Merge pull request #990 from rust-ndarray/push-append

Rename append_row/column to push_row/column; add method push

Author: bluss

src/impl_owned_array.rs

@@ -99,15 +99,15 @@ impl<A> Array<A, Ix2> {
     ///
     /// // create an empty array and append
     /// let mut a = Array::zeros((0, 4));
-    /// a.append_row(ArrayView::from(&[ 1.,  2.,  3.,  4.])).unwrap();
-    /// a.append_row(ArrayView::from(&[-1., -2., -3., -4.])).unwrap();
+    /// a.push_row(ArrayView::from(&[ 1.,  2.,  3.,  4.])).unwrap();
+    /// a.push_row(ArrayView::from(&[-1., -2., -3., -4.])).unwrap();
     ///
     /// assert_eq!(
     ///     a,
     ///     array![[ 1.,  2.,  3.,  4.],
     ///            [-1., -2., -3., -4.]]);
     /// ```
-    pub fn append_row(&mut self, row: ArrayView<A, Ix1>) -> Result<(), ShapeError>
+    pub fn push_row(&mut self, row: ArrayView<A, Ix1>) -> Result<(), ShapeError>
     where
         A: Clone,
     {
@@ -136,15 +136,15 @@ impl<A> Array<A, Ix2> {
     ///
     /// // create an empty array and append
     /// let mut a = Array::zeros((2, 0));
-    /// a.append_column(ArrayView::from(&[1., 2.])).unwrap();
-    /// a.append_column(ArrayView::from(&[-1., -2.])).unwrap();
+    /// a.push_column(ArrayView::from(&[1., 2.])).unwrap();
+    /// a.push_column(ArrayView::from(&[-1., -2.])).unwrap();
     ///
     /// assert_eq!(
     ///     a,
     ///     array![[1., -1.],
     ///            [2., -2.]]);
     /// ```
-    pub fn append_column(&mut self, column: ArrayView<A, Ix1>) -> Result<(), ShapeError>
+    pub fn push_column(&mut self, column: ArrayView<A, Ix1>) -> Result<(), ShapeError>
     where
         A: Clone,
     {
@@ -278,8 +278,66 @@ impl<A, D> Array<A, D>
         }
     }
 
+    /// Append an array to the array along an axis
+    ///
+    /// Where the item to push to the array has one dimension less than the `self` array. This
+    /// method is equivalent to `self.append(axis, array.insert_axis(axis))`.
+    ///
+    /// The axis-to-append-to `axis` must be the array's "growing axis" for this operation
+    /// to succeed. The growing axis is the outermost or last-visited when elements are visited in
+    /// memory order:
+    ///
+    /// `axis` must be the growing axis of the current array, an axis with length 0 or 1.
+    ///
+    /// - This is the 0th axis for standard layout arrays
+    /// - This is the *n*-1 th axis for fortran layout arrays
+    /// - If the array is empty (the axis or any other has length 0) or if `axis`
+    ///   has length 1, then the array can always be appended.
+    ///
+    /// ***Errors*** with a shape error if the shape of self does not match the array-to-append;
+    /// all axes *except* the axis along which it being appended matter for this check.
+    ///
+    /// The memory layout of the `self` array matters for ensuring that the append is efficient.
+    /// Appending automatically changes memory layout of the array so that it is appended to
+    /// along the "growing axis".
+    ///
+    /// Ensure appending is efficient by for example starting from an empty array and/or always
+    /// appending to an array along the same axis.
+    ///
+    /// The amortized average complexity of the append, when appending along its growing axis, is
+    /// O(*m*) where *m* is the length of the row.
+    ///
+    /// The memory layout of the argument `array` does not matter to the same extent.
+    ///
+    /// ```rust
+    /// use ndarray::{Array, ArrayView, array, Axis};
+    ///
+    /// // create an empty array and push rows to it
+    /// let mut a = Array::zeros((0, 4));
+    /// let ones  = ArrayView::from(&[1.; 4]);
+    /// let zeros = ArrayView::from(&[0.; 4]);
+    /// a.push(Axis(0), ones).unwrap();
+    /// a.push(Axis(0), zeros).unwrap();
+    /// a.push(Axis(0), ones).unwrap();
+    ///
+    /// assert_eq!(
+    ///     a,
+    ///     array![[1., 1., 1., 1.],
+    ///            [0., 0., 0., 0.],
+    ///            [1., 1., 1., 1.]]);
+    /// ```
+    pub fn push(&mut self, axis: Axis, array: ArrayView<A, D::Smaller>)
+        -> Result<(), ShapeError>
+    where
+        A: Clone,
+        D: RemoveAxis,
+    {
+        // same-dimensionality conversion
+        self.append(axis, array.insert_axis(axis).into_dimensionality::<D>().unwrap())
+    }
+
 
-    /// Append an array to the array
+    /// Append an array to the array along an axis
     ///
     /// The axis-to-append-to `axis` must be the array's "growing axis" for this operation
     /// to succeed. The growing axis is the outermost or last-visited when elements are visited in
@@ -338,18 +396,19 @@ impl<A, D> Array<A, D>
         }
 
         let current_axis_len = self.len_of(axis);
-        let remaining_shape = self.raw_dim().remove_axis(axis);
-        let array_rem_shape = array.raw_dim().remove_axis(axis);
+        let self_dim = self.raw_dim();
+        let array_dim = array.raw_dim();
+        let remaining_shape = self_dim.remove_axis(axis);
+        let array_rem_shape = array_dim.remove_axis(axis);
 
         if remaining_shape != array_rem_shape {
             return Err(ShapeError::from_kind(ErrorKind::IncompatibleShape));
         }
 
         let len_to_append = array.len();
 
-        let array_shape = array.raw_dim();
-        let mut res_dim = self.raw_dim();
-        res_dim[axis.index()] += array_shape[axis.index()];
+        let mut res_dim = self_dim;
+        res_dim[axis.index()] += array_dim[axis.index()];
         let new_len = dimension::size_of_shape_checked(&res_dim)?;
 
         if len_to_append == 0 {
@@ -468,7 +527,7 @@ impl<A, D> Array<A, D>
 
             // With > 0 strides, the current end of data is the correct base pointer for tail_view
             let tail_ptr = self.data.as_end_nonnull();
-            let mut tail_view = RawArrayViewMut::new(tail_ptr, array_shape, tail_strides);
+            let mut tail_view = RawArrayViewMut::new(tail_ptr, array_dim, tail_strides);
 
             if tail_view.ndim() > 1 {
                 sort_axes_in_default_order_tandem(&mut tail_view, &mut array);