Remove redundant call to abs in sq_l2_dist (#57)

* Add a benchmark for sq_l2_dist in deviation

* Removes a redundant call to abs in sq_l2_dist

Author: munckymagik

Cargo.toml

@@ -39,4 +39,8 @@ harness = false
 
 [[bench]]
 name = "summary_statistics"
-harness = false
+harness = false
+
+[[bench]]
+name = "deviation"
+harness = false

benches/deviation.rs

@@ -0,0 +1,31 @@
+use criterion::{
+    black_box, criterion_group, criterion_main, AxisScale, Criterion, ParameterizedBenchmark,
+    PlotConfiguration,
+};
+use ndarray::prelude::*;
+use ndarray_rand::RandomExt;
+use ndarray_stats::DeviationExt;
+use rand::distributions::Uniform;
+
+fn sq_l2_dist(c: &mut Criterion) {
+    let lens = vec![10, 100, 1000, 10000];
+    let benchmark = ParameterizedBenchmark::new(
+        "sq_l2_dist",
+        |bencher, &len| {
+            let data = Array::random(len, Uniform::new(0.0, 1.0));
+            let data2 = Array::random(len, Uniform::new(0.0, 1.0));
+
+            bencher.iter(|| black_box(data.sq_l2_dist(&data2).unwrap()))
+        },
+        lens,
+    )
+    .plot_config(PlotConfiguration::default().summary_scale(AxisScale::Logarithmic));
+    c.bench("sq_l2_dist", benchmark);
+}
+
+criterion_group! {
+    name = benches;
+    config = Criterion::default();
+    targets = sq_l2_dist
+}
+criterion_main!(benches);

src/deviation.rs

@@ -261,8 +261,8 @@ where
 
         Zip::from(self).and(other).apply(|self_i, other_i| {
             let (a, b) = (self_i.clone(), other_i.clone());
-            let abs_diff = (a - b).abs();
-            result += abs_diff.clone() * abs_diff;
+            let diff = a - b;
+            result += diff.clone() * diff;
         });
 
         Ok(result)