python/example/numpy/fromdata.cpp
2016-10-23 21:34:16 -04:00

49 lines
1.7 KiB
C++

// Copyright Ankit Daftery 2011-2012.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
/**
* @brief An example to show how to access data using raw pointers. This shows that you can use and
* manipulate data in either Python or C++ and have the changes reflected in both.
*/
#include <boost/python/numpy.hpp>
#include <iostream>
namespace p = boost::python;
namespace np = boost::python::numpy;
int main(int argc, char **argv)
{
// Initialize the Python runtime.
Py_Initialize();
// Initialize NumPy
np::initialize();
// Create an array in C++
int arr[] = {1,2,3,4} ;
// Create the ndarray in Python
np::ndarray py_array = np::from_data(arr, np::dtype::get_builtin<int>() , p::make_tuple(4), p::make_tuple(4), p::object());
// Print the ndarray that we just created, and the source C++ array
std::cout << "C++ array :" << std::endl ;
for (int j=0;j<4;j++)
{
std::cout << arr[j] << ' ' ;
}
std::cout << std::endl << "Python ndarray :" << p::extract<char const *>(p::str(py_array)) << std::endl;
// Change an element in the python ndarray
py_array[1] = 5 ;
// And see if the C++ container is changed or not
std::cout << "Is the change reflected in the C++ array used to create the ndarray ? " << std::endl ;
for (int j = 0;j<4 ; j++)
{
std::cout << arr[j] << ' ' ;
}
// Conversely, change it in C++
arr[2] = 8 ;
// And see if the changes are reflected in the Python ndarray
std::cout << std::endl << "Is the change reflected in the Python ndarray ?" << std::endl << p::extract<char const *>(p::str(py_array)) << std::endl;
}