fix: refactors knn and distance functions

src/math/distance/euclidian.rs

@@ -1,56 +1,33 @@
-use crate::math::distance::Distance;
-use ndarray::{ArrayBase, Data, Dimension};
-use crate::common::AnyNumber;
+pub fn distance(x: &Vec<f64>, y: &Vec<f64>) -> f64 {    
+    return squared_distance(x, y).sqrt();
+}
 
-impl<A, S1, S2, D> Distance<ArrayBase<S2, D>> for ArrayBase<S1, D>
-where
-        A: AnyNumber,
-        S1: Data<Elem = A>,        
-        S2: Data<Elem = A>,        
-        D: Dimension
-{
-    fn distance_to(&self, other: &Self) -> f64 
-    {
-        Self::distance(self, other)
+pub fn squared_distance(x: &Vec<f64>,y: &Vec<f64>) -> f64 {
+    if x.len() != y.len() {
+        panic!("Input vector sizes are different.");
     }
 
-    fn distance(a: &Self, b: &ArrayBase<S2, D>) -> f64 
-    {
-        if a.len() != b.len() {
-            panic!("vectors a and b have different length");
-        } else {     
-            ((a - b)*(a - b)).sum().to_f64().unwrap().sqrt()            
-        }
+    let mut sum = 0f64;
+    for i in 0..x.len() {
+        sum += (x[i] - y[i]).powf(2.);
     }
 
-
+    return sum;
 }
 
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-    use ndarray::{Array1, ArrayView1, arr1};    
+    use super::*;    
 
     #[test]
     fn measure_simple_euclidian_distance() {
-        let a = arr1(&[1, 2, 3]);
-        let b = arr1(&[4, 5, 6]);             
+        let a = vec![1., 2., 3.];
+        let b = vec![4., 5., 6.];             
         
-        let d_arr = Array1::distance(&a, &b);
-        let d_view = ArrayView1::distance(&a.view(), &b.view());
+        let d_arr = distance(&a, &b);        
 
-        assert!((d_arr - 5.19615242).abs() < 1e-8);
-        assert!((d_view - 5.19615242).abs() < 1e-8);
+        assert!((d_arr - 5.19615242).abs() < 1e-8);        
     }    
 
-    #[test]
-    fn measure_simple_euclidian_distance_static() {
-        let a = arr1(&[-2.1968219, -0.9559913, -0.0431738,  1.0567679,  0.3853515]);
-        let b = arr1(&[-1.7781325, -0.6659839,  0.9526148, -0.9460919, -0.3925300]);    
-
-        let d = Array1::distance(&a, &b);
-
-        assert!((d - 2.422302).abs() < 1e-6);
-    }
 }

src/math/distance/mod.rs

@@ -1,9 +1 @@
-pub mod euclidian;
-
-pub trait Distance<T> {
-
-    fn distance_to(&self, other: &Self) -> f64;
-
-    fn distance(a: &Self, b: &T) -> f64;     
-
-}
+pub mod euclidian;