ceph/src/boost/libs/python/doc/numpy/reference/unary_ufunc.rst

   1 unary_ufunc
   2 ===========
   3
   4 .. contents :: Table of Contents
   5
   6 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
   7
   8  ``<boost/python/numpy/ufunc.hpp>`` contains the ``unary_ufunc`` structure definitions
   9
  10
  11 synopsis
  12 --------
  13
  14 ::
  15
  16   namespace boost
  17   {
  18   namespace python
  19   {
  20   namespace numpy
  21   {
  22
  23   template <typename TUnaryFunctor,
  24             typename TArgument=typename TUnaryFunctor::argument_type,
  25             typename TResult=typename TUnaryFunctor::result_type>
  26   struct unary_ufunc
  27   {
  28
  29     static object call(TUnaryFunctor & self,
  30                        object const & input,
  31                        object const & output) ;
  32
  33     static object make();
  34
  35   };
  36   }
  37   }
  38   }
  39
  40
  41 constructors
  42 ------------
  43
  44 ::
  45
  46   struct example_unary_ufunc
  47   {
  48     typedef any_valid_type argument_type;
  49     typedef any_valid_type result_type;
  50   };
  51
  52 :Requirements: The ``any_valid`` type must be defined using typedef as a valid C++ type in order to use the struct methods correctly
  53
  54 :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
  55
  56 accessors
  57 ---------
  58
  59 ::
  60
  61   template <typename TUnaryFunctor,
  62             typename TArgument=typename TUnaryFunctor::argument_type,
  63             typename TResult=typename TUnaryFunctor::result_type>
  64   static object call(TUnaryFunctor & self,
  65                      object const & input,
  66                      object const & output);
  67
  68 :Requires: Typenames ``TUnaryFunctor`` and optionally ``TArgument`` for argument type and ``TResult`` for result type
  69
  70 :Effects: Passes a Python object to the underlying C++ functor after broadcasting its arguments
  71
  72 ::
  73
  74   template <typename TUnaryFunctor,
  75             typename TArgument=typename TUnaryFunctor::argument_type,
  76             typename TResult=typename TUnaryFunctor::result_type>
  77   static object make();
  78
  79 :Requires: Typenames ``TUnaryFunctor`` and optionally ``TArgument`` for argument type and ``TResult`` for result type
  80
  81 :Returns: A Python function object to call the overloaded () operator in the struct (in typical usage)
  82
  83
  84
  85 Example(s)
  86 ----------
  87
  88 ::
  89
  90   namespace p = boost::python;
  91   namespace np = boost::python::numpy;
  92
  93   struct UnarySquare
  94   {
  95     typedef double argument_type;
  96     typedef double result_type;
  97     double operator()(double r) const { return r * r;}
  98   };
  99
 100   p::object ud = p::class_<UnarySquare, boost::shared_ptr<UnarySquare> >("UnarySquare").def("__call__", np::unary_ufunc<UnarySquare>::make());
 101   p::object inst = ud();
 102   std::cout << "Square of unary scalar 1.0 is " << p::extract <char const * > (p::str(inst.attr("__call__")(1.0))) << std::endl ;
 103