PHP: How to find connections between users so I can create a closed friend circle?
- by CuSS
Hi all,
First of all, I'm not trying to create a social network, facebook is big enough! (comic)
I've chosen this question as example because it fits exactly on what I'm trying to do.
Imagine that I have in MySQL a users table and a user_connections table with 'friend requests'. If so, it would be something like this:
Users Table:
userid username
1 John
2 Amalia
3 Stewie
4 Stuart
5 Ron
6 Harry
7 Joseph
8 Tiago
9 Anselmo
10 Maria
User Connections Table:
userid_request userid_accepted
2 3
7 2
3 4
7 8
5 6
4 5
8 9
4 7
9 10
6 1
10 7
1 2
Now I want to find circles between friends and create a structure array and put that circle on the database (none of the arrays can include the same friends that another has already).
Return Example:
// First Circle of Friends
Circleid => 1
CircleStructure => Array(
1 => 2,
2 => 3,
3 => 4,
4 => 5,
5 => 6,
6 => 1,
)
// Second Circle of Friends
Circleid => 2
CircleStructure => Array(
7 => 8,
8 => 9,
9 => 10,
10 => 7,
)
I'm trying to think of an algorithm to do that, but I think it will take a lot of processing time because it would randomly search the database until it 'closes' a circle.
PS: The minimum structure length of a circle is 3 connections and the limit is 100 (so the daemon doesn't search the entire database)
EDIT:
I've think on something like this:
function browse_user($userget='random',$users_history=array()){
$user = user::get($userget);
$users_history[] = $user['userid'];
$connections = user::connection::getByUser($user['userid']);
foreach($connections as $connection){
$userid = ($connection['userid_request']!=$user['userid']) ? $connection['userid_request'] : $connection['userid_accepted'];
// Start the circle array
if(in_array($userid,$users_history)) return array($user['userid'] => $userid);
$res = browse_user($userid, $users_history);
if($res!==false){
// Continue the circle array
return $res + array($user['userid'] => $userid);
}
}
return false;
}
while(true){
$res = browse_user();
// Yuppy, friend circle found!
if($res!==false){
user::circle::create($res);
}
// Start from scratch again!
}
The problem with this function is that it could search the entire database without finding the biggest circle, or the best match.
