layout

Defined in xtensor/xlayout.hpp

enum xt::layout_type

layout_type enum for xcontainer based xexpressions

Values:

dynamic = 0x00

dynamic layout_type: you can resize to row major, column major, or use custom strides

any = 0xFF

layout_type compatible with all others

row_major = 0x01

row major layout_type

column_major = 0x02

column major layout_type

template <class... Args>
constexpr layout_type xt::compute_layout(Args... args)

Implementation of the following logical table:

  | d | a | r | c |
--+---+---+---+---+
d | d | d | d | d |
a | d | a | r | c |
r | d | r | r | d |
c | d | c | d | c |
d = dynamic, a = any, r = row_major, c = column_major.
Using bitmasks to avoid nested if-else statements.

Return
the output layout, computed with the previous logical table.
Parameters
  • args: the input layouts.

xcontainer

Defined in xtensor/xcontainer.hpp

template <class D>
class xcontainer : xt::xiterable<D>

Base class for dense multidimensional containers.

Base class for dense multidimensional optional assemblies.

The xcontainer class defines the interface for dense multidimensional container classes. It does not embed any data container, this responsibility is delegated to the inheriting classes.

The

xoptional_assembly_base class defines the interface for dense multidimensional optional assembly classes. Optional assembly classes hold optional values and are optimized for tensor operations. xoptional_assembly_base does not embed any data container, this responsibility is delegated to the inheriting classes.
Template Parameters
  • D: The derived type, i.e. the inheriting class for which xcontainer provides the interface.

Template Parameters

Subclassed by xt::xstrided_container< D >

Size and shape

auto size() const

Returns the number of element in the container.

constexpr auto dimension() const

Returns the number of dimensions of the container.

constexpr auto shape() const

Returns the shape of the container.

constexpr auto strides() const

Returns the strides of the container.

constexpr auto backstrides() const

Returns the backstrides of the container.

Data

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

Fills the container with the given value.

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

auto storage()

Returns a reference to the buffer containing the elements of the container.

auto storage() const

Returns a constant reference to the buffer containing the elements of the container.

auto data()

Returns a pointer to the underlying array serving as element storage.

The pointer is such that range [data(); data() + size()] is always a valid range, even if the container is empty (data() is not is not dereferenceable in that case)

auto data() const

Returns a constant pointer to the underlying array serving as element storage.

The pointer is such that range [data(); data() + size()] is always a valid range, even if the container is empty (data() is not is not dereferenceable in that case)

auto data_offset() const

Returns the offset to the first element in the container.

template <class... Args>
auto operator()(Args... args)

Returns a reference to the element at the specified position in the container.

Parameters
  • args: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices should be equal or greater than the number of dimensions of the container.

template <class... Args>
auto operator()(Args... args) const

Returns a constant reference to the element at the specified position in the container.

Parameters
  • args: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices should be equal or greater than the number of dimensions of the container.

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

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

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

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

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

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

template <class... Args>
auto unchecked(Args... args)

Returns a reference to the element at the specified position in the container.

Warning
This method is meant for performance, for expressions with a dynamic number of dimensions (i.e. not known at compile time). Since it may have undefined behavior (see parameters), operator() should be prefered whenever it is possible.
Warning
This method is NOT compatible with broadcasting, meaning the following code has undefined behavior:
xt::xarray<double> a = {{0, 1}, {2, 3}};
xt::xarray<double> b = {0, 1};
auto fd = a + b;
double res = fd.uncheked(0, 1);
Parameters
  • args: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices must be equal to the number of dimensions of the container, else the behavior is undefined.

template <class... Args>
auto unchecked(Args... args) const

Returns a constant reference to the element at the specified position in the container.

Warning
This method is meant for performance, for expressions with a dynamic number of dimensions (i.e. not known at compile time). Since it may have undefined behavior (see parameters), operator() should be prefered whenever it is possible.
Warning
This method is NOT compatible with broadcasting, meaning the following code has undefined behavior:
xt::xarray<double> a = {{0, 1}, {2, 3}};
xt::xarray<double> b = {0, 1};
auto fd = a + b;
double res = fd.uncheked(0, 1);
Parameters
  • args: a list of indices specifying the position in the container. Indices must be unsigned integers, the number of indices must be equal to the number of dimensions of the container, else the behavior is undefined.

template <class S>
auto operator[](const S &index)

Returns a reference to the element at the specified position in the container.

Parameters
  • index: a sequence of indices specifying the position in the container. Indices must be unsigned integers, the number of indices in the list should be equal or greater than the number of dimensions of the container.

template <class S>
auto operator[](const S &index) const

Returns a constant reference to the element at the specified position in the container.

Parameters
  • index: a sequence of indices specifying the position in the container. Indices must be unsigned integers, the number of indices in the list should be equal or greater than the number of dimensions of the container.

template <class It>
auto element(It first, It last)

Returns a reference to the element at the specified position in the container.

Parameters
  • first: iterator starting the sequence of indices
  • last: iterator ending the sequence of indices The number of indices in the sequence should be equal to or greater than the number of dimensions of the container.

template <class It>
auto element(It first, It last) const

Returns a reference to the element at the specified position in the container.

Parameters
  • first: iterator starting the sequence of indices
  • last: iterator ending the sequence of indices The number of indices in the sequence should be equal to or greater than the number of dimensions of the container.

Broadcasting

template <class S>
bool broadcast_shape(S &shape, bool reuse_cache = false) const

Broadcast the shape of the container to the specified parameter.

Return
a boolean indicating whether the broadcasting is trivial
Parameters
  • shape: the result shape
  • reuse_cache: parameter for internal optimization

template <class S>
bool is_trivial_broadcast(const S &strides) const

Compares the specified strides with those of the container to see whether the broadcasting is trivial.

Return
a boolean indicating whether the broadcasting is trivial

xstrided_container

Defined in xtensor/xcontainer.hpp

template <class D>
class xstrided_container : public xt::xcontainer<D>

Partial implementation of xcontainer that embeds the strides and the shape.

The xstrided_container class is a partial implementation of the xcontainer interface that embed the strides and the shape of the multidimensional container. It does not embed the data container, this responsibility is delegated to the inheriting classes.

Template Parameters
  • D: The derived type, i.e. the inheriting class for which xstrided_container provides the partial imlpementation of xcontainer.

Public Functions

template <class S = shape_type>
void resize(S &&shape, bool force = false)

resizes the container.

Parameters
  • shape: the new shape
  • force: force reshaping, even if the shape stays the same (default: false)

template <class S = shape_type>
void resize(S &&shape, layout_type l)

resizes the container.

Parameters
  • shape: the new shape
  • l: the new layout_type

template <class S = shape_type>
void resize(S &&shape, const strides_type &strides)

Resizes the container.

Parameters
  • shape: the new shape
  • strides: the new strides

template <class S = shape_type>
void reshape(S &&shape, layout_type layout = base_type::static_layout)

Reshapes the container and keeps old elements.

Parameters
  • shape: the new shape (has to have same number of elements as the original container)
  • layout: the layout to compute the strides (defaults to static layout of the container, or for a container with dynamic layout to XTENSOR_DEFAULT_LAYOUT)

layout_type layout() const

Return the layout_type of the container.

Return
layout_type of the container