Trait geo::algorithm::map_coords::TryMapCoords

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pub trait TryMapCoords<T, NT, E> {
    type Output;

    fn try_map_coords(
        &self, 
        func: impl Fn(&(T, T)) -> Result<(NT, NT), E> + Copy
    ) -> Result<Self::Output, E>
    where
        T: CoordNum,
        NT: CoordNum;
}

Expand description

Map a fallible function over all the coordinates in a geometry, returning a Result

Required Associated Types

source

type Output

Required Methods

source

fn try_map_coords(
    &self,
    func: impl Fn(&(T, T)) -> Result<(NT, NT), E> + Copy
) -> Result<Self::Output, E> where
    T: CoordNum,
    NT: CoordNum,

Map a fallible function over all the coordinates in a geometry, returning a Result

Examples

use approx::assert_relative_eq;
use geo::algorithm::map_coords::TryMapCoords;
use geo::Point;

let p1 = Point::new(10., 20.);
let p2 = p1
    .try_map_coords(|&(x, y)| -> Result<_, std::convert::Infallible> {
        Ok((x + 1000., y * 2.))
    }).unwrap();

assert_relative_eq!(p2, Point::new(1010., 40.), epsilon = 1e-6);

Advanced Example: Geometry coordinate conversion using `PROJ`

use approx::assert_relative_eq;
// activate the [use-proj] feature in cargo.toml in order to access proj functions
use geo::{Coordinate, Point};
use geo::algorithm::map_coords::TryMapCoords;
use proj::{Coord, Proj, ProjError};
// GeoJSON uses the WGS 84 coordinate system
let from = "EPSG:4326";
// The NAD83 / California zone 6 (ftUS) coordinate system
let to = "EPSG:2230";
let to_feet = Proj::new_known_crs(&from, &to, None).unwrap();
let f = |x: f64, y: f64| -> Result<_, ProjError> {
    // proj can accept Point, Coordinate, Tuple, and array values, returning a Result
    let shifted = to_feet.convert((x, y))?;
    Ok((shifted.x(), shifted.y()))
};
// 👽
let usa_m = Point::new(-115.797615, 37.2647978);
let usa_ft = usa_m.try_map_coords(|&(x, y)| f(x, y)).unwrap();
assert_relative_eq!(6693625.67217475, usa_ft.x(), epsilon = 1e-6);
assert_relative_eq!(3497301.5918027186, usa_ft.y(), epsilon = 1e-6);