Heatmap

Heatmaps for node.js and the browser!

Example

blob.js

const Heatmap = require("heatmap");
const fs = require("fs");
const heat = new Heatmap(500, 500, { radius: 30 });

for (let i = 0; i < 5000; i += 1) {
  let rho = Math.random() * 2 * Math.PI;
  let z = Math.pow(Math.random(), 2) * 200;

  let x = 250 + Math.cos(rho) * z;
  let y = 250 + Math.sin(rho) * z;

  heat.addPoint(x, y);
}

heat.draw();

fs.writeFileSync("blob.png", heat.canvas.toBuffer());

Methods

var heat = new Heatmap(...)

There are two ways of creating a new heatmap:

• With the id of the target canvas element
• With the height and width values for the canvas element to be created

Optionally, you can set the opts.radius and opts.threshold to control the rendering a little.

heat.addPoint(x, y, params)

Add a point to the heatmap with a radius.

params must be an object and can have:

• radius, defaults to heat.radius || 20
• weight, defaults to 0.1

heat.scale(x, y)

Scale the canvas by the coefficients x and y.

If y is undefined, scale both x and y by the first parameter, x.

heat.draw()

Render all the points onto the canvas element.

heat.canvas

The HTML Canvas element.

Protip: with the canvas module for node you can heat.canvas.buffer() to get a Buffer with a PNG file all up in it.

Install

With npm, just do:

npm install heatmap-pkg

Or with yarn:

yarn add heatmap-pkg