/**
* Show the form for editing the specified resource.
*
* @param int $id
* @return Response
*/
public function search()
{
//video recommendation
//maybe is better to have a middleware applied only to search
$user = Auth::user()->mecanex_user;
if (empty($user)) {
return Redirect::route('profile.create')->with('message', 'You have to create your profile first');
} else {
$user_id = $user->id;
//only for online experiments
//calculation of DCG
$dcg = DB::select(DB::raw('select mecanex_user_id ,SUM((POWER(2,explicit_rf)-1)/log2(rank+1)) as dcg_score from dcgs where mecanex_user_id=?'), [$user_id]);
if (count($dcg[0]->dcg_score) > 0) {
DB::table('users_dcg')->insert(['mecanex_user_id' => $user_id, 'dcg' => $dcg[0]->dcg_score]);
}
DB::table('dcgs')->where('mecanex_user_id', $user_id)->delete();
//parameter for the experiment
$neighs = '3';
$list_neighs = [];
//content_based recommendation -- using the view
$results_content = DB::select(DB::raw('select video_id, title, similarity, euscreen_id FROM user_item_similarity where user=? GROUP BY video_id, title ORDER BY similarity DESC LIMIT 10'), [$user_id]);
//collaborative recommendation
// //multiplies vector of user i with every one of its neighbors and sorts them in descending order
$results_neighs = DB::select(DB::raw('select neighbor FROM user_neighbor_similarity where user=(?) ORDER BY similarity DESC LIMIT ?'), [$user_id, $neighs]);
foreach ($results_neighs as $neigh) {
array_push($list_neighs, $neigh->neighbor);
}
if (count($list_neighs) < 3) {
//content recommendation if no neighbors
$results_recommendation = $results_content;
} else {
$string_neighs = implode(',', $list_neighs);
$results_recommendation = DB::select(DB::raw(' SELECT a.user,a.video_id,user_item_similarity.title,user_item_similarity.euscreen_id, (0.5*user_item_similarity.similarity+0.5*a.score) as total_score
from (SELECT user_neighbor_similarity.user,user_item_similarity.video_id,
SUM(user_neighbor_similarity.similarity+user_item_similarity.similarity) as score
FROM user_neighbor_similarity INNER JOIN user_item_similarity on user_neighbor_similarity.neighbor=user_item_similarity.user and user_item_similarity.user IN(' . $string_neighs . ')
GROUP BY user_neighbor_similarity.user,user_item_similarity.video_id) as a INNER JOIN user_item_similarity on a.video_id = user_item_similarity.video_id and a.user=user_item_similarity.user where a.user=(?) ORDER BY total_score DESC LIMIT 10'), [$user_id]);
}
}
//used for online experiments - creation of dcg table
$index = 0;
foreach ($results_recommendation as $result) {
$index++;
$video_id = $result->euscreen_id;
// $video_id=$result->video_id;
$dcg = Dcg::firstOrNew(['mecanex_user_id' => $user_id, 'video_id' => $video_id]);
$dcg->rank = $index;
$dcg->save();
}
return view('video.recommendation', compact('results_recommendation'));
}
