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

   1 dtype
   2 =====
   3
   4 .. contents :: Table of Contents
   5
   6 A `dtype`_ is an object describing the type of the elements of an ndarray
   7
   8 .. _dtype: http://docs.scipy.org/doc/numpy/reference/arrays.dtypes.html#data-type-objects-dtype
   9
  10  ``<boost/python/numpy/dtype.hpp>`` contains the method calls necessary to generate a python object equivalent to a numpy.dtype from builtin C++ objects, as well as to create custom dtypes from user defined types
  11
  12
  13 synopsis
  14 --------
  15
  16 ::
  17
  18   namespace boost
  19   {
  20   namespace python
  21   {
  22   namespace numpy
  23   {
  24
  25   class dtype : public object
  26   {
  27     static python::detail::new_reference convert(object::object_cref arg, bool align);
  28   public:
  29
  30     // Convert an arbitrary Python object to a data-type descriptor object.
  31     template <typename T>
  32     explicit dtype(T arg, bool align=false);
  33
  34     // Get the built-in numpy dtype associated with the given scalar template type.
  35     template <typename T> static dtype get_builtin();
  36
  37     // Return the size of the data type in bytes.
  38     int get_itemsize() const;
  39   };
  40
  41   }
  42   }
  43   }
  44
  45 constructors
  46 ------------
  47
  48 ::
  49
  50   template <typename T>
  51   explicit dtype(T arg, bool align=false)
  52
  53 :Requirements: ``T`` must be either :
  54
  55                * a built-in C++ typename convertible to object
  56                * a valid python object or convertible to object
  57
  58 :Effects: Constructs an object from the supplied python object / convertible
  59           to object / builtin C++ data type
  60
  61 :Throws: Nothing
  62
  63 ::
  64
  65   template <typename T> static dtype get_builtin();
  66
  67 :Requirements: The typename supplied, ``T`` must be a builtin C++ type also supported by numpy
  68
  69 :Returns: Numpy dtype corresponding to builtin C++ type
  70
  71 accessors
  72 ---------
  73
  74 ::
  75
  76   int get_itemsize() const;
  77
  78 :Returns: the size of the data type in bytes.
  79
  80
  81 Example(s)
  82 ----------
  83
  84 ::
  85
  86   namespace p = boost::python;
  87   namespace np = boost::python::numpy;
  88
  89   np::dtype dtype = np::dtype::get_builtin<double>();
  90   p::tuple for_custom_dtype = p::make_tuple("ha",dtype);
  91   np::dtype custom_dtype = np::dtype(list_for_dtype);
  92