xbroadcast¶
Defined in xtensor/xbroadcast.hpp
-
template<class CT, class X>
class xbroadcast : public xt::xsharable_expression<xbroadcast<CT, X>>, public xt::xconst_iterable<xbroadcast<CT, X>>, public xt::xconst_accessible<xbroadcast<CT, X>>, public extension::xbroadcast_base_t<CT, X>¶ Broadcasted xexpression to a specified shape.
The xbroadcast class implements the broadcasting of an xexpression to a specified shape. xbroadcast is not meant to be used directly, but only with the broadcast helper functions.
See also
- Template Parameters
CT – the closure type of the xexpression to broadcast
X – the type of the specified shape.
Constructor
-
template<class CTA, class S>
inline xbroadcast(CTA &&e, const S &s)¶ Constructs an xbroadcast expression broadcasting the specified xexpression to the given shape.
- Parameters
e – the expression to broadcast
s – the shape to apply
-
template<class CTA>
inline xbroadcast(CTA &&e, shape_type &&s)¶ Constructs an xbroadcast expression broadcasting the specified xexpression to the given shape.
- Parameters
e – the expression to broadcast
s – the shape to apply
Size and shape
-
inline const inner_shape_type &shape() const noexcept¶
Returns the shape of the expression.
-
inline layout_type layout() const noexcept¶
Returns the layout_type of the expression.
Data
-
inline const xexpression_type &expression() const noexcept¶
Returns a constant reference to the underlying expression of the broadcast expression.
-
template<class ...Args>
inline auto operator()(Args... args) const -> const_reference¶ Returns a constant reference to the element at the specified position in the expression.
- Parameters
args – a list of indices specifying the position in the function. Indices must be unsigned integers, the number of indices should be equal or greater than the number of dimensions of the expression.
-
template<class ...Args>
inline auto unchecked(Args... args) const -> const_reference¶ Returns a constant reference to the element at the specified position in the expression.
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 preferred 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 expression. Indices must be unsigned integers, the number of indices must be equal to the number of dimensions of the expression, else the behavior is undefined.
-
template<class It>
inline auto element(It, It last) const -> const_reference¶ Returns a constant reference to the element at the specified position in the expression.
- 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 function.
Broadcasting
-
template<class S>
inline bool broadcast_shape(S &shape, bool reuse_cache = false) const¶ Broadcast the shape of the function to the specified parameter.
- Parameters
shape – the result shape
reuse_cache – parameter for internal optimization
- Returns
a boolean indicating whether the broadcasting is trivial
-
template<class E, class S>
inline auto xt::broadcast(E &&e, const S &s)¶ Returns an xexpression broadcasting the given expression to a specified shape.
The returned expression either hold a const reference to
e
or a copy depending on whethere
is an lvalue or an rvalue.- Template Parameters
e – the xexpression to broadcast
s – the specified shape to broadcast.