Kiddo

A high-performance, flexible, ergonomic k-d tree library.

Kiddo is ideal for super-fast spatial / geospatial lookups and nearest-neighbour / KNN queries for low-ish numbers of dimensions, where you want to ask questions such as: - Find the nearest_n item(s) to a query point, ordered by distance; - Find all items within a specified radius of a query point; - Find the "best" n item(s) within a specified distance of a query point, for some definition of "best"

Differences vs Kiddo v1.x

Version 2.x is a complete rewrite, providing: - a new internal architecture for much-improved performance; - Added integer / fixed point support via the Fixed library; - instant zero-copy deserialization and serialization via Rkyv (Serde still available). - See the changelog for a detailed run-down on all the changes made in v2.

Usage

Add kiddo to Cargo.toml toml [dependencies] kiddo = "2.0.0-beta.5"

Add points to kdtree and query nearest n points with distance function ```rust use kiddo::KdTree; use kiddo::distance::squared_euclidean;

let entries = vec![ [0f64, 0f64], [1f64, 1f64], [2f64, 2f64], [3f64, 3f64] ];

// use the kiddo::KdTree type to get up and running quickly with default settings let mut kdtree: KdTree<_, 2> = (&entries).into();

// How many items are in tree? assert_eq!(kdtree.size(), 4);

// find the nearest item to [0f64, 0f64]. // returns a tuple of (dist, index) asserteq!( kdtree.nearestone(&[0f64, 0f64], &squared_euclidean), (0f64, 0) );

// find the nearest 3 items to [0f64, 0f64], and collect into a Vec asserteq!( kdtree.nearestn(&[0f64, 0f64], 3, &squared_euclidean).collect::>(), vec![(0f64, 0), (2f64, 1), (8f64, 2)] ); ``` See the examples documentation for some more detailed examples.

Benchmarks

Criterion is used to perform a series of benchmarks. We compare Kiddo v2 to: - Kiddo v1 - kdtree - FNNTW - pykdtree

Each action is benchmarked against trees that contain 100, 1,000, 10,000, 100,000, 1,000,000 and in some cases 10,000,000 nodes and charted below.

The Adding Items benchmarks are repeated against 2d, 3d and 4d trees. The 3d benchmarks are ran with points that are both of type f32 and of type f64, as well as a 16-bit fixed point use case.

All of the remaining tests are only performed against 3d trees, for expediency. The trees are populated with random source data whose points are all on a unit sphere. This use case is representative of common kd-tree usages in geospatial and astronomical contexts.

The Nearest n Items tests query the tree for the nearest 1, 100 and 1,000 points at each tree size. The test for the common case of the nearest one point uses kiddo's nearest_one() method, which is an optimised method for this specific common use case.

Benchmarking Methodology

NB: This section is out-of-date and pertains to kiddo v1. I'll update it soon.

The results and charts below were created via the following process:

bash cargo criterion --message-format json > criterion-kdtree.ndjson

bash cargo criterion --message-format json --all-features > criterion-kiddo.ndjson

bash python ./generate_benchmark_charts.py

Benchmarking Results

Updated benchmark results will be published soon.

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.