Archery

Overview

Archery is a two-dimensional R-Tree written in Scala. The implementation is immutable: adding and removing points from the tree produces a new tree, leaving the old one untouched. Due to structural sharing this operation is quite efficient.

The name "archery" is a corruption of the word "R-Tree".

Getting Archery

Archery is published to bintray using the bintray-sbt plugin.

If you use SBT, you can include Archery via the following build.sbt snippets:

resolvers += "bintray/meetup" at "http://dl.bintray.com/meetup/maven"

libraryDependencies += "com.meetup" %% "archery" % "0.1.0"

For Maven or Ivy, you'll use the same resolver URL but you'll need to use a slightly different artifact name:

org=com.meetup
name=archery_2.10
rev=0.1.0

Archery is currently published against Scala 2.10, although a future release may include 2.9 support as well.

Example Usage

import archery._

// create some entries
val alice = Entry(Point(9.12F, -4.9F), "alice")
val bob = Entry(Point(2.3F, 4.6F), "bob")
val candice = Entry(Point(4.7F, -1.9F), "candice")
val doug = Entry(Point(5.5F, -3.2F), "doug")

// build a tree with three points
val tree1: RTree[String] = RTree(alice, bob, candice)

// add "doug"
val tree2: RTree[String] = tree1.insert(doug)

// remove "bob"
val tree3: RTree[String] = tree2.remove(bob)

// search from (0,-4) to (10,6), will find "doug"
val bbox: Box = Box(0F, -4F, 10F, 6F)
val results: Seq[Entry[String]] = tree3.search(bbox)

// we can also just ask how many matching entries exist
val n: Int = tree3.count(bbox)
assert(results.length == n)

Contributing

Building this project requires SBT 0.13.0.

After you launch SBT, you can run the following commands:

• compile compile the project
• core/test run the tests
• benchmark/run run the included timing benchmarks
• console load a scala REPL with archery on the classpath.

Tests are written with ScalaTest and use the excellent ScalaCheck library for automated specification-based testing.

The benchmarks are written against Rex Kerr's excellent library Thyme.

License

Archery is available to you under the MIT license. See the COPYING file for details.

Credits

Archery is maintained by Erik Osheim.

Copyright (c) 2013 Meetup Inc.