Langton’s Ant in p5.js

Simon wrote this JavaScript code for Langton’s Ant (a type of Cellular Automaton) himself, inspired by Daniel Shiffman’s description/version in Processing (Java) during the Coding Train live stream on January 5.

Link to Simon’s sketch:

Simon later also made a pixel level version:

And a version with multiple ants:

(Simon also loves the Numberphile video about how Langton’s Ant works and forms a mysterious “highway” after a certain number of moves).


The Genetic Algorithm Game Bug Solved!

Simon’s version of the Citius Invaders game in Processing is finally working! The big bug that seemed so unsolvable (enemies endlessly crossing over) has been defeated!

Siraj Raval presented this game in Python during Week 9 of his “Math of Intelligence” course. Simon’s is a simplified version that still incorporates a genetic algorithm.

Link to code on github at:

Link to our previous post on this project:

Link to Simon’s archived Live Stream about the project:

Problem with a Genetic Algorithm Game

Simon has been working very hard at making his version of the Citius Invaders game that Siraj Raval presented in Python during Week 9 of his “Math of Intelligence” course. It’s a simplified version that still incorporates a genetic algorithm. Simon’s plan is to code the same game in P5 during his next live tutorial (at 17:00 CET on 30 November). Unfortunately, after many lines of code in several files, when the game was nearly ready, he faced a problem he doesn’t know how to resolve. He tried getting some online help via the Coding Train Slack channel but didn’t get much feedback. The code is now on github at:

Here is how Simon describes the problem:

Hi! I’m working on a “Citius Invaders” game, and I have a problem.
In the game, there are enemies, a spaceship, and bullets that it shoots.
The parameters of the game are:
* The game starts with 6 enemies.
* The minimal amount of enemies is 4.
* The maximal amount of enemies is 100.
The rules of the game are:
* When a bullet collides with an enemy, the bullet and the enemy get deleted.
* If there are 4 enemies on the screen, you’re not allowed to shoot any bullets any more.
* If there are 100 enemies on the screen, you’ve lost the game.
* The enemies reproduce every 5 seconds (this amount of time decreases every generation).
The goal of the game is to stay as close to 4 enemies as possible.
The problem is that: After the 5 seconds, the enemies don’t stop crossing over! I think the order that I’m crossing them over is wrong. They breed (cross over) forever and that makes the game pause forever. Maybe the algorithm in which I let them cross over is wrong. I have a `while` loop somewhere, maybe it became a forever loop. The `while` loop is at line 52 in `Population.pde`:

 while (!selectedEnemies1.isEmpty() || !selectedEnemies2.isEmpty()) {
 int index1 = int(random(selectedEnemies1.size()));
 int index2 = int(random(selectedEnemies2.size()));
 if (index1 == index2) {
 index2 = (index2 + 1) % selectedEnemies2.size();

Below are a some videos showing Simon at different stages of the project. In the top video, he speaks of the difficulties he encountered with the frame rate and the genetic algorithm.



At Het Pass in Mons (Bergen)

Simon is not really into museums. He prefers to learn things at his own pace and dislikes crowds. The pictures below are from our visit to Het Pass, a science museum in Wallonia, near the French border. The museum is situated in what formerly were mining facilities, the exhibits are interactive, spread out in several oddly shaped buildings connected by industrial bridges and escalators. I believe Simon actually enjoyed the electricity and the genetics rooms, even though the two of us got struck by the electricity from the plasma ball  (painful!):






Evolutionary Steering Behaviors Game

Note: See the update at the bottom of this post!

We’ve had quite a dramatic situation here for the past couple of days, after Simon turned Daniel Shiffman’s Evolutionary Steering Behaviors Coding Challenge into a game in Processing (Java) and then also in JavaScript (with p5). After completing the game in JavaScript, Simon wanted to add a new feature – a checkbox he programmed using the p5.js library. The checkbox would give the player the option to play with or without the timer, adjust the timer and also had a “New game” button. In the end it turned out that the checkbox didn’t really work. Simon was very upset and it took me hours to talk him into putting the game online even though the checkbox didn’t function (he wanted everything to be perfect) and ask for advice. “I have got a problem with a p5 element: In my setup function, I defined my checkbox. In my reset function, my checkbox is undefined. Why?” – Simon asked in the “Share Work” section of the Coding Train Slack channel, where he has the opportunity to communicate with experienced programmers. He received quite a lot of help and was enthusiastic about it at first, but for some reason, he hasn’t tried the solutions he was suggested. Perhaps it’s his gut feeling that the bind function suggested is still too difficult at the moment. I have decided not to push anymore and trust him on this one, although it’s always a dilemma for me whether I should sometimes “force” him into taking instructions from others or let him solely rely on his fantastic intrinsic autodidact mechanisms. The second seems to work better in terms of the learning process, but I do push him into sharing his work.

