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use num_traits::FromPrimitive;
use crate::vincenty_distance::{FailedToConvergeError, VincentyDistance};
use crate::{CoordFloat, Line, LineString, MultiLineString};
/// Determine the length of a geometry using [Vincenty’s formulae].
///
/// [Vincenty’s formulae]: https://en.wikipedia.org/wiki/Vincenty%27s_formulae
pub trait VincentyLength<T, RHS = Self> {
/// Determine the length of a geometry using [Vincenty’s formulae].
///
/// # Units
///
/// - return value: meters
///
/// # Examples
///
/// ```
/// use geo::prelude::*;
/// use geo::LineString;
///
/// let linestring = LineString::<f64>::from(vec![
/// // New York City
/// (-74.006, 40.7128),
/// // London
/// (-0.1278, 51.5074),
/// // Osaka
/// (135.5244559, 34.687455)
/// ]);
///
/// let length = linestring.vincenty_length().unwrap();
///
/// assert_eq!(
/// 15_109_158., // meters
/// length.round()
/// );
/// ```
///
/// [Vincenty’s formulae]: https://en.wikipedia.org/wiki/Vincenty%27s_formulae
fn vincenty_length(&self) -> Result<T, FailedToConvergeError>;
}
impl<T> VincentyLength<T> for Line<T>
where
T: CoordFloat + FromPrimitive,
{
/// The units of the returned value is meters.
fn vincenty_length(&self) -> Result<T, FailedToConvergeError> {
let (start, end) = self.points();
start.vincenty_distance(&end)
}
}
impl<T> VincentyLength<T> for LineString<T>
where
T: CoordFloat + FromPrimitive,
{
fn vincenty_length(&self) -> Result<T, FailedToConvergeError> {
let mut length = T::zero();
for line in self.lines() {
length = length + line.vincenty_length()?;
}
Ok(length)
}
}
impl<T> VincentyLength<T> for MultiLineString<T>
where
T: CoordFloat + FromPrimitive,
{
fn vincenty_length(&self) -> Result<T, FailedToConvergeError> {
let mut length = T::zero();
for line_string in &self.0 {
length = length + line_string.vincenty_length()?;
}
Ok(length)
}
}