ceph/src/boost/libs/python/example/numpy/dtype.cpp

   1 // Copyright Ankit Daftery 2011-2012.
   2 // Distributed under the Boost Software License, Version 1.0.
   3 //    (See accompanying file LICENSE_1_0.txt or copy at
   4 //          http://www.boost.org/LICENSE_1_0.txt)
   5
   6 /**
   7  *  @brief An example to show how to create ndarrays with built-in python data types, and extract
   8  *         the types and values of member variables
   9  *
  10  *  @todo Add an example to show type conversion.
  11  *        Add an example to show use of user-defined types
  12  *
  13  */
  14
  15 #include <boost/python/numpy.hpp>
  16 #include <iostream>
  17
  18 namespace p = boost::python;
  19 namespace np = boost::python::numpy;
  20
  21 int main(int argc, char **argv)
  22 {
  23   // Initialize the Python runtime.
  24   Py_Initialize();
  25   // Initialize NumPy
  26   np::initialize();
  27   // Create a 3x3 shape...
  28   p::tuple shape = p::make_tuple(3, 3);
  29   // ...as well as a type for C++ double
  30   np::dtype dtype = np::dtype::get_builtin<double>();
  31   // Construct an array with the above shape and type
  32   np::ndarray a = np::zeros(shape, dtype);
  33   // Print the array
  34   std::cout << "Original array:\n" << p::extract<char const *>(p::str(a)) << std::endl;
  35   // Print the datatype of the elements
  36   std::cout << "Datatype is:\n" << p::extract<char const *>(p::str(a.get_dtype())) << std::endl ;
  37   // Using user defined dtypes to create dtype and an array of the custom dtype
  38   // First create a tuple with a variable name and its dtype, double, to create a custom dtype
  39   p::tuple for_custom_dtype = p::make_tuple("ha",dtype) ;
  40   // The list needs to be created, because the constructor to create the custom dtype
  41   // takes a list of (variable,variable_type) as an argument
  42   p::list list_for_dtype ;
  43   list_for_dtype.append(for_custom_dtype) ;
  44   // Create the custom dtype
  45   np::dtype custom_dtype = np::dtype(list_for_dtype) ;
  46   // Create an ndarray with the custom dtype
  47   np::ndarray new_array = np::zeros(shape,custom_dtype);
  48
  49 }