deviation: Implement l_inf_dist

Author: munckymagik

src/deviation.rs

@@ -28,6 +28,10 @@ where
     fn l1_dist(&self, other: &ArrayBase<S, D>) -> A
     where
         A: AddAssign + Clone + Signed;
+
+    fn l_inf_dist(&self, other: &ArrayBase<S, D>) -> A
+    where
+        A: Clone + PartialOrd + Signed;
 }
 
 impl<A, S, D> DeviationExt<A, S, D> for ArrayBase<S, D>
@@ -92,6 +96,23 @@ where
 
         r
     }
+
+    fn l_inf_dist(&self, other: &ArrayBase<S, D>) -> A
+    where
+        A: Clone + PartialOrd + Signed,
+    {
+        let mut max = A::zero();
+
+        Zip::from(self).and(other).apply(|self_i, other_i| {
+            let (a, b) = (self_i.clone(), other_i.clone());
+            let diff = (a - b).abs();
+            if diff > max {
+                max = diff;
+            }
+        });
+
+        max
+    }
 }
 
 #[cfg(test)]
@@ -168,4 +189,20 @@ mod tests {
         assert_eq!(a.l1_dist(&b), (&a - &b).mapv(f64::abs).sum());
         assert_eq!(c.l1_dist(&d), (&c - &d).mapv(i32::abs).sum());
     }
+
+    #[test]
+    fn test_l_inf_dist() {
+        let a = array![1., 1., 1.];
+        let b = array![2., 1., 1.];
+        let c = array![2., 3., 1.];
+        let d = array![2., 3., 4.];
+
+        assert_eq!(a.l_inf_dist(&a), 0.);
+        assert_eq!(a.l_inf_dist(&b), 1.);
+        assert_eq!(b.l_inf_dist(&a), 1.);
+        assert_eq!(a.l_inf_dist(&c), 2.);
+        assert_eq!(c.l_inf_dist(&a), 2.);
+        assert_eq!(a.l_inf_dist(&d), 3.);
+        assert_eq!(d.l_inf_dist(&a), 3.);
+    }
 }