Public
Edited
Dec 25, 2023
parameters = ({
gamma: .9,
movingProbabilities: {front: 0.8, left: 0.1, right: 0.1, back: 0.0},
worldSize: new Vector(4, 3),
wallFunc: (x, y) => (x === 1 && y === 1),
rewardFunc: (x, y) => {
if (x === 3 && y === 1) return +1;
if (x === 3 && y === 2) return -1;
return 0;
},
listOfActions: [A.left, A.up, A.right, A.down],
agent: {
startPosition: Vector.ZERO,
}
})
graphics = ({
color: themeOptions.themeColors[themeOptions.currentTheme],
prop: {
rectSize: 25,
canvasSize: new Vector(500, 300),
}
})
THEMES = ({ light: "lightTheme", dark: "darkTheme" })
canvas = {
const canvas = document.createElement('canvas');
const size = graphics.prop.canvasSize;
canvas.width = size.x;
canvas.height = size.y;
const c = canvas.getContext('2d');
const worldSize = new Vector(4, 3);
const rectSize = Math.min(size.x / worldSize.x, size.y / worldSize.y);
c.clearRect(0, 0, size.x, size.y);
c.fillStyle = graphics.color.background;
for (let i = 0; i < 4; i++) {
for (let j = 0; j < 3; j++) {
c.fillRect(rectSize * i, rectSize * j, rectSize - 1, rectSize - 1);
}
}
return canvas;
}
class Gridworld {
constructor(size = parameters.worldSize) {
this.size = size;
this.wallFunc = parameters.wallFunc;
this.rewardFunc = parameters.rewardFunc;
this.listOfActions = parameters.listOfActions;
this.movingProbabilities = parameters.movingProbabilities;
// size.y = number of rows, size.x = number of columns
this.agent = {};
this.agent.pos = parameters.agent.startPosition.copy();
// Q matrix is (set of states) * (set of actions), |Q| = |states| * |actions| = (width * height) * 4
this.agent.Q = new Array(this.size.y).fill() // create rows
.map(_ => new Array(this.size.x).fill() // create colums
.map(_ => new Array(this.listOfActions.length).fill(0))); // create actions
}
isWall(pos) {
return !pos.inBounds(Vector.ZERO, this.size) || this.wallFunc(pos.x, pos.y);
}
getReward(pos) {
return this.rewardFunc(pos.x, pos.y);
}
modifyDirection(dir) {
const r = Math.random();
const relativeDirNames = ["front","right","back","left"];
const probs = relativeDirNames.map(dirName => this.movingProbabilities[dirName]);
const i = choice(probs, r);
return rotateBy90(i, dir);
}
makeAction(action) { // in case of gridworld: action ~ direction vector
const lastAgentPosition = this.agent.pos;
// modify action using moving probabilities
const modifiedAction = this.modifyDirection(action);
const nextCell = this.agent.pos.add(modifiedAction);
if (!this.isWall(nextCell)) {
this.agent.pos = nextCell;
}
const reward = this.getReward(lastAgentPosition);
return {state: this.agent.pos, reward};
}
}
{
let world = new Gridworld({x: 4, y: 3});
world.agent.pos = new Vector(3, 2);
return world.agent.Q;
}
test.all()
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