xoptional_assembly_base¶

Defined in xtensor/xoptional_assembly_base.hpp

template<class D> class xoptional_assembly_base : private xt::xiterable<D>¶

Base class for dense multidimensional optional assemblies.

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 xoptional_assembly_base provides the interface.

Size and shape

auto size() const¶: Returns the number of element in the optional assembly.

auto constexpr dimension() const¶: Returns the number of dimensions of the optional assembly.

auto shape() const¶: Returns the shape of the optional assembly.

auto shape(size_type index) const¶: Returns the i-th dimension of the expression.

auto strides() const¶: Returns the strides of the optional assembly.

auto backstrides() const¶: Returns the backstrides of the optional assembly.

Data

template<class ...Args> bool in_bounds(Args... args) const¶

Returns true only if the the specified position is a valid entry in the expression.

Return

bool

Parameters

args: a list of indices specifying the position in the expression.

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

Returns a reference to the element at the specified position in the optional assembly.

Parameters

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

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

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

Parameters

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

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

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

Parameters

args: a list of indices specifying the position in the optional assembly. Indices must be unsigned integers, the number of indices should be equal to the number of dimensions of the optional assembly.

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 optional assembly, after dimension and bounds checking.

Parameters

args: a list of indices specifying the position in the optional assembly. Indices must be unsigned integers, the number of indices should be equal to the number of dimensions of the optional assembly.

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 optional assembly.

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 optional assembly. Indices must be unsigned integers, the number of indices must be equal to the number of dimensions of the optional assembly, 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 optional assembly.

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 optional assembly. Indices must be unsigned integers, the number of indices must be equal to the number of dimensions of the optional assembly, 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 optional assembly.

Parameters

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

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

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

Parameters

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

template<class ...Args> auto periodic(Args... args)¶

Returns a reference to the element at the specified position in the optional assembly, after applying periodicity to the indices (negative and ‘overflowing’ indices are changed).

Parameters

args: a list of indices specifying the position in the optional assembly. Indices must be unsigned integers, the number of indices should be equal to the number of dimensions of the optional assembly.

template<class ...Args> auto periodic(Args... args) const¶

Returns a constant reference to the element at the specified position in the optional assembly, after applying periodicity to the indices (negative and ‘overflowing’ indices are changed).

Parameters

args: a list of indices specifying the position in the optional assembly. Indices must be unsigned integers, the number of indices should be equal to the number of dimensions of the optional assembly.

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

Returns a reference to the element at the specified position in the optional assembly.

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 optional assembly.

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

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

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 optional assembly.

Broadcasting

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

Broadcast the shape of the optional assembly 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 has_linear_assign(const S &strides) const¶

Checks whether the xoptional_assembly_base can be linearly assigned to an expression with the specified strides.

Return: a boolean indicating whether a linear assign is possible

Public Functions

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

Resizes the optional assembly.

Parameters

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

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

Resizes the optional assembly.

Parameters

shape: the new shape
l: the new layout_type

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

Resizes the optional assembly.

Parameters

shape: the new shape
strides: the new strides

layout_type layout() const¶

Return the layout_type of the container.

Return: layout_type of the container

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

Fills the data with the given value.

Parameters

value: the value to fill the data with.

auto value()¶: Return an expression for the values of the optional assembly.

auto value() const¶: Return a constant expression for the values of the optional assembly.

auto has_value()¶: Return an expression for the missing mask of the optional assembly.

auto has_value() const¶: Return a constant expression for the missing mask of the optional assembly.

template<class S> auto &reshape(const S &shape, layout_type layout) &¶

Reshapes the optional assembly.

Parameters

shape: the new shape
layout: the new layout