PHP Random Team Schedule Generator - Round Robin Scheduler

After getting negative feedback from asking this question in a new question... here is my revised question. Yes it is the same project I am working on, but I was unclear that I needed to basically have a Round Robin type of scheduler.

I'm working on a Round Robin Style Hockey League Scheduler, and need some help.

The overall goal is for the end admin user to be able to punch in 3 variables and have it perform a round Robin style schedule until the WEEKS counter has been hit. Below is an example of the amount of teams and the amount of weeks games are played.

$Teams = array('team1','team2','team3','team4','team5','team6','team7','team8');
$Weeks = 16;

The goal is to have it loop 16 times, making 4 games a week, having each team playing 1 time a week. The round robin algorithm should have teams playing different teams each week until all possibles combinations have been made, but not exceeding 16 weeks. In the event that we only have 4 teams or less teams than possible combinations, we would need to have the round robin start over again until the weeks number was hit.

EDIT:

I am about 90% into what I needed this script to do... but I am stuck on one thing. I need help with merging a multi-dimensional array.

First are the Tiers. Next are the Weeks (all are week 1). Then are the Games for the team match up.

Array
(
[1] => Array
    (
        [1] => Array
            (
                [1] => Array
                    (
                        [home] => Whalers
                        [visitor] => Lumberjacks
                    )

                [2] => Array
                    (
                        [home] => Team America
                        [visitor] => Wolfpack
                    )

            )

    )

[2] => Array
    (
        [1] => Array
            (
                [1] => Array
                    (
                        [home] => Warriors
                        [visitor] => Litchfield Builders
                    )

                [2] => Array
                    (
                        [home] => Icemen
                        [visitor] => Nighthawks
                    )

            )

    )

[3] => Array
    (
        [1] => Array
            (
                [1] => Array
                    (
                        [home] => The Freeze
                        [visitor] => Devils Rejects
                    )

                [2] => Array
           开发者_C百科         (
                        [home] => Cobras
                        [visitor] => New Haven Raiders
                    )

                [3] => Array
                    (
                        [home] => Crusaders
                        [visitor] => Whalers
                    )

                [4] => Array
                    (
                        [home] => Blizzard
                        [visitor] => CT Redlines
                    )

            )

    )

)

I want the end result to drop the tier and merge all same weeks games together to look like the following:

Array
    (
        [1] => Array
            (
                [1] => Array
                    (
                        [home] => Whalers
                        [visitor] => Lumberjacks
                    )

                [2] => Array
                    (
                        [home] => Team America
                        [visitor] => Wolfpack
                    )

                [3] => Array
                    (
                        [home] => Warriors
                        [visitor] => Litchfield Builders
                    )

                [4] => Array
                    (
                        [home] => Icemen
                        [visitor] => Nighthawks
                    )

                [5] => Array
                    (
                        [home] => The Freeze
                        [visitor] => Devils Rejects
                    )

                [6] => Array
                    (
                        [home] => Cobras
                        [visitor] => New Haven Raiders
                    )

                [6] => Array
                    (
                        [home] => Crusaders
                        [visitor] => Whalers
                    )

                [8] => Array
                    (
                        [home] => Blizzard
                        [visitor] => CT Redlines
                    )

            )

    )

Maybe something like this?

<?php
$teams = array(
    'Team 1',
    'Team 2',
    'Team 3',
    'Team 4',
    'Team 5',
    'Team 6',
    'Team 7',
    'Team 8'
);

function getMatches($teams) {
    shuffle($teams);
    return call_user_func_array('array_combine', array_chunk($teams, sizeof($teams) / 2));
}

for ($i = 0; $i < 14; $i += 1) {
    print_r(getMatches($teams));
}

I didn't really get how you define the schedule, so if you can explain this a bit, I'll try to help.

Pop one off, randomize, pop another. There's your game. If one is left over, some random team has to be a workhorse and play two games this week:

for ($week=1; $i<=$totalWeeksPlayed; $i++)
{

  $games = 0;
  $temp = $teams;

  while (count($temp) > 1)
  {
    $team = array_shift($temp);  
    shuffle($temp);
    $opponent = array_shift($temp);
    $game[$week][$games] = $team . ' vs' . $opponent;
    $games++;
  }

  if (count($temp) == 1)
  {
    $workhorses = $teams;
    unset($workhorses[array_search($temp[0], $teams));
    shuffle($workhorses);
    $team = $temp[0];
    $opponent = array_shift($workhorses);
    $game[$week][$games] = $team . ' vs' . $opponent;
    $games++;
  }

}

Question below copied from above.

