Add Calculate, Hamerly impls for [T; N]

Cargo.toml

@@ -3,7 +3,7 @@ name = "kmeans_colors"
 version = "0.6.0"
 authors = ["okaneco <47607823+okaneco@users.noreply.github.com>"]
 edition = "2018"
-exclude = ["test", "gfx", ".github"]
+exclude = ["test", "gfx", ".github", "examples"]
 homepage = "https://github.com/okaneco/kmeans-colors"
 repository = "https://github.com/okaneco/kmeans-colors"
 readme = "README.md"
@@ -25,7 +25,7 @@ app = [
     ]
 
 # Enable `palette` color types
-palette_color = ["palette", "num-traits"]
+palette_color = ["palette"]
 
 [dependencies.image]
 version = "0.24.6"
@@ -43,7 +43,6 @@ optional = true
 version = "0.2.16"
 default-features = false
 features = ["std"]
-optional = true
 
 [dependencies.rand]
 version = "0.8.5"

src/colors/kmeans.rs

@@ -1,8 +1,7 @@
 #[cfg(feature = "palette_color")]
-use num_traits::{Float, FromPrimitive, Zero};
-#[cfg(feature = "palette_color")]
 use palette::{rgb::Rgb, rgb::Rgba, Lab};
 
+use num_traits::{Float, FromPrimitive, Zero};
 use rand::Rng;
 
 use crate::kmeans::{Calculate, Hamerly, HamerlyCentroids, HamerlyPoint};

src/kmeans.rs

@@ -1,5 +1,7 @@
 use rand::{Rng, SeedableRng};
 
+mod array;
+
 /// A trait for enabling k-means calculation of a data type.
 pub trait Calculate: Sized {
     /// Find a points's nearest centroid, index the point with that centroid.

