Automatic scatter labelling

Compute the positions of labels in a scatter plot. It implements the NOLOOKAHEAD algorithm described in:

Theophil S., Schödl A. An Efficient Algorithm for Scatter Chart Labeling AAAI

Install

$ npm install --save automatic-scatter-labelling

It requires of a webworker so right now it only works for the browser.

Example

Running npm run gulp will launch a full working example in the browser

Basic usage

With browserify or webpack

const algorithm = require('automatic-scatter-labelling')
const pointsToLabel = [
  {id: 1,
  position: {
    x: 10,
    y: -20
    },
  label: {
    height: 30,
    width: 20
    }
  },
  {
    id: 2,
    position: {
      x: 10,
      y: -20
    },
  label: {
    height: 30,
    width: 20
  }
]

mainAlgorithm(pointsToLabel)
  .then(function (rectangles) {
    const rectangle = rectangles[0]
    const id = rectangle.id // Corresponding to the id provided in the algorithm
    // Coordinates to place the rectangle 
    const {left, right, top, bottom} = rectangle.rectangle
  })

Advanced usage

Additionally to the points we want to label we can provide extra arguments to tweak the algorithm. radius is used to indicate that some space should be left around the points. bbox to indicate where the labels should be restricted (so that they don't go offscreen).

Example:

  const result = await algorithm(pointsToLabel, {
    radius: 5,
    bbox: {
      top: margin.top,
      bottom: -margin.top + height,
      left: margin.left,
      right: margin.left + width,
      width,
      height: height
    }
  })