Correct me if I get this wrong, but if all teams have to play on the same regular basis, is it even possible to have all teams play the same amount of matches, if there is an odd number of teams? – Yoshi May 3 '11 at 15:05

Michelle,

The number of teams you are trying to pair-up (in this case 8 teams for 16 weeks) can be a daunting task, and is just the beginning of the "scheduling process". Once the correct, balanced team pairings have been determined, it's just the beginning of putting a schedule together for distribution. Next, a list of the 4 weekly time slots includes the; day of the week, start time and location name for each time slot for the whole 16 week season. Comment: What would be most helpful for you is to get an 8 team scheduling matrix that has balanced opponent, and home & away status. It makes a big difference in the quality of a schedule. It's important to evenly distribute early and late time slots, equal home & away status, and equal team distribution with opponents. Most of the balance is accomplished by using a balanced team pair matrix.

After 35 years of teaching, coaching and scheduling sports in the Boston area, I can offer the following information. Creating league or game schedules for sports organizations seems to be a never ending task shared by many and is repeated over and over as the ages of the participants grow and those running the leagues change, the learning curve associated with creating schedules is significant for those who take over.

With that said, I am amazed at how many highly educated mathematical wizards are involved with trying to come up with the perfect solution (algorithm) that will solve one's scheduling problem. Myself and a friend (who is a mathematical/programmer genius) over a period of 3 years created software that perfectly balances all the important components when creating schedules for 4 to 22 teams. What we learned is that there is no algorithm that can handle all the possible variables that are added to the normal variables to create balanced schedules. What I am saying is there are just as many "what ifs" as there are mathematical permutations and combinations that deal with just creating a team matrix listing opponents and home & visitor status of games.

For example: Let's create a perfectly balanced schedule for an 9 team division playing 4 games a week. After nine weeks all teams have played played 8 games, all have had 1 bye, all have played two times in each of the 4 time slots, and all have been scheduled as the home team 4 times and the visitor team 4 times.

What more could anybody want? Well now comes the fun. Because the 4 time slots you chose has 2 games each Saturday, and 2 games each Sunday, the first problem pops up (after the schedules are created, published and passed out, when 2 coaches from 2 different teams call and say they work Saturdays, can you move our games to Sundays? Sure, I can do that. I'll just make the changes, re-publish and re-distribute the schedules.

After the new schedules are distributed, several days later, a different coach calls up and says, "Hey, you moved some of my games to Saturday, I work Saturdays.., move them back". The phone rings again. This time a it's a coach from another team and says they are in a tournament the 5th week of the schedule and can't play that week. Finally the last call comes in from yet another coach. He says the parents of one of his players teaches CCD classes Sunday afternoons, and half of his team is in the CCD class and wants to move all our Sunday games to Saturday. Enough!

My point is no matter what you do or how perfect a schedule is, the best solution is to find out as many of the player/coach team limitations or restrictions before you assign the playing days and time slots to any schedule. These unpredictable variables makes a mess out of a perfect schedule. People do get angry and complain when undesirable schedules are distributed. When a schedule is bad enough, some parents won't sign their youngster to play the following year. This happens when you have a young family with two or three small children, and Dad's work limits his ability to be there. When there is an early morning game, I think you can see the difficulty for Mom's when it all falls on her shoulders.

For those that are new to scheduling, stay with it. It gets better over time after you gain a little experience dealing with the problems. If you purchase a scheduling software program to calculate team pairs, be careful. Insist on seeing a full single round robin of the schedule they create. Check for the things described above (about balance and distribution).

Bob R

Given a table of teams, say team ( teamname );

And a table of fixtures

fixture ( date; );

With the relationship decomposed by 'playing'

playing ( fixture_date. teamname );

Then it's would simply be a matter of iterating through each date, then team and selecting a team at random who does not already have a fixture for that date, and who have not played the selected team (or not played the selected team recently).

Although a simpler solution would be to have team[n] (where n is 0....number of teams -1) play team[(n+(number of teams)) % X] for varying values of X.