@spalger/kibana/src/ui/public/utils/sequencer.js

Kibana is an open source (Apache Licensed), browser based analytics and search dashboard for Elasticsearch. Kibana is a snap to setup and start using. Kibana strives to be easy to get started with, while also being flexible and powerful, just like Elastic

define(function (require) {
  var _ = require('lodash');

  function create(min, max, length, mod) {
    var seq = new Array(length);

    var valueDist = max - min;

    // range of values that the mod creates
    var modRange = [mod(0, length), mod(length - 1, length)];

    // distance between
    var modRangeDist = modRange[1] - modRange[0];

    _.times(length, function (i) {
      var modIPercent = (mod(i, length) - modRange[0]) / modRangeDist;

      // percent applied to distance and added to min to
      // produce value
      seq[i] = min + (valueDist * modIPercent);
    });

    seq.min = min;
    seq.max = max;

    return seq;
  }

  return {
    /**
     * Create an exponential sequence of numbers.
     *
     * Creates a curve resembling:
     *
     *                                                         ;
     *                                                         /
     *                                                        /
     *                                                     .-'
     *                                                 _.-"
     *                                            _.-'"
     *                                      _,.-'"
     *                               _,..-'"
     *                       _,..-'""
     *              _,..-'""
     *  ____,..--'""
     *
     * @param {number} min - the min value to produce
     * @param {number} max - the max value to produce
     * @param {number} length - the number of values to produce
     * @return {number[]} - an array containing the sequence
     */
    createEaseIn: _.partialRight(create, function (i, length) {
      // generates numbers from 1 to +Infinity
      return i * Math.pow(i, 1.1111);
    }),

    /**
     * Create an sequence of numbers using sine.
     *
     * Create a curve resembling:
     *
     *                                            ____,..--'""
     *                                    _,..-'""
     *                            _,..-'""
     *                     _,..-'"
     *               _,.-'"
     *          _.-'"
     *      _.-"
     *   .-'
     *  /
     * /
     * ;
     *
     *
     * @param {number} min - the min value to produce
     * @param {number} max - the max value to produce
     * @param {number} length - the number of values to produce
     * @return {number[]} - an array containing the sequence
     */
    createEaseOut: _.partialRight(create, function (i, length) {
      // adapted from output of http://www.timotheegroleau.com/Flash/experiments/easing_function_generator.htm
      // generates numbers from 0 to 100

      var ts = (i /= length) * i;
      var tc = ts * i;
      return 100 * (
        0.5 * tc * ts +
        -3 * ts * ts +
        6.5 * tc +
        -7 * ts +
        4 * i
      );
    })
  };
});