Football Simulation Engine v3

2 Years ago I published my first node package module (npm) in npmjs to allow football match results to be simulated. Yesterday I uploaded the latest version FootballSimulationEngine-v3.0.1 which can be installed by running:
          npm install footballsimulationengine

What's New?

startPOS and relativePOS have changed

The biggest - and breaking - change was to update the arrays used to track where players currently are on the pitch (startPOS) and where players are moving towards (relativePOS). These were not very descriptive and resulted in several GitHub issues so they have been changed to better reflect what they do. "startPOS" is now "currentPOS", "relativePOS" is now "intentPOS".

"currentPOS": [340,0],

"fitness": 100,

"injured": false,

"originPOS": [340,0],

"intentPOS": [340,0],

Tests tests tests

I have been reading more and more about the importance of tests and clean code, in fact its been prominent on this blog:

• https://aidensgallyvanting.blogspot.com/2019/03/observations-of-test-driven-development.html 
• https://aidensgallyvanting.blogspot.com/2019/03/enforcing-test-driven-development-into.html
• https://aidensgallyvanting.blogspot.com/2019/05/practising-clean-code-in-nodejs.html

As described, I have added lots and lots of tests into the code making it more readable, easier to make code changes, has led to variables and functions being named more accurately. The result is 143 passing (199ms) tests and roughly 55% test coverage.

55.88% Statements 1401/2507

44.32% Branches 655/1478

82.13% Functions 170/207

53.14% Lines 1227/2309

Penalty Position - Corner and Freekicks

Players no longer form an arbitary collection of bodies at a set location for freekicks and corners, instead they now gather in the penalty box which is a defined dimension on the pitch. This makes corner taking more realistic and improves goal opportunities from corners.

Identifiers

Previously, the current ball holder and the team they were playing were matched against their names for certain logic. i.e. can the player kick the ball? First, we need to know if that player has the ball. Now each match, player and team are given an identification number during initiation. 

{

"matchID": "78883930303030001",

"kickOffTeam": {

"teamID": "78883930303030002",

"name": "ThisTeam",

"rating": 88,

"players": [

{

"playerID": "78883930303030100",

 

Red Cards

Players who get red cards will no longer be part of the playing action. This is shown by current position being set to ['NP', 'NP'] which means 'Not Playing'. If the current position is set the player will not be targeted for passing and will not make any movements.

Skill Rating Utilization

Player skills are better utilised including to make shots on or off target depending on their skill against a random number generation i.e. players with shooting skill of 40 will be less likely to shoot on target than players with shooting skill of 70. This is also applied for saving shots that are in the box with the skills of the goalkeeper determining if the ball is 'saved' or not when in reach. 

Future iterations will take this further for more sophistication. If you have any thoughts for how to do this be sure to raise an issue in GitHub.

Player Stats Improvements

Player statistics from during the game have been greatly improved with statistics for fouls, passes, shots and tackles. This will improve reporting of player information. 

If there are others that can/should be added, raise an issue in GitHub.

'goals': 0,

'shots': {

'total': 0,

'on': 0,

'off': 0

},

'cards': {

'yellow': 0,

'red': 0

},

'passes': {

'total': 0,

'on': 0,

'off': 0

},

'tackles': {

'total': 0,

'on': 0,

'off': 0,

'fouls': 0

}

Conclusion

There are still some improvements to be made, to player movement (which still isn't quite there), passing statistics, intelligence of decisions being made and whole lotta tests to be added. I'll be blogging soon about how I've used this latest version to simulate the 2019/2020 season to showcase how the engine can be used to simulate a season for a football manager game.

Let me know what you think, either in the comments, or by raising an issue on Github or emailing me on aiden.g@live.co.uk! Happy footballing!

Football Simulation Engine v2.1.0, v2.1.2 and v2.2.1

The football simulation engine node module has been available for just over a year now and has a couple of hundred downloads, and an interaction of a fair few people via GitHub. Part of that interaction has led to requests for changes to be made to the modules functions to either make the game easier to control or alter. 

Whilst making the changes other issues were thrown up such as the ball not continuing to move with the players when they were in possession, and in other cases the ball remaining in the players control after it had been kicked. The new versions - specifically version 2.2.1 - resolves these issues and provides a much better and more reliable output.

Refactoring 

The first big change was the removal of the async module. Two reasons for this were that a) it didn’t need it, b) I’ve grown a distaste for dependencies in my NodeJS programs. On top of this there were changes to allow for the latest node version to be used which included using let, const instead of var which good practice dictates and the general removal of promises which were also not necessary. 

General input from https://github.com/dashersw has been instrumental which has included improving error throwing as well as removing repetition. As such the code has been regularly reduced or made easier to understand with game examples now available.

Testing 

Part of my own journey has been to begin looking at Test Driven Development (TDD). Unfortunately, I could only apply it in this module retrospectively but will be adding test cases for all new functionality before I code it in future. 

For now, I have added testing for the three main exported functions and testing of validation of input. This is because it is where users are most likely to get stuck. My new goal is also to raise tests around whatever issues come through. One example is https://github.com/GallagherAiden/footballSimulationEngine/issues/33 where tests were added to validate the “ClosestPlayer” functions.

Adding tests has improved the game, because it has caught a number of interesting ‘perks’ of the code written where tests that should have passed actually failed. Which is good, as it shows TDD in action. 

Finally, part of the testing now includes End to End testing through Match Simulation of varying team ratings which shows expected results for teams of different skills.

New Functionality

After a review of the games being played there were a few obvious changes that could be made. Allowing more tackleswas one such whereby players rarely were able to take the ball off each other before, this has now changed and with it comes an improved risk of players committing fouls. 

The greatest new functionality was to stop the ball moving instantaneously, instead the ball moves over a period of iterations. This includes an x, y and z movement which factors in the height of the ball against the height of another player. This has allowed even greater play by introducing interception of the ball as it moves. 

Another big new function to the simulation was in the calculation of offside and the beginnings of some simple player marking. Other improvements have been possible with the ball movement change which includes; direction of player movementso players attack in the right direction, and better passing to stop players constantly passing to the keeper.

Finally, the way shots were taken, calculated and checked for so that own goals are awarded to the correct teams and shots occur over time. This has also led to an improvement of the ability for keepers to save shots as the ball enters their area.

Finally, a player fitness parameter has been added however this has no impact on the game currently and is merely additional information for people using the simulation engine as a manger game. This also includes an action parameter for each player which allows the move performed by each player determined by the simulator to be overridden.

Fixes

There have been a number of little fixes such as elimination of incorrect reporting of player possession of the ball. Changes have been made so that the closest player to ball or a position now gives a more accurate output.

Players now move with the ball at their feetwhich was quite a major bug in previous versions.

The changes made have had a massive impact on game play which you can see on the video I created for the latest version.

There are other changes coming in version 3 which looks to make the iteration json read better and make it more accessible. Other possibilities will be the removal of players from game play e.g. by red or yellow cards and the ability for team rating and other skills and fitness to have a greater impact on individual player performance.

I would love to receive feedback and requests for improvement which can be added here: https://github.com/GallagherAiden/footballSimulationEngine/issues

Alternatively you can email me here.

Happy footballing and thank you for downloading and using the module. 

Football Match - Using football simulation engine

I recently created a football simulation engine for npm which I talked about here.

I also posted a youtube video of me demonstrating the code, and after some interest I thought I would upload the helper code I used in order to visualise the match!

You can access the github page here: https://github.com/GallagherAiden/footballsimulationexample



Here's the read me:
# Football Simulation Example

## Install
1. Download the project onto your system ({dir})
2. cd {dir}
3. run ``npm install``
---
## Run the Game
1. load your team into the {dir}/teams directory (you can use an existing team as an example)
2. in '{dir}/server.js' change either
```
readFile("teams/team1.json").then(function (team1) {
```
to your newly created .json file i.e.
```
readFile("teams/myTeam.json").then(function (team1) {
```
3. Set the pitch size by changing the ``pitchWidth`` and ``pitchHeight`` in '{dir}/server.js'
*Note: Any changes will need changes made to the start positions of the players*
4. run ``npm start``
5. Go To ``http://localhost:1442/match.html``
---
## Playing A Match
1. Press ``start match``
- This starts a new match where the pitch size is displayed on the screen and the players are in their correct positions.
2. Press ``play match``
- This runs '10' iterations, moving the players and give iteration logs for each iteration.
i.e. `Iteration 50: Closest Player to ball: Louise Johnson,Closest Player to ball: Aiden Smith`
3. Press ``play match`` until the iterations reach 5,000
- We can make this quicker by changing the number of iterations per "play" in {dir}/public/js/match.js
```
function getMatch() {
var iterations = 10;
for (i = 0; i < iterations; i++) {
movePlayers("/movePlayers");
}
}
```
to
```
function getMatch() {
var iterations = X;
for (i = 0; i < iterations; i++) {
movePlayers("/movePlayers");
}
}
```
where X is the number of iterations to do at a time.
4. Press ``start second half``
- This flips the players to opposite sides
5. Press ``play match`` until the iterations reach 10,000
6. Record the results

Game Example Results:

Match 1 - Team1: 5 - 3 :Team2  (same json)

Match 2 - Team1: 3 - 4 :Team2  (same json)

Match 3 - Team1: 9 - 2 :Team2  (same json)

Match 4 - Team1: 2 - 5  :Team2  (team2 higher skills)

Match 5 - Team1: 0 - 7  :Team2  (team2 higher skills)

Match 6 - Team1: 8 - 1 :Team2  (team1 higher skills)

Match 7 - Team1: 3 - 0 :Team2  (team1 higher skills)

Have fun! Let me know if you need any help: aiden.g@live.co.uk