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. Archery is available for Scala 2.10 and Scala 2.11.

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

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

libraryDependencies += "com.meetup" %% "archery" % "0.4.0"

For Maven or Ivy, you'll use the same resolver URL but you'll need a slightly different artifact name (the example is for Scala 2.11):

org=com.meetup
name=archery_2.11
rev=0.4.0

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

If you find something that seems like a bug in Archery, or see confusing behavior, or find a place where the documentation or library could be better, please open an issue.

Pull requests are gladly accepted. The preferred strategy is to open an issue or pull request where the feature can be discussed. We can use the PR to collaborate on, and will merge it once everyone agrees on the change, the tests and docs are updated, etc.

Building Archery

Building this project requires SBT 0.13.x.

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

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

(Travis automatically runs test and scalastyle, so any issues should also be detected when a pull request is opened.)

You can generate coverage statistics manually by running the following command from the command-line:

$ sbt clean coverage test coverageReport

Open core/target/scala-2.11/scoverage-report/index.html in a web browser to see local coverage.

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

Test coverage is measured using sbt-scoverage and tracked at codecov.io.

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) 2013-2015 Meetup Inc.