Round-Robin Scheduling: Generating fixtures for Zone01 Kisumu's Go Foosball League

Introduction

This algorithm uses a round-robin approach, a standard method for generating fixtures in tournaments.

The Go Foosball League, presented at the #GophersKisumu Meetup on June 15th, 2024, solves the challenges faced by our community with manual management of fixtures. We were looking for a fair, efficient and automated solution that minimised human intervention. Here is how we created this fixture generating system.

The Problem
Our Go Foosball League was manually managed by a single person, leading to several issues:

• Bias in Team Formation: Players often complained about unfair team pairings.
• Scheduling Errors: Manual scheduling resulted in conflicts and errors.
• Inefficiency: The process was time-consuming and prone to human error.

To address these challenges, we needed a solution to automate the management process, ensuring fairness and reducing the potential for errors.

The Solution
The Go Foosball League has the following core features:

• Automated Team Formation: A randomization algorithm pairs strikers and defenders fairly.
• Fixture Generation: Automatically creates balanced and unbiased match schedules.
• Web Interface: A user-friendly web platform for players to view teams, fixtures, and other league details.

Technical Overview
The system is built with #Go, leveraging its efficiency and concurrency capabilities. Here's a high-level overview of the architecture:

• Backend: Handles core logic for team formation and fixture generation.
• HTTP Handlers: Manage functionalities like the home page, team list, and fixtures.
• Database Integration: Planned for future development to store player stats and match results.
• Web Frontend: Under development to provide an intuitive user interface.

Core Functionalities
Shuffling Players
The shuffle algorithm in our Go Foosball League randomizes the order of players to ensure that the team formations are fair and unbiased.

Step-by-Step Breakdown

• Seeding the Random Number Generator:
  The algorithm starts by seeding the random number generator with the current time in nanoseconds.
  This ensures that each run of the algorithm produces a different random sequence.

• Shuffling the Array:
  The rand.Shuffle function is used to randomize the elements in the array.
  The function swaps elements at random indices to achieve a shuffled order.
  The shuffle algorithm is applied to the list of defenders to randomize their order.

• Forming Teams:
  Teams are formed by pairing each striker with a randomly selected defender.
  The GenerateString function creates unique team names based on the paired players.
  

func Shuffle(arr []string) []string { 
rand.New(rand.NewSource(time.Now().UnixNano())) 
rand.Shuffle(len(arr), func(i, j int) { arr[i], arr[j] = arr[j], arr[i] }) 
return arr }

Fixture Generation
The Fixture function creates a balanced match schedule, ensuring all teams play against each other without duplication.

func Fixture(teams []types.Teams) [][]string {
    n := len(teams)
    if (n % 2 != 0) {
        teams = append(teams, types.Teams{Name: "", Striker: "", Defender: ""})
        n += 1
    }

    fixtures := [][]string{}
    for round := 1; round < n-1; round++ {
        match_list := []string{}
        for match := 0; match < n/2; match++ {
            home := (round + match) % (n - 1)
            away := (n - 1 - match + round) % (n - 1)
            if match == 0 {
                away = n - 1
            }
            if !(teams[away].Name == "" || teams[home].Name == "") {
                match_list = append(match_list, teams[home].Name + " vs " + teams[away].Name + " \n")
            }
        }
        fixtures = append(fixtures, match_list)
    }

    return fixtures
}

The Algorithm
The fixture generation algorithm in our Go Foosball League is designed to handle an even number of teams. If there’s an odd number of teams, the algorithm first adds a dummy team (a team with no players) to make the count even. The algorithm ensures every round has the same number of matches.

Step-by-Step Breakdown
Here’s a detailed breakdown of how the algorithm works:

• Input Handling:
  The algorithm accepts a list of teams.
  If the number of teams is odd, it appends a dummy team to make the total even.

• Round-Robin Scheduling:
  The algorithm uses a round-robin approach, a standard method for generating fixtures in tournaments.
  It ensures each team plays against every other team exactly once.

• Fixture Creation:
  For each round, it determines the matchups by rotating the positions of teams.
  It pairs teams in a way that minimizes repetition and ensures fairness.

• Rotation Logic:
  In each round, the first team stays fixed, and the other teams rotate positions.
  This rotation ensures that every team eventually plays against all other teams.

• Avoiding Duplicate Matches:
  The algorithm carefully tracks which teams have already played against each other.
  It generates a new list of matches for each round without duplication.

Future Work
Future plans include:

• Database Integration: For persistent storage of player stats and match results.

• Enhanced Web Interface: Improve user experience and add more features.

• Expand Functionality: Include table updating and detailed player statistics.

Check out the full code on my Github

By Bravian Nyatoro