Port usage of uninitialized to build_uninit

build_uninit is necessary for abstracting over any kind of owned array.

The version of take_slice_upper is still inefficient in one way
(overwriting after copying), but could likely still be an improvement
upon the previous version.

Author: bluss

ndarray-linalg/Cargo.toml

@@ -36,7 +36,7 @@ rand = "0.8.3"
 thiserror = "1.0.24"
 
 [dependencies.ndarray]
-version = "0.15.1"
+version = "0.15.2"
 features = ["blas", "approx", "std"]
 default-features = false
 

ndarray-linalg/src/convert.rs

@@ -46,31 +46,19 @@ where
     }
 }
 
-fn uninitialized<A, S>(l: MatrixLayout) -> ArrayBase<S, Ix2>
-where
-    A: Copy,
-    S: DataOwned<Elem = A>,
-{
-    match l {
-        MatrixLayout::C { row, lda } => unsafe {
-            ArrayBase::uninitialized((row as usize, lda as usize))
-        },
-        MatrixLayout::F { col, lda } => unsafe {
-            ArrayBase::uninitialized((lda as usize, col as usize).f())
-        },
-    }
-}
-
 pub fn replicate<A, Sv, So, D>(a: &ArrayBase<Sv, D>) -> ArrayBase<So, D>
 where
     A: Copy,
     Sv: Data<Elem = A>,
     So: DataOwned<Elem = A> + DataMut,
     D: Dimension,
 {
-    let mut b = unsafe { ArrayBase::uninitialized(a.dim()) };
-    b.assign(a);
-    b
+    unsafe {
+        let ret = ArrayBase::<So, D>::build_uninit(a.dim(), |view| {
+            a.assign_to(view);
+        });
+        ret.assume_init()
+    }
 }
 
 fn clone_with_layout<A, Si, So>(l: MatrixLayout, a: &ArrayBase<Si, Ix2>) -> ArrayBase<So, Ix2>
@@ -79,9 +67,16 @@ where
     Si: Data<Elem = A>,
     So: DataOwned<Elem = A> + DataMut,
 {
-    let mut b = uninitialized(l);
-    b.assign(a);
-    b
+    let shape_builder = match l {
+        MatrixLayout::C { row, lda } => (row as usize, lda as usize).set_f(false),
+        MatrixLayout::F { col, lda } => (lda as usize, col as usize).set_f(true),
+    };
+    unsafe {
+        let ret = ArrayBase::<So, _>::build_uninit(shape_builder, |view| {
+            a.assign_to(view);
+        });
+        ret.assume_init()
+    }
 }
 
 pub fn transpose_data<A, S>(a: &mut ArrayBase<S, Ix2>) -> Result<&mut ArrayBase<S, Ix2>>

ndarray-linalg/src/qr.rs

@@ -135,9 +135,7 @@ where
     S2: DataMut<Elem = A> + DataOwned,
 {
     let av = a.slice(s![..n as isize, ..m as isize]);
-    let mut a = unsafe { ArrayBase::uninitialized((n, m)) };
-    a.assign(&av);
-    a
+    replicate(&av)
 }
 
 fn take_slice_upper<A, S1, S2>(a: &ArrayBase<S1, Ix2>, n: usize, m: usize) -> ArrayBase<S2, Ix2>
@@ -146,10 +144,12 @@ where
     S1: Data<Elem = A>,
     S2: DataMut<Elem = A> + DataOwned,
 {
-    let av = a.slice(s![..n as isize, ..m as isize]);
-    let mut a = unsafe { ArrayBase::uninitialized((n, m)) };
-    for ((i, j), val) in a.indexed_iter_mut() {
-        *val = if i <= j { av[(i, j)] } else { A::zero() };
-    }
+    let av = a.slice(s![..n, ..m]);
+    let mut a = replicate(&av);
+    Zip::indexed(&mut a).for_each(|(i, j), elt| {
+        if i > j {
+            *elt = A::zero()
+        }
+    });
     a
 }