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https://github.com/ben-ng/swift-range-tree
Orthogonal range searches in polylog time
https://github.com/ben-ng/swift-range-tree
Last synced: 21 days ago
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Orthogonal range searches in polylog time
- Host: GitHub
- URL: https://github.com/ben-ng/swift-range-tree
- Owner: ben-ng
- License: mit
- Created: 2016-09-17T18:02:01.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2016-09-24T18:44:44.000Z (about 8 years ago)
- Last Synced: 2024-10-10T19:03:26.902Z (28 days ago)
- Language: Swift
- Homepage:
- Size: 43 KB
- Stars: 3
- Watchers: 3
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# RangeTree
[](https://travis-ci.org/ben-ng/swift-range-tree)
[](http://cocoapods.org/pods/RangeTree)
[](http://cocoapods.org/pods/RangeTree)
[](http://cocoapods.org/pods/RangeTree)
A range tree allows you to perform orthorgonal range searches in polylogarithmic time. i.e. If you had a bunch of points in two-dimensional space, and you want to quickly figure out what points have an x coordinate between a and b, and a y coordinate between c and d, this is the module for you.
This module implements an n-dimensional range tree. You define how many dimensions you need by implementing the `RangeTreePoint` protocol. Note that you will see a performance penalty versus a naive `Array.filter` if your dataset is too small. See the section on [performance](#performance) to gauge if your dataset is large enough to benefit from this data structure.
## Usage
1. Implement the `RangeTreePoint` protocol (it's already implemented on `Int`, `Double`, and `CGPoint` for you as part of this module)
```swift
public protocol RangeTreePoint {
associatedtype Position: Comparable
static var dimensions: Int { get}
func positionIn(dimension: Int) -> Position
}
// Sample implementation
extension CGPoint: RangeTreePoint {
public typealias Position = CGFloat
public static var dimensions = 2
public func positionIn(dimension: Int) -> Position {
return dimension == 0 ? self.x : self.y
}
}
```
2. Construct a RangeTree
```swift
let a = RangeTree(values: [8, 1, 10, 4, 2, 7, 5, 3, 9, 6])
```
3. Query for a range
```swift
a.valuesInRange(rangePerDimension: (3.0, 6.0)) // => [3.0, 4.0, 5.0, 6.0]
```
4. Modify the RangeTree
```swift
a.insert(4.5)
a.valuesInRange(rangePerDimension: (3.0, 6.0)) // => [3.0, 4.0, 4.5, 5.0, 6.0]
```
## Performance
Quad-core 2.8 GHz i7 Retina MacBook Pro:
* Constructing a tree
* 1000 points: 0.133s
* 10000 points: 1.104s
* 100000 points: 8.420s
* 1000000 points: 55.377s
* Querying a tree
* 1000 points: 0.001s (naive `Array.filter`: 0.000s) -- _slower_
* 10000 points: 0.002s (naive `Array.filter`: 0.004s) -- 2x faster
* 100000 points: 0.008s (naive `Array.filter`: 0.029s) - 3.6x faster
* 1000000 points: 0.056s (naive `Array.filter`: 0.266s) - 4.8x faster
1.3 GHz Core m7 12" MacBook:
* Constructing a tree
* 1000 points: 0.206s
* 10000 points: 1.323s
* 100000 points: 10.413s
* 1000000 points: 85.719s
* Querying a tree
* 1000 points: 0.002s (naive `Array.filter`: 0.001s) -- _slower_
* 10000 points: 0.004s (naive `Array.filter`: 0.007s) -- 1.8x faster
* 100000 points: 0.013s (naive `Array.filter`: 0.038s) -- 2.9x faster
* 1000000 points: 0.089s (naive `Array.filter`: 0.436s) -- 4.9x faster
## Example & Tests
To run the example project, clone the repo, and run `pod install` from the Example directory first.
## Installation
RangeTree is available through [CocoaPods](http://cocoapods.org). To install
it, simply add the following line to your Podfile:
```ruby
pod "RangeTree"
```
## Author
Ben Ng, [email protected]
## License
RangeTree is available under the MIT license. See the LICENSE file for more info.