FEAT: Let RandomExt methods apply to array views if possible (sample)

The RandomExt methods for sampling were unintentionally restricted to
owned arrays only (like the original random constructors). Now the
methods which can also apply to array views.

Author: bluss

ndarray-rand/src/lib.rs

@@ -35,7 +35,7 @@ use crate::rand::seq::index;
 use crate::rand::{thread_rng, Rng, SeedableRng};
 
 use ndarray::{Array, Axis, RemoveAxis, ShapeBuilder};
-use ndarray::{ArrayBase, DataOwned, Dimension};
+use ndarray::{ArrayBase, DataOwned, RawData, Data, Dimension};
 #[cfg(feature = "quickcheck")]
 use quickcheck::{Arbitrary, Gen};
 
@@ -63,7 +63,7 @@ pub mod rand_distr {
 /// [`.random_using()`](#tymethod.random_using).
 pub trait RandomExt<S, A, D>
 where
-    S: DataOwned<Elem = A>,
+    S: RawData<Elem = A>,
     D: Dimension,
 {
     /// Create an array with shape `dim` with elements drawn from
@@ -87,6 +87,7 @@ where
     fn random<Sh, IdS>(shape: Sh, distribution: IdS) -> ArrayBase<S, D>
     where
         IdS: Distribution<S::Elem>,
+        S: DataOwned<Elem = A>,
         Sh: ShapeBuilder<Dim = D>;
 
     /// Create an array with shape `dim` with elements drawn from
@@ -117,6 +118,7 @@ where
     where
         IdS: Distribution<S::Elem>,
         R: Rng + ?Sized,
+        S: DataOwned<Elem = A>,
         Sh: ShapeBuilder<Dim = D>;
 
     /// Sample `n_samples` lanes slicing along `axis` using the default RNG.
@@ -163,6 +165,7 @@ where
     fn sample_axis(&self, axis: Axis, n_samples: usize, strategy: SamplingStrategy) -> Array<A, D>
     where
         A: Copy,
+        S: Data<Elem = A>,
         D: RemoveAxis;
 
     /// Sample `n_samples` lanes slicing along `axis` using the specified RNG `rng`.
@@ -223,17 +226,19 @@ where
     where
         R: Rng + ?Sized,
         A: Copy,
+        S: Data<Elem = A>,
         D: RemoveAxis;
 }
 
 impl<S, A, D> RandomExt<S, A, D> for ArrayBase<S, D>
 where
-    S: DataOwned<Elem = A>,
+    S: RawData<Elem = A>,
     D: Dimension,
 {
     fn random<Sh, IdS>(shape: Sh, dist: IdS) -> ArrayBase<S, D>
     where
         IdS: Distribution<S::Elem>,
+        S: DataOwned<Elem = A>,
         Sh: ShapeBuilder<Dim = D>,
     {
         Self::random_using(shape, dist, &mut get_rng())
@@ -243,6 +248,7 @@ where
     where
         IdS: Distribution<S::Elem>,
         R: Rng + ?Sized,
+        S: DataOwned<Elem = A>,
         Sh: ShapeBuilder<Dim = D>,
     {
         Self::from_shape_simple_fn(shape, move || dist.sample(rng))
@@ -251,6 +257,7 @@ where
     fn sample_axis(&self, axis: Axis, n_samples: usize, strategy: SamplingStrategy) -> Array<A, D>
     where
         A: Copy,
+        S: Data<Elem = A>,
         D: RemoveAxis,
     {
         self.sample_axis_using(axis, n_samples, strategy, &mut get_rng())
@@ -266,6 +273,7 @@ where
     where
         R: Rng + ?Sized,
         A: Copy,
+        S: Data<Elem = A>,
         D: RemoveAxis,
     {
         let indices: Vec<_> = match strategy {

ndarray-rand/tests/tests.rs

@@ -35,6 +35,13 @@ fn test_dim_f() {
     }
 }
 
+#[test]
+fn sample_axis_on_view() {
+    let m = 5;
+    let a = Array::random((m, 4), Uniform::new(0., 2.));
+    let _samples = a.view().sample_axis(Axis(0), m, SamplingStrategy::WithoutReplacement);
+}
+
 #[test]
 #[should_panic]
 fn oversampling_without_replacement_should_panic() {