python/doc/numpy/reference/unary_ufunc.rst
2016-10-10 14:22:57 -04:00

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unary_ufunc
===========
.. contents :: Table of Contents
A ``unary_ufunc`` is a struct used as an intermediate step to broadcast a single argument so that a C++ function can be converted to a ufunc like function
``<boost/python/numpy/ufunc.hpp>`` contains the ``unary_ufunc`` structure definitions
synopsis
--------
::
namespace boost
{
namespace python
{
namespace numpy
{
template <typename TUnaryFunctor,
typename TArgument=typename TUnaryFunctor::argument_type,
typename TResult=typename TUnaryFunctor::result_type>
struct unary_ufunc
{
static object call(TUnaryFunctor & self,
object const & input,
object const & output) ;
static object make();
};
}
}
}
constructors
------------
::
struct example_unary_ufunc
{
typedef any_valid_type argument_type;
typedef any_valid_type result_type;
};
:Requirements: The ``any_valid`` type must be defined using typedef as a valid C++ type in order to use the struct methods correctly
:Note: The struct must be exposed as a Python class, and an instance of the class must be created to use the ``call`` method corresponding to the ``__call__`` attribute of the Python object
accessors
---------
::
template <typename TUnaryFunctor,
typename TArgument=typename TUnaryFunctor::argument_type,
typename TResult=typename TUnaryFunctor::result_type>
static object call(TUnaryFunctor & self,
object const & input,
object const & output);
:Requires: Typenames ``TUnaryFunctor`` and optionally ``TArgument`` for argument type and ``TResult`` for result type
:Effects: Passes a Python object to the underlying C++ functor after broadcasting its arguments
::
template <typename TUnaryFunctor,
typename TArgument=typename TUnaryFunctor::argument_type,
typename TResult=typename TUnaryFunctor::result_type>
static object make();
:Requires: Typenames ``TUnaryFunctor`` and optionally ``TArgument`` for argument type and ``TResult`` for result type
:Returns: A Python function object to call the overloaded () operator in the struct (in typical usage)
Example(s)
----------
::
namespace p = boost::python;
namespace np = boost::python::numpy;
struct UnarySquare
{
typedef double argument_type;
typedef double result_type;
double operator()(double r) const { return r * r;}
};
p::object ud = p::class_<UnarySquare, boost::shared_ptr<UnarySquare> >("UnarySquare").def("__call__", np::unary_ufunc<UnarySquare>::make());
p::object inst = ud();
std::cout << "Square of unary scalar 1.0 is " << p::extract <char const * > (p::str(inst.attr("__call__")(1.0))) << std::endl ;