urls each time — at random. When you do so, remove the item from the array. If the copy of urls is empty, create a fresh copy.
// The output
$output = [];
// The selection of arrays. We can populate this later...
$selection = [];
// Loop through every domain...
foreach($domains as $domain){
// Create the template that you want in the output. So far this is nearly the whole way there, we just need to add the random urls
$newItem = [
"domain" => $domain,
"urls" => []
];
// You want 2 urls per domain, so we'll do a for loop twice. ($i < 2)
for($i = 0; $i < 2; $i++){
// If the $selection list is empty (it will be at the start of the function, and also in your example on domain_c make a simple copy of the urls)
if(count($selection) <= 0){
$selection = $urls;
}
// Now find a random key for an item in the array
$randomKey = array_rand($selection);
// Push the item into the array of urls
$newItem["urls"][] = $selection[$randomKey];
// remove it from the array of items to pick from (so it won't come up again until you create a new copy, after all the others are used)
unset($selection[$randomKey]);
}
// Add this to the output:
$output[] = $newItem;
}

Answer 2

Using shuffle() and a simple foreach should be enough to do the job. For an arbitrary number of domains to be distributed randomly onto another number of urls use the following script:
$url=array('url1','url2','url3','url4');
$dom=array('dom_a','dom_b','dom_c');
$urls=$url; // copy the array
shuffle($urls); // shuffle the domains
$ul=count($urls); // length of $url
$dl=count($dom); // length of $dom
foreach ($urls as $k => $u)
$res[$k]=["domain"=>$dom[$k%$dl], "urls"=>[$u,$urls[($k+1)%$ul]]];
print_r($res);
See DEMO here: https://rextester.com/PFS53297

Answer 3

This code provides for a different number of domains and URLs in the input:
$urls = array(
0 => 'url1',
1 => 'url2',
2 => 'url3',
3 => 'url4'
);
$domains = array(
0 => 'domain_a',
1 => 'domain_b',
2 => 'domain_c',
3 => 'domain_d'
);
$result = [];
foreach ($domains as $domain) {
$urlsBucket = [];
while (count($urlsBucket) < 2) { // We need only 2 URLs
$randomUrl = $urls[array_rand($urls)]; // Get random URL
if (in_array($randomUrl, $urlsBucket)) { // To avoid duplication in the URL list
continue;
}
$urlsBucket[] = $randomUrl;
}
$result[] = [
'domain' => $domain,
'urls' => $urlsBucket
];
}
var_dump($result);
Output:
array(4) {
[0]=>
array(2) {
["domain"]=>
string(8) "domain_a"
["urls"]=>
array(2) {
[0]=>
string(4) "url2"
[1]=>
string(4) "url1"
}
}
[1]=>
array(2) {
["domain"]=>
string(8) "domain_b"
["urls"]=>
array(2) {
[0]=>
string(4) "url2"
[1]=>
string(4) "url4"
}
}
[2]=>
array(2) {
["domain"]=>
string(8) "domain_c"
["urls"]=>
array(2) {
[0]=>
string(4) "url3"
[1]=>
string(4) "url1"
}
}
[3]=>
array(2) {
["domain"]=>
string(8) "domain_d"
["urls"]=>
array(2) {
[0]=>
string(4) "url1"
[1]=>
string(4) "url2"
}
}
}
DEMO: https://paiza.io/projects/c9rXHcprCgsWnUlJ9UNNsg?language=php