[][src]Trait vpsearch::MetricSpace

pub trait MetricSpace<UserImplementationType = ()> {
    type UserData;
    type Distance: Copy + PartialOrd + Bounded + Add<Output = Self::Distance>;
    fn distance(
        other: &Self,
        user_data: &Self::UserData
    ) -> Self::Distance; }

Elements you're searching for must be comparable using this trait.

You can ignore UserImplementationType if you're implementing MetricSpace for your custom type. However, if you're implementing MetricSpace for a type from std or another crate, then you need to uniquely identify your implementation (that's because of Rust's Orphan Rules).

This example is not tested
impl MetricSpace for MyInt {/*…*/}

/// That dummy struct disambiguates between yours and everyone else's impl for a tuple:
struct MyXYCoordinates;
impl MetricSpace<MyXYCoordinates> for (f32,f32) {/*…*/}

Associated Types

type UserData

This is used as a context for comparisons. Use () if the elements already contain all the data you need.

type Distance: Copy + PartialOrd + Bounded + Add<Output = Self::Distance>

This is a fancy way of saying it should be f32 or u32

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Required methods

fn distance(&self, other: &Self, user_data: &Self::UserData) -> Self::Distance

This function must return distance between two items that meets triangle inequality. Specifically, it MUST NOT return a squared distance (you must use sqrt if you use Euclidean distance)

  • user_data —Whatever you want. Passed from new_with_user_data_*()
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