xstrided_view

Defined in xtensor/xstrided_view.hpp

template <class CT, class S, layout_type L = layout_type::dynamic, class FST = detail::flat_storage_getter<CT, ::xt::layout_type::row_major >>
class xt::xstrided_view

View of an xexpression using strides.

The xstrided_view class implements a view utilizing an initial offset and strides.

See
strided_view, transpose
Template Parameters
  • CT: the closure type of the xexpression type underlying this view
  • L: the layout of the strided view
  • S: the strides type of the strided view
  • FST: the flat storage type used for the strided view

Inherits from xt::xview_semantic< xstrided_view< CT, S, layout_type::dynamic, detail::flat_storage_getter< CT, ::xt::layout_type::row_major > > >, select_iterable_base_t< layout_type::dynamic, std::decay_t< CT >::static_layout, xstrided_view< CT, S, layout_type::dynamic, detail::flat_storage_getter< CT, ::xt::layout_type::row_major > > >, xt::xstrided_view_base< xstrided_view< CT, S, layout_type::dynamic, detail::flat_storage_getter< CT, ::xt::layout_type::row_major > > >, extension::xstrided_view_base_t< CT, S, layout_type::dynamic, detail::flat_storage_getter< CT, ::xt::layout_type::row_major > >

Constructor

template <class CTA, class SA>
xstrided_view(CTA &&e, SA &&shape, strides_type &&strides, std::size_t offset, layout_type layout)

Constructs an xstrided_view.

Parameters
  • e: the underlying xexpression for this view
  • shape: the shape of the view
  • strides: the strides of the view
  • offset: the offset of the first element in the underlying container
  • layout: the layout of the view

Data

template <class T>
void fill(const T &value)

Fills the view with the given value.

Parameters
  • value: the value to fill the view with.

Extended copy semantic

template <class E>
auto operator=(const xexpression<E> &e)

The extended assignment operator.

Public Functions

auto size() const

Returns the size of the expression.

auto dimension() const

Returns the number of dimensions of the expression.

auto shape(size_type index) const

Returns the i-th dimension of the expression.

template <class… Args>
auto at(Args... args) const

Returns a constant reference to the element at the specified position in the expression, after dimension and bounds checking.

Parameters
  • args: a list of indices specifying the position in the expression. Indices must be unsigned integers, the number of indices should be equal to the number of dimensions of the expression.
Exceptions
  • std::out_of_range: if the number of argument is greater than the number of dimensions or if indices are out of bounds.

typedef xt::xstrided_slice_vector

vector of slices used to build a xstrided_view

template <layout_type L = layout_type::dynamic, class E, class S, class X>
auto xt::strided_view(E &&e, S &&shape, X &&stride, std::size_t offset = 0, layout_type layout = L)

Construct a strided view from an xexpression, shape, strides and offset.

Return
the view
Parameters
  • e: xexpression
  • shape: the shape of the view
  • strides: the new strides of the view
  • offset: the offset of the first element in the underlying container
  • layout: the new layout of the expression
Template Parameters
  • L: the static layout type of the view (default: dynamic)
  • E: type of xexpression
  • S: strides type
  • X: strides type

template <class E>
auto xt::strided_view(E &&e, const xstrided_slice_vector &slices)

Function to create a dynamic view from an xexpression and an xstrided_slice_vector. 

xt::xarray<double> a = {{1, 2, 3}, {4, 5, 6}};
xt::xstrided_slice_vector sv({xt::range(0, 1)});
sv.push_back(xt::range(0, 3, 2));
auto v = xt::strided_view(a, sv);
// ==> {{1, 3}}
Return
initialized strided_view according to slices
Parameters
  • e: xexpression
  • slices: the slice vector

You can also achieve the same with the following short-hand syntax:

xt::xarray<double> a = {{1, 2, 3}, {4, 5, 6}};
auto v = xt::strided_view(a, {xt::range(0, 1), xt::range(0, 3, 2)});
// ==> {{1, 3}}

template <layout_type L = ::xt::layout_type::row_major, class E, class S>
auto xt::reshape_view(E &&e, S &&shape, layout_type)

Return a view on a container with a new shape.

Note: if you resize the underlying container, this view becomes invalidated.

Return
view on xexpression with new shape
Parameters
  • e: xexpression to reshape
  • shape: new shape
  • order: traversal order (optional)