disjoiner

Split a set of valued intervals into disjoint intervals. Useful for computing occupancy in overlapping schedules.

Installing

Using npm

npm install disjoiner

Using yarn

yarn add disjoiner

Import in typescript using

import { Disjoiner } from 'disjoiner';

Import in node.js using

const Disjoiner = require('disjoiner').Disjoiner;

Example

Example using typescript

import { Disjoiner } from 'disjoiner';

// Specify how to disjoin the intervals
const disjoiner = new Disjoiner<Date, number>({

  // Specify how to compare two dates
  // Same type of compare function that is used in Array.sort
  // (see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort)
  compare: (obj1, obj2) => obj1.getTime() - obj2.getTime(),

  // Set how to merge two values of overlapping intervals
  // For example add the values
  mergeValues: (val1, val2) => val1 + val2,

  // Check if two values are equal
  // Used to merge intervals
  equals: (val1, val2) => val1 === val2
});

// Some example intervals
const intervals = [{
  start: new Date('2020-01-01'),
  end: new Date('2020-06-01'),
  value: 10
}, {
  start: new Date('2020-03-01'),
  end: new Date('2020-04-05'),
  value: 20
}, {
  start: new Date('2020-01-01'),
  end: new Date('2020-07-01'),
  value: 10
}];

// Run disjoiner
const disjointIntervals = disjoiner.disjoin(intervals);

// Outputs an array with intervals where the value for each time is known
// [{
//   start: new Date('2020-01-01'),
//   end: new Date('2020-03-01'),
//   value: 20
// }, {
//   start: new Date('2020-03-01'),
//   end: new Date('2020-04-05'),
//   value: 40
// }, {
//   start: new Date('2020-04-05'),
//   end: new Date('2020-06-01'),
//   value: 20
// }, {
//   start: new Date('2020-06-01'),
//   end: new Date('2020-07-01'),
//   value: 10
// }]

Documentation

Disjoiner<K, V>

Class that converts an array of valued intervals to an array of disjoint intervals. The generic type K specifies the type of the interval start and end, while the generic type V specifies the type of the value.

• new Disjoiner<K, V>(config: DisjoinerConfig<K, V>) Constructs a disjoiner.
• disjoin(items: ValuedIntervals<K, V>[]): ValuedInterval<K, V>[] Takes an array of valued intervals and converts it to an array of disjoint intervals.

DisjoinerConfig<K, V>

Config for the disjoiner constructor.

• compare(obj1: K, obj2: K): number A compareator functions for the interval range limits obj1 and obj2. The result should be negative if obj1 < obj2, zero if obj1 === obj2, and positive if obj1 > obj2. This function works the same was as the compare function in Array.sort (see MDN).
• mergeValues(val1: V, val2: V): V Specify how values should be merged when two intervals overlap. The simplest function is to add the values. Note that this function should be associative and commutative to give a well defined output.
• equals(val1: V, val2: V): boolean Checks if two values are equal. This function is used to merge intervals next to each other where the values are the same. To turn off this functionality always return false.

ValuedInterval<K, V>

An interval with a value.

• start: K The start of the interval (e.g. a date specifying the start of an event).
• end: K The end of the interval (e.g. a date specifying the end of an event).
• value: V The value of the interval (e.g. salary per hour during this interval).

License

MIT