Evolutionary Steering Behaviors game. Asking help in Slack 10 Jul 2017 3Evolutionary Steering Behaviors game. Asking help in Slack 10 Jul 2017 4Evolutionary Steering Behaviors game. Asking help in Slack 10 Jul 2017 5Evolutionary Steering Behaviors game. Asking help in Slack 10 Jul 2017 6Evolutionary Steering Behaviors game. Asking help in Slack 10 Jul 2017 7Evolutionary Steering Behaviors game. Asking help in Slack 10 Jul 2017 8

Evolutionary Steering Behaviors game. Asking help in Slack 10 Jul 2017 2

Simon’s game is online at:

In the videos below Simon shows how he made the game. It’s an ecosystem type of genetic algorithm (with no generations), where the organisms (autonomous steering agents) clone themselves. The autonomous steering agents evolve the behavior of eating food (green dots) and avoiding poison (red dots). Simon added two invaders into the game, one giving food and the other randomly spreading poison. The player can control the “good” invader by moving him and making new food. The goal of the game is to make the agents survive for as long as possible.

The Processing (Java) version:

The thinking behind the game (Simon explains everything at the whiteboard):

The JavaScript version (now online):

In the last video, Simon talks about his problem with the p5 element.


Evolutionary Steering Behaviors game seek algorithm part 1. DESIRED equals TARGET minus POSITION:

Evolutionary Steering Behaviors game seek algorithm part 1. DESIRED equals TARGET minus POSITION 4 Jul 2017

Evolutionary Steering Behaviors game seek algorithm part 2. STEERING equals DESIRED minus VELOCITY:

Evolutionary Steering Behaviors game seek algorithm part 2. STEERING equals DESIRED minus VELOCITY 10 Jul 2017

UPDATE: When Simon saw Daniel Shiffman’s comment on Slack this morning (Daniel saying Simon did a fantastic job and that he might even include Simon’s game in the next Live Stream), he sat down and applied the bind function as suggested by his older peers above – without any incentive on my behalf! And it worked! I think we’ve hit a true milestone again. Simon has this growing feeling that he’s got friends out there, his tribe, who understand and who are ready to help.

One day later: Simon had another chat with his friends on Slack and got a lot of help with the last remaining small bug in his game (the New Game button didn’t start a new game if the player had chosen to play with no timer but jumped to Game Over instead). In the video below, Simon shows how that problem got solved:

Error with Genetic Algorithm. What is wrong?

Simon was almost done translating Smart Rockets example no. 2 (Smart Rockets Superbasic) from Daniel Shiffman’s The Nature of Code, from Processing (Java) into JavaScript in Cloud9, when he got an error using genetic algorithm: the dna seems to be undefined while Simon did define mom and dad dna.

This is Simon’s translation online in Cloud9:

This is when he first discovered the bug and tried different solutions:

And this is the same project before he introduced the genetic algorithm:

In the next video Simon boasts he found two errors in his code and hopes that the problem would be solved, but alas, the rockets still vanish from the canvas after a few seconds:

Simon is officially stuck here.

On the positive side, this project did get us to read more about the actual human DNA and the way it works.


Cellular Automata in Arduino

Yesterday Simon spent the whole day studying the concept of Cellular Automaton (CA), a discrete model of a system of “cell” objects used in physics, math and theoretical biology. He learned a lot from Daniel Shiffman’s tutorials on Cellular Automata and his book The Nature of Code (Chapter 7).

Simon describes Cellular Automaton as a set of rules for getting nature-like patterns. 1D cellular automata are static (think of a pattern resembling the Pascal triangle) and 2D are not static (the most famous example is Conway’s Game of Life).

The mathematician who made cellular automata a big thing (and even Turing-compatible!) was Stephen Wolfram. Simon also looked at some of Wolfram’s writings. Wolfram’s book A New Kind of Science is intimidating (in content and size) but full of graphic illustrations and available for free at

A CA is basically a grid where cells live, each cell in a particular state (the simplest example being “1” or “0”). In Processing, it’s possible to have a CA draw a beautiful pattern this way. Simon tried to write a CA program in another language. He tried writing it in Python on his RaspberryPi first, but I overheard him say “don’t know how classes really work in Python, let’s try Ruby – I know how classes work in Ruby!” Then I saw him move over to the desktop and plug his long forgotten Arduino in. He said he now wanted to translate a CA code into C. Of course, there would be no pattern, but he wanted to have the Arduino “spit out numbers in the console” instead. Eventually he got an error and gave up, but it was intriguing to observe him.

The videos below show Simon talk about CA and program a CA in Arduino (C):










Cellular Automation 31 Mei 2017

Smart Rockets Coding Challenge translated into Processing (Java)

And here is Simon’s translation of Daniel Shiffman’s Smart Rockets Coding Challenge into Processing (Java). This challenge (originally in JavaScript) was about implementing a genetic algorithm from scratch and create “smart rockets” (based on a simulation by Jer Thorp). The rockets evolve the “best” path to a target, moving around obstacles.

Looping through an array lecture

In these videos Simon explains looping through an array and adding while simultaneously removing things from that array. He recorded this presentation while working on an evolution simulation (Evolutionary Steering Behaviors, see previous post).