Port to safe Rust of [cheap-ruler] and [cheap-ruler-cpp], a collection of very fast approximations to common geodesic measurements.
The approximations are based on WGS84 and its ellipsoidal model of the Earth. The results of calculations are accurate to small differences of the latitude provided at construction, and are less computationally expensive.
See [cheap-ruler]'s readme for accuracy claims compared to the Vincenty formulas.
Here's example program to print the distance and bearing between two points:
```rust extern crate cheap_ruler;
use cheap_ruler::{CheapRuler, DistanceUnit};
fn main() { let ruler = CheapRuler::new(44.7192003, DistanceUnit::Meters); let p1 = point!(x: 14.8901816, y: 44.7209699); let p2 = point!(x: 14.8905188, y: 44.7209699);
let dist = ruler.distance(&p1, &p2); let bearing = ruler.bearing(&p1, &p2);
println!("Distance between points: {}", dist); println!("Bearing: {}", bearing); } ```
This Rust port additionally allows the distance unit of the ruler to be changed and retrieved at any point after construction at the cost of larger memory size of the ruler struct itself (40 bytes instead of 16 bytes), but with no additional overhead.
```rust extern crate cheapruler; use cheapruler::{CheapRuler, DistanceUnit};
fn main() { let mut ruler = CheapRuler::new(44.7192003, DistanceUnit::Meters); println!("Distance unit: {:?}", ruler.distance_unit());
ruler.changeunit(DistanceUnit::Miles); println!("Distance unit: {:?}", ruler.distanceunit()); } ```
The library uses the geo-types crate for representation of points and
coordinates. The one exception are the BBox functions, which use a custom Rect
implementation that does not automatically swap min/max bounds:
```rust extern crate cheap_ruler;
use cheapruler::{CheapRuler, DistanceUnit, Rect}; use geotypes::{Coordinate};
fn main() { let ruler = CheapRuler::new(32.8351, DistanceUnit::Kilometers); let bbox = Rect::new( Coordinate { x: 179.9, y: 32.7 }, Coordinate { x: -179.9, y: 32.9 }, ); let p = point!(x: 180.0, y: 32.8); assert!(ruler.inside_bbox(&p, &bbox)); } ```
Cheap ruler's distance calculation is about 16 times faster than the [geo] crate's haversine algorithm implementation (times below are from a machine with Intel Core i7-8550U).
distance/cheap_ruler time: [291.10 ps 292.38 ps 293.89 ps]
distance/haversine time: [4.7215 ns 4.8545 ns 5.0086 ns]
distance/vincenty time: [315.83 ns 320.75 ns 325.93 ns]
See the [CHANGELOG] file for details.
This library is licensed under the ISC License. See the [LICENSE] file for the full license content.