let gridMajor = 100;

let r = 4;

let points = [];

let halfW, halfH;

​

​

function setup()

{

  createCanvas(400, 400);

  halfW = floor(width / 2);

  halfH = floor(height / 2);

}

​

function draw()

{

  background(40);

  DrawGrid();

  DrawAllPoints();

  DrawArithmeticMean();

  DrawGeometricMean();

}

​

​

function mousePressed()

{

  if (mouseButton !== LEFT) return;

  if (keyIsDown(SHIFT)) // delete a point

  {

  }

  else

  {

    AddPoint(mouseX - halfW, halfH - mouseY);

  }

}

​

​

function AddPoint(x, y)

{

  print(`Adding point (${x}, ${y})`);

  points.push({ x: x, y: y });

}

​

​

function DrawGrid()

{

  DrawMinorLines();

  DrawMajorLines();

  DrawAxes();

}

​

​

function DrawMinorLines()

{

  stroke(255, 24);

  strokeWeight(2);

  // Non-negative X

  for (let x = floor(width / 2); x <= width; x += gridMinor)

    Line(x, 0, x, height);

  // Negative X

  for (let x = floor(width / 2) - gridMinor; x >= 0; x -= gridMinor)

    Line(x, 0, x, height);

  // Non-negative Y

  for (let y = floor(height / 2); y <= height; y += gridMinor)

    Line(0, y, width, y);

  // Negative Y

  for (let y = floor(height / 2) - gridMinor; y >= 0; y -= gridMinor)

    Line(0, y, width, y);

}

​

​

function DrawMajorLines()

{

  stroke(255, 64);

  strokeWeight(2);

  // Non-negative X

  for (let x = floor(width / 2); x <= width; x += gridMajor)

    Line(x, 0, x, height);

  // Negative X

  for (let x = floor(width / 2) - gridMajor; x >= 0; x -= gridMajor)

    Line(x, 0, x, height);

  // Non-negative Y

  for (let y = floor(height / 2); y <= height; y += gridMajor)

    Line(0, y, width, y);

  // Negative Y

  for (let y = floor(height / 2) - gridMajor; y >= 0; y -= gridMajor)

    Line(0, y, width, y);

}

​

​

function DrawAxes()

{

  stroke(255, 128);

  strokeWeight(2);

  // X axis

  Line(0, halfH, width, halfH);

  // Y axis

  Line(halfW, 0, halfW, height);

}

​

​

function DrawAllPoints()

{

  stroke(255);

  strokeWeight(2 * r);

  for (const p of points)

    DrawPoint(p);

}

​

​

function DrawPoint(p)

{

  Point(p.x + halfW, halfH - p.y);

}

​

​

function DrawArithmeticMean()

{

  if (points.length <= 1) return;

  stroke(100, 140, 250);

  strokeWeight(2 * r);

  let x = 0;

  let y = 0;

  for (const p of points)

  {

    x += p.x;

    y += p.y;

  }

  x /= points.length;

  y /= points.length;

  DrawPoint({ x: x, y: y });

}

​

​

function DrawGeometricMean()

{

  if (points.length <= 1) return;

  stroke(250, 40, 80);

  strokeWeight(2 * r);

  let x = 1;

  let y = 1;

  for (const p of points)

  {

    x *= p.x;

    y *= p.y;

  }

  x = pow(x, 1 / points.length);

  y = pow(y, 1 / points.length);

  DrawPoint({ x: x, y: y });

}

​

​

function Line(x0, y0, x1, y1)

{

  let f = 0.0;

  line(x0 + f, y0 + f, x1 + f, y1 + f);

}

​

​

function Point(x0, y0)

{

  let f = 0.5;

  point(x0 + f, y0 + f);

}

​