Trouble Building Football Schedule

[petemcw]

Hey Everyone!

I am messing around with a fantasy football project. Trying to automate the process a little bit.

I need to come up with a function/class that when passed three parameters, (number of divisions in a league / number of teams in the divisions / number of weeks in season), it will spit out a schedule for the different teams to play each other.

Some sample data might be:

Weeks: 15
Divisions: 2
Teams: 4

I have something that kind of works, but I end up having a team playing another team like 9 times out of 15 instead of playing the other teams equally. The whole thing is basically unreliable.

I wonder if there isn't some mathimatical equations that would calculate the different combinations? --> I'm no good at math!

Any help is greatly appreciated!!!

[Natty_Dreadlock]

hi, pls post the code u already got so that someone can help u...

[petemcw]

Well, the code is out of control. Basically we try to loop through all these different possibilities and it doesn't really work.

Ideally, I'm wondering if there is some math that will calculate the possibilities.

Here is the basic generation function. There is too much misc. code in the class to post it all. But maybe this will give you all an idea.

	function generate_schedule()
	{
		// loop through weeks
		foreach($this->divisions as $key => $division)
		{
			set_time_limit(60 * 20); // 20 minutes

		$this->d->w('LOOPING DIVISIONS, count: ' . $key);

		// division has an array of teams, loop 
		//through division_play_self_num, stay under num weeks limit
		for($i = 1; $i <= $this->division_play_self_num; $i++)
		{
			$this->d->w('division playing self: ' . $i);
			// have a division play itself
			$this->play_own_division(&$this->divisions[$key]) ;
		}
	} // end loop

	// loop again
	if($this->play_other_teams)
	{
		foreach($this->divisions as $key => $division)
		{
			set_time_limit(60 * 20); // 20 minutes
			// now play other teams, fill remaining weeks
			$this->d->w('division playing other teams...');
			// now, just play other teams
			$this->play_other_teams(&$division);

		} // end loop
	} // end if


	// now, rendomize the weeks and the games
	shuffle($this->schedule); // randomize weeks
	$this->schedule = $this->shuffle_elements($this->schedule); // randomize game order
	$this->shuffle_schedule_games(); // randomize team order in games

	return true;
}

Thanks again!

[MarkR]

You should try to make a list of rules you want to implement, or more precisely, a set of predicates you want to be true, for example:

• In a season, each team must play each other team twice, once at home and once away
• Each team must alternately play home and away (I have no idea if this typically applies to real leagues, it's a guess)

Then you can write a function which tests these predicates and immediately know whether your algorithm is correct.

Personally, I'd build it up on a slot-by-slot basis (A slot being a particular day that games take place), by just figuring out:

• For each given team X, who is not already playing this slot, find the set of teams who have not already played them at the venue they are supposed to be playing this slot (home/away). Assign them a game arbitarily from this set.
• Continue until all teams are playing in this slot
• Move on to next slot, until the season is finished

I've no idea in my head whether every possible scenario is soluble or whether it's possible to get "stuck" later in the season if you make mistakes allocating earlier fixtures. Nor do I have any idea whether it makes a difference whether there is an odd or even number of teams etc.

Mark

[Natty_Dreadlock]

hi,
i think i solved your problem. check out the attached zip containing football.php, which also contains example code on how to use my function generateSchedule. pls note the funtion calculates a schedule for one half of a season, so in order to get the second half, u gotta loop through the array and swap the team names.
btw, where can i see your code working? is it a commercial or private project??
hth

[petemcw]

Natty - Wow!

Thanks for the example script. I think it will help us get to where we need to be! The project is running on my local network, so it isn't live on the Internet yet.

The few things we may have to tweak to get this running exactly the way I need are:

1) Every team MUST play every week
2) Each team can only play ONCE per week
3) A team can not repeat play another team until all teams have played each other

Those are basically some rules we need to follow. Along with that, the number of matches (games) per week is always half the number of teams. The number of weeks it will take for all the teams to play each other is (NUM_OF_TEAMS - 1). So if we have 10 teams, it will take 9 weeks of 5 games per week for every team to play each other once.

I guess does still does sound like some pretty complicated stuff. Thanks again for your help. If all that makes sense to you, I'd sure be open to more suggestions.

[Natty_Dreadlock]

hi,
ok

@2 Each team can only play ONCE per week - on my machine, the script does not create schedules with a team playin more than once a week, does it?
@3 A team can not repeat play another team until all teams have played each other- i think that's the way the script calculates the schedule, isn't it.

Those are basically some rules we need to follow. Along with that, the number of matches (games) per week is always half the number of teams. The number of weeks it will take for all the teams to play each other is (NUM_OF_TEAMS - 1). So if we have 10 teams, it will take 9 weeks of 5 games per week for every team to play each other once.

just pass these parameters to the funtion and it should work...
@1: Every team MUST play every week - seems to be a little more complicated, but might work if u pass the right parameters i'll check it out.
hth