xreducer

template <class F, class CT, class X>
class xt::xreducer

Reducing function operating over specified axes.

The xreducer class implements an xexpression applying a reducing function to an xexpression over the specified axes.

See
reduce
Template Parameters
  • F: the function type
  • CT: the closure type of the xexpression to reduce
  • X: the list of axes

Inherits from xt::xexpression< xreducer< F, CT, X > >, xt::xexpression_const_iterable< xreducer< F, CT, X > >

Constructor

template <class Func, class AX>
xreducer(Func &&func, CT e, AX &&axes)

Constructs an xreducer expression applying the specified function to the given expression over the given axes.

Parameters
  • func: the function to apply
  • e: the expression to reduce
  • axes: the axes along which the reduction is performed

Size and shape

auto size() const

Returns the size of the expression.

auto dimension() const

Returns the number of dimensions of the expression.

auto shape() const

Returns the shape of the expression.

Data

auto operator[](const xindex &index) const

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

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

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

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

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

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

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

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

Broadcasting

template <class S>
bool broadcast_shape(S &shape) const

Broadcast the shape of the reducer to the specified parameter.

Return
a boolean indicating whether the broadcasting is trivial
Parameters
  • shape: the result shape

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

template <class F, class E, class X>
auto xt::reduce(F &&f, E &&e, X &&axes)

Returns an xexpression applying the speficied reducing function to an expresssion over the given axes.

The returned expression either hold a const reference to e or a copy depending on whether e is an lvalue or an rvalue.

Parameters
  • f: the reducing function to apply.
  • e: the xexpression to reduce.
  • axes: the list of axes.