Static interval tree

A very simple library for finding overlapping intervals in one dimension.

The intervals are indexed using an augmented balanced binary search tree. The search tree is bulk-loaded by sorting. There's no support for adding/removing intervals.

Intervals are assumed to be over integers. Coordinates can be closed [start, end], or half-open [start, end).

Query time with the index should be O(log n + k), (k being number of matches returned) rather than the O(n) required for a brute-force search.

Work in progress. Might be useful for drawing genomic data.

Methods

var {index, matches} = require('static-interval-tree');
 
// index(intervals :: [{start, end, ...}, ...]) :: interval-tree
 
var idx = index([{start: 10, end: 12, id: 1}, {start: 21, end: 30: id: 2}]);
 
// matches(interval-tree, pos :: {start, end}) :: [{start, end, ...}, ...]
 
var overlapping = matches(idx, {start: 12, end: 22});
// => [{start: 10, end: 12, id: 1}, {start: 21, end: 30: id: 2}]
 
// matching half-open coords, [start, end)
// matches01(interval-tree, pos :: {start, end}) :: [{start, end, ...}, ...]
 
var overlapping = matches01(idx, {start: 12, end: 22});
// => [{start: 21, end: 30: id: 2}]
 

Note that building the tree is independent of the choice of closed or half-open coordinates, however you should use match01 if your coordinates are half-open. The intervals in the tree and the interval for query must use the same coordinate system, either closed or half-open.

Build

The build is based on npm and webpack.

• Ensure that git and node are installed
  • On OSX, install brew http://brew.sh/
  • brew install git
  • brew install node
• git clone https://github.com/acthp/static-interval-tree.git
• cd static-interval-tree
• npm install
• npm start
• browse to http://localhost:8080/webpack-dev-server/

Lint

Use npm run lint to run the lint rules. We lint with eslint and babel-eslint.

References

• http://blog.keithcirkel.co.uk/how-to-use-npm-as-a-build-tool/
• http://webpack.github.io/
• http://www.youtube.com/watch?v=VkTCL6Nqm6Y