kiddo 5.0.3

A high-performance, flexible, ergonomic k-d tree library. Ideal for geo- and astro- nearest-neighbour and k-nearest-neighbor queries
Documentation 
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//! A result item returned by a query
use crate::traits::Content;
use std::cmp::Ordering;

/// Represents an entry in the results of a nearest neighbour query, with `distance` being the distance of this
/// particular item from the query point, and `item` being the stored item index that was found
/// as part of the query.
#[derive(Debug, Copy, Clone)]
pub struct NearestNeighbour<A, T> {
    /// the distance of the found item from the query point according to the supplied distance metric
    pub distance: A,
    /// the stored index of an item that was found in the query
    pub item: T,
}

impl<A: PartialOrd, T: Content> Ord for NearestNeighbour<A, T> {
    fn cmp(&self, other: &Self) -> Ordering {
        self.partial_cmp(other).unwrap_or(Ordering::Equal)
    }
}

#[allow(renamed_and_removed_lints)]
#[allow(unknown_lints)]
#[allow(clippy::incorrect_partial_ord_impl_on_ord_type)]
#[allow(clippy::non_canonical_partial_ord_impl)]
impl<A: PartialOrd, T: Content> PartialOrd for NearestNeighbour<A, T> {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        self.distance.partial_cmp(&other.distance)
    }
}

impl<A: PartialEq, T: Content> Eq for NearestNeighbour<A, T> {}

impl<A: PartialEq, T: Content> PartialEq for NearestNeighbour<A, T> {
    fn eq(&self, other: &Self) -> bool {
        self.distance == other.distance && self.item == other.item
    }
}

impl<A, T: Content> From<NearestNeighbour<A, T>> for (A, T) {
    fn from(elem: NearestNeighbour<A, T>) -> Self {
        (elem.distance, elem.item)
    }
}

#[cfg(test)]
mod tests {
    use crate::nearest_neighbour::NearestNeighbour;
    use std::cmp::Ordering;

    #[test]
    fn test_from_tuple() {
        let nn: (f32, usize) = NearestNeighbour::<f32, usize> {
            distance: 1.0f32,
            item: 1usize,
        }
        .into();

        assert_eq!(nn.0, 1.0f32);
        assert_eq!(nn.1, 1usize);
    }

    #[test]
    fn test_partial_cmp() {
        let a = NearestNeighbour {
            distance: 1.0f32,
            item: 10usize,
        };
        let b = NearestNeighbour {
            distance: 2.0f32,
            item: 5usize,
        };

        assert_eq!(a.partial_cmp(&b).unwrap(), Ordering::Less)
    }
}