使用BOOST.python从C ++将结构返回到Python [英] Return a structure to Python from C++ using BOOST.python
问题描述
我写了一个C ++方法,从中我需要返回一个结构到Python。
我已经能够使用BOOST按照 mat 从Python发送到C ++。 com / questions / 19136944 / call-c-opencv-functions-from-python-send-a-cv-mat-to-c-dll-which-is-usi> link 。
现在我需要走另一条路;从C ++返回到Python,然后在Python中访问该结构。可以吗?
任何样品或参考链接都是好的。
您可以使用另一个函数from modules / python / src2 / cv2.cpp:
PyObject * pyopencv_from(const cv :: Mat& m)
$ {
if(!m.data)
Py_RETURN_NONE;
cv :: Mat temp,* p =(cv :: Mat *)& m;
if(!p-> refcount || p-> allocator!=& g_numpyAllocator)
{
temp.allocator =& g_numpyAllocator;
m.copyTo(temp);
p =& temp;
}
p-> addref();
return pyObjectFromRefcount(p-> refcount);
}
然后Boost Python包装器将如下所示:
boost :: python :: object toPython(const cv :: Mat& frame)
{
PyObject * pyObjFrame = pyopencv_from帧);
boost :: python :: object boostPyObjFrame(boost :: python :: handle<>((PyObject *)pyObjFrