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 demonstrate use of universal functions or ufuncs
8 *
9 *
10 * @todo Calling the overloaded () operator is in a roundabout manner, find a simpler way
11 * None of the methods like np::add, np::multiply etc are supported as yet
12 */
13
14 #include <boost/python/numpy.hpp>
15 #include <iostream>
16
17 namespace p = boost::python;
18 namespace np = boost::python::numpy;
19
20
21 // Create the structs necessary to implement the ufuncs
22 // The typedefs *must* be made
23
24 struct UnarySquare
25 {
26 typedef double argument_type;
27 typedef double result_type;
28
operator ()UnarySquare29 double operator()(double r) const { return r * r;}
30 };
31
32 struct BinarySquare
33 {
34 typedef double first_argument_type;
35 typedef double second_argument_type;
36 typedef double result_type;
37
operator ()BinarySquare38 double operator()(double a,double b) const { return (a*a + b*b) ; }
39 };
40
main(int argc,char ** argv)41 int main(int argc, char **argv)
42 {
43 // Initialize the Python runtime.
44 Py_Initialize();
45 // Initialize NumPy
46 np::initialize();
47 // Expose the struct UnarySquare to Python as a class, and let ud be the class object
48 p::object ud = p::class_<UnarySquare, boost::shared_ptr<UnarySquare> >("UnarySquare")
49 .def("__call__", np::unary_ufunc<UnarySquare>::make());
50 // Let inst be an instance of the class ud
51 p::object inst = ud();
52 // Use the "__call__" method to call the overloaded () operator and print the value
53 std::cout << "Square of unary scalar 1.0 is " << p::extract <char const * > (p::str(inst.attr("__call__")(1.0))) << std::endl ;
54 // Create an array in C++
55 int arr[] = {1,2,3,4} ;
56 // ..and use it to create the ndarray in Python
57 np::ndarray demo_array = np::from_data(arr, np::dtype::get_builtin<int>() , p::make_tuple(4), p::make_tuple(4), p::object());
58 // Print out the demo array
59 std::cout << "Demo array is " << p::extract <char const * > (p::str(demo_array)) << std::endl ;
60 // Call the "__call__" method to perform the operation and assign the value to result_array
61 p::object result_array = inst.attr("__call__")(demo_array) ;
62 // Print the resultant array
63 std::cout << "Square of demo array is " << p::extract <char const * > (p::str(result_array)) << std::endl ;
64 // Lets try the same with a list
65 p::list li ;
66 li.append(3);
67 li.append(7);
68 // Print out the demo list
69 std::cout << "Demo list is " << p::extract <char const * > (p::str(li)) << std::endl ;
70 // Call the ufunc for the list
71 result_array = inst.attr("__call__")(li) ;
72 // And print the list out
73 std::cout << "Square of demo list is " << p::extract <char const * > (p::str(result_array)) << std::endl ;
74 // Now lets try Binary ufuncs
75 // Expose the struct BinarySquare to Python as a class, and let ud be the class object
76 ud = p::class_<BinarySquare, boost::shared_ptr<BinarySquare> >("BinarySquare")
77 .def("__call__", np::binary_ufunc<BinarySquare>::make());
78 // Again initialise inst as an instance of the class ud
79 inst = ud();
80 // Print the two input listsPrint the two input lists
81 std::cout << "The two input list for binary ufunc are " << std::endl << p::extract <char const * > (p::str(demo_array)) << std::endl << p::extract <char const * > (p::str(demo_array)) << std::endl ;
82 // Call the binary ufunc taking demo_array as both inputs
83 result_array = inst.attr("__call__")(demo_array,demo_array) ;
84 std::cout << "Square of list with binary ufunc is " << p::extract <char const * > (p::str(result_array)) << std::endl ;
85 }
86
87