src/kmeans/array.rs

@@ -0,0 +1,216 @@
+use core::ops::{AddAssign, DivAssign};
+
+use num_traits::{Float, FromPrimitive};
+
+use crate::{Calculate, Hamerly};
+
+impl<T, const N: usize> Calculate for [T; N]
+where
+    T: Float + FromPrimitive + AddAssign + DivAssign + Default,
+    [T; N]: Default,
+{
+    fn get_closest_centroid(buffer: &[Self], centroids: &[Self], indices: &mut Vec<u8>) {
+        indices.extend(buffer.iter().map(|color| {
+            let mut index = 0;
+            let mut diff;
+            let mut min = core::f32::MAX;
+            for (idx, cent) in centroids.iter().enumerate() {
+                diff = Self::difference(color, cent);
+                if diff < min {
+                    min = diff;
+                    index = idx;
+                }
+            }
+            index as u8
+        }))
+    }
+
+    fn recalculate_centroids(
+        rng: &mut impl rand::Rng,
+        buf: &[Self],
+        centroids: &mut [Self],
+        indices: &[u8],
+    ) {
+        for (idx, cent) in centroids.iter_mut().enumerate() {
+            let mut acc = Self::default();
+            let mut counter: u64 = 0;
+            for (&jdx, &color) in indices.iter().zip(buf) {
+                if jdx as usize == idx {
+                    acc.iter_mut().zip(color.iter()).for_each(|(t, &c)| *t += c);
+                    counter += 1;
+                }
+            }
+            if counter != 0 {
+                let counter_float = T::from_f64(counter as f64).unwrap();
+                acc.iter_mut().for_each(|t| *t /= counter_float);
+                *cent = acc;
+            } else {
+                *cent = Self::create_random(rng);
+            }
+        }
+    }
+
+    fn check_loop(centroids: &[Self], old_centroids: &[Self]) -> f32 {
+        let mut acc = Self::default();
+        for (new_cent, old_cent) in centroids.iter().zip(old_centroids) {
+            acc.iter_mut()
+                .zip(new_cent.iter())
+                .zip(old_cent.iter())
+                .for_each(|((t, &new), &old)| *t += new - old);
+        }
+
+        acc.iter()
+            .fold(T::default(), |accum, t| accum + t.powi(2))
+            .to_f32()
+            .unwrap_or(f32::MAX)
+    }
+
+    // 2023-08 TODO: create_random should take a min and max from a builder object
+    fn create_random(rng: &mut impl rand::Rng) -> Self {
+        let mut out = Self::default();
+        out.iter_mut()
+            .for_each(|o| *o = T::from_f64(rng.gen_range(0.0..=1.0)).unwrap());
+        out
+    }
+
+    fn difference(c1: &Self, c2: &Self) -> f32 {
+        c1.iter()
+            .zip(c2.iter())
+            .fold(T::default(), |acc, (&l, &r)| acc + (l - r).powi(2))
+            .to_f32()
+            .unwrap_or(f32::MAX)
+    }
+}
+
+impl<T, const N: usize> Hamerly for [T; N]
+where
+    T: Float + FromPrimitive + AddAssign + DivAssign + Default,
+    [T; N]: Default,
+{
+    fn compute_half_distances(centroids: &mut crate::HamerlyCentroids<Self>) {
+        // Find each center's closest center
+        for ((i, ci), half_dist) in centroids
+            .centroids
+            .iter()
+            .enumerate()
+            .zip(centroids.half_distances.iter_mut())
+        {
+            let mut diff;
+            let mut min = f32::MAX;
+            for (j, cj) in centroids.centroids.iter().enumerate() {
+                // Don't compare centroid to itself
+                if i == j {
+                    continue;
+                }
+                diff = Self::difference(ci, cj);
+                if diff < min {
+                    min = diff;
+                }
+            }
+            *half_dist = min.sqrt() * 0.5;
+        }
+    }
+
+    fn get_closest_centroid_hamerly(
+        buffer: &[Self],
+        centroids: &crate::HamerlyCentroids<Self>,
+        indices: &mut [crate::HamerlyPoint],
+    ) {
+        for (val, point) in buffer.iter().zip(indices.iter_mut()) {
+            // Assign max of lower bound and half distance to z
+            let z = centroids
+                .half_distances
+                .get(point.index as usize)
+                .unwrap()
+                .max(point.lower_bound);
+
+            if point.upper_bound <= z {
+                continue;
+            }
+
+            // Tighten upper bound
+            point.upper_bound =
+                Self::difference(val, centroids.centroids.get(point.index as usize).unwrap())
+                    .sqrt();
+
+            if point.upper_bound <= z {
+                continue;
+            }
+
+            // Find the two closest centers to current point and their distances
+            if centroids.centroids.len() < 2 {
+                continue;
+            }
+
+            let mut min1 = Self::difference(val, centroids.centroids.get(0).unwrap());
+            let mut min2 = f32::MAX;
+            let mut c1 = 0;
+            for j in 1..centroids.centroids.len() {
+                let diff = Self::difference(val, centroids.centroids.get(j).unwrap());
+                if diff < min1 {
+                    min2 = min1;
+                    min1 = diff;
+                    c1 = j;
+                    continue;
+                }
+                if diff < min2 {
+                    min2 = diff;
+                }
+            }
+
+            if c1 as u8 != point.index {
+                point.index = c1 as u8;
+                point.upper_bound = min1.sqrt();
+            }
+            point.lower_bound = min2.sqrt();
+        }
+    }
+
+    fn recalculate_centroids_hamerly(
+        rng: &mut impl rand::Rng,
+        buf: &[Self],
+        centroids: &mut crate::HamerlyCentroids<Self>,
+        points: &[crate::HamerlyPoint],
+    ) {
+        for ((idx, cent), delta) in centroids
+            .centroids
+            .iter_mut()
+            .enumerate()
+            .zip(centroids.deltas.iter_mut())
+        {
+            let mut acc = Self::default();
+            let mut counter: u64 = 0;
+            for (point, &color) in points.iter().zip(buf) {
+                if point.index as usize == idx {
+                    acc.iter_mut().zip(color.iter()).for_each(|(t, &c)| *t += c);
+                    counter += 1;
+                }
+            }
+            if counter != 0 {
+                let counter_float = T::from_f64(counter as f64).unwrap();
+                acc.iter_mut().for_each(|t| *t /= counter_float);
+            } else {
+                acc = Self::create_random(rng);
+            }
+            *delta = Self::difference(cent, &acc).sqrt();
+            *cent = acc;
+        }
+    }
+
+    fn update_bounds(
+        centroids: &crate::HamerlyCentroids<Self>,
+        points: &mut [crate::HamerlyPoint],
+    ) {
+        let mut delta_p = 0.0;
+        for &c in centroids.deltas.iter() {
+            if c > delta_p {
+                delta_p = c;
+            }
+        }
+
+        points.iter_mut().for_each(|point| {
+            point.upper_bound += centroids.deltas.get(point.index as usize).unwrap();
+            point.lower_bound -= delta_p;
+        })
+    }
+}