[英]Parameter passing from Python script to C++ with boost-python
我目前正在使用boost-python和boost-numpy将Python嵌入C ++中。 我有以下Python测试脚本:
import numpy as np
import time
def test_qr(m,n):
print("create numpy array")
A = np.random.rand(m, n)
print("Matrix A is {}".format(A))
print("Lets QR factorize this thing! Mathematics is great !!")
ts = time.time()
Q, R = np.linalg.qr(A)
te = time.time()
print("It took {} seconds to factorize A".format(te - ts))
print("The Q matrix is {}".format(Q))
print("The R matrix is {}".format(R))
return Q,R
def sum(m,n):
return m+n
我可以像这样在C ++中执行部分代码:
namespace p = boost::python;
namespace np = boost::python::numpy;
int main() {
Py_Initialize(); //initialize python environment
np::initialize(); //initialize numpy environment
p::object main_module = p::import("__main__");
p::object main_namespace = main_module.attr("__dict__");
// execute code in the main_namespace
p::exec_file("/Users/Michael/CLionProjects/CythonTest/test_file.py",main_namespace); //loads python script
p::exec("m = 100\n"
"n = 100\n"
"Q,R = test_qr(m,n)", main_namespace);
np::ndarray Q_matrix = p::extract<np::ndarray>(main_namespace["Q"]); // extract results as numpy array types
np::ndarray R_matrix = p::extract<np::ndarray>(main_namespace["R"]);
std::cout<<"C++ Q Matrix: \n" << p::extract<char const *>(p::str(Q_matrix)) << std::endl; // extract every element as a
std::cout<<"C++ R Matrix: \n" << p::extract<char const *>(p::str(R_matrix)) << std::endl;
std::cout<<"code also works with numpy, ask for a raise" << std::endl;
p::object sum = main_namespace.attr("sum")(10,10);
int result = p::extract<int>(main_namespace.attr("sum")(10,10));
std::cout<<"sum result works " << result << std::endl;
return 0;}
现在,我尝试在Python脚本中使用sum函数,但我并不总是想编写类似以下的字符串:
p::exec("m = 100\n"
"n = 100\n"
"Q,R = test_qr(m,n)", main_namespace);}
不使用exec函数怎么办?
我已经尝试过类似的事情:
p::object sum = main_namespace.attr("sum")(10,10);
int result = p::extract<int>(main_namespace.attr("sum")(10,10));
std::cout<<"sum result works " << result << std::endl;
如升压文档中所述。 我也尝试使用call_method函数,但是没有用。 我得到了boost :: python :: error_already_set异常,这意味着Python中有问题,但是我不知道是什么。 或退出代码11。
object main_module = import("__main__");
object main_namespace = main_module.attr("__dict__");
object ignored = exec("result = 5 ** 2", main_namespace);
int five_squared = extract<int>(main_namespace["result"]);
注意他们如何在最后一行中提取result
对象: main_namespace["result"]
main_namespace
对象是Python字典,而不是提取其属性,而是在查找使用特定键存储的值。 因此,用[]
索引是要走的路。
C ++代码:
#define BOOST_ALL_NO_LIB
#include <boost/python.hpp>
#include <boost/python/numpy.hpp>
#include <iostream>
namespace bp = boost::python;
int main()
{
try {
Py_Initialize();
bp::object module = bp::import("__main__");
bp::object globals = module.attr("__dict__");
bp::exec_file("bpcall.py", globals);
bp::object sum_fn = globals["sum"];
int result = bp::extract<int>(sum_fn(1,2));
std::cout << "Result (C++) = " << result << "\n";
} catch (bp::error_already_set) {
PyErr_Print();
}
Py_Finalize();
}
Python脚本:
def sum(m,n):
return m+n
输出:
Result (C++) = 3
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