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authorTavian Barnes <tavianator@tavianator.com>2020-06-24 15:20:02 -0400
committerTavian Barnes <tavianator@tavianator.com>2020-06-24 15:44:14 -0400
commit39c0348c9f98b4dd29bd112a0a2a42faa67c92d4 (patch)
tree6c8ed80bd8cbbb0af79c9ac57bdb39634fa178fd /src/metric/vp.rs
parentadaafdd7043507cbceae65e78c38954e47103b5c (diff)
downloadkd-forest-master.tar.xz
Use the acap nearest neighbors implementationHEADmaster
Diffstat (limited to 'src/metric/vp.rs')
-rw-r--r--src/metric/vp.rs137
1 files changed, 0 insertions, 137 deletions
diff --git a/src/metric/vp.rs b/src/metric/vp.rs
deleted file mode 100644
index d6e05df..0000000
--- a/src/metric/vp.rs
+++ /dev/null
@@ -1,137 +0,0 @@
-//! [Vantage-point trees](https://en.wikipedia.org/wiki/Vantage-point_tree).
-
-use super::{Metric, NearestNeighbors, Neighborhood, Ordered};
-
-use std::iter::FromIterator;
-
-/// A node in a VP tree.
-#[derive(Debug)]
-struct VpNode<T> {
- /// The vantage point itself.
- item: T,
- /// The radius of this node.
- radius: f64,
- /// The size of the subtree inside the radius.
- inside_len: usize,
-}
-
-impl<T: Metric> VpNode<T> {
- /// Create a new VpNode.
- fn new(item: T) -> Self {
- Self {
- item,
- radius: 0.0,
- inside_len: 0,
- }
- }
-
- /// Build a VP tree recursively.
- fn build(slice: &mut [VpNode<T>]) {
- if let Some((node, children)) = slice.split_first_mut() {
- let item = &node.item;
- children.sort_by_cached_key(|n| Ordered(item.distance(&n.item)));
-
- let (inside, outside) = children.split_at_mut(children.len() / 2);
- if let Some(last) = inside.last() {
- node.radius = item.distance(&last.item).into();
- }
- node.inside_len = inside.len();
-
- Self::build(inside);
- Self::build(outside);
- }
- }
-
- /// Recursively search for nearest neighbors.
- fn recurse<'a, U, N>(slice: &'a [VpNode<T>], neighborhood: &mut N)
- where
- T: 'a,
- U: Metric<&'a T>,
- N: Neighborhood<&'a T, U>,
- {
- let (node, children) = slice.split_first().unwrap();
- let (inside, outside) = children.split_at(node.inside_len);
-
- let distance = neighborhood.consider(&node.item).into();
-
- if distance <= node.radius {
- if !inside.is_empty() && neighborhood.contains(distance - node.radius) {
- Self::recurse(inside, neighborhood);
- }
- if !outside.is_empty() && neighborhood.contains(node.radius - distance) {
- Self::recurse(outside, neighborhood);
- }
- } else {
- if !outside.is_empty() && neighborhood.contains(node.radius - distance) {
- Self::recurse(outside, neighborhood);
- }
- if !inside.is_empty() && neighborhood.contains(distance - node.radius) {
- Self::recurse(inside, neighborhood);
- }
- }
- }
-}
-
-/// A [vantage-point tree](https://en.wikipedia.org/wiki/Vantage-point_tree).
-#[derive(Debug)]
-pub struct VpTree<T>(Vec<VpNode<T>>);
-
-impl<T: Metric> FromIterator<T> for VpTree<T> {
- fn from_iter<I: IntoIterator<Item = T>>(items: I) -> Self {
- let mut nodes: Vec<_> = items.into_iter().map(VpNode::new).collect();
- VpNode::build(nodes.as_mut_slice());
- Self(nodes)
- }
-}
-
-impl<T, U> NearestNeighbors<T, U> for VpTree<T>
-where
- T: Metric,
- U: Metric<T>,
-{
- fn search<'a, 'b, N>(&'a self, mut neighborhood: N) -> N
- where
- T: 'a,
- U: 'b,
- N: Neighborhood<&'a T, &'b U>,
- {
- if !self.0.is_empty() {
- VpNode::recurse(&self.0, &mut neighborhood);
- }
-
- neighborhood
- }
-}
-
-/// An iterator that moves values out of a VP tree.
-#[derive(Debug)]
-pub struct IntoIter<T>(std::vec::IntoIter<VpNode<T>>);
-
-impl<T> Iterator for IntoIter<T> {
- type Item = T;
-
- fn next(&mut self) -> Option<T> {
- self.0.next().map(|n| n.item)
- }
-}
-
-impl<T> IntoIterator for VpTree<T> {
- type Item = T;
- type IntoIter = IntoIter<T>;
-
- fn into_iter(self) -> Self::IntoIter {
- IntoIter(self.0.into_iter())
- }
-}
-
-#[cfg(test)]
-mod tests {
- use super::*;
-
- use crate::metric::tests::test_nearest_neighbors;
-
- #[test]
- fn test_vp_tree() {
- test_nearest_neighbors(VpTree::from_iter);
- }
-}