Initial commit

src/math/distance/euclidian.rs

@@ -0,0 +1,48 @@
+use super::Distance;
+use ndarray::{ArrayBase, Data, Dimension};
+use num_traits::Float;
+
+pub struct EuclidianDistance{}
+
+impl<A, S, D> Distance<ArrayBase<S, D>, A> for EuclidianDistance
+where
+    A: Float,        
+    S: Data<Elem = A>,
+    D: Dimension
+{
+
+    fn distance(a: &ArrayBase<S, D>, b: &ArrayBase<S, D>) -> A {
+        if a.len() != b.len() {
+            panic!("vectors a and b have different length");
+        } else {     
+            ((a - b)*(a - b)).sum().sqrt()            
+        }
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ndarray::{arr1, Array};    
+
+    #[test]
+    fn measure_simple_euclidian_distance() {
+        let a = Array::from_vec(vec![1., 2., 3.]);
+        let b = Array::from_vec(vec![4., 5., 6.]);        
+
+        let d = EuclidianDistance::distance(&a, &b);
+
+        assert!((d - 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 = EuclidianDistance::distance(&a, &b);
+
+        assert!((d - 2.422302).abs() < 1e-6);
+    }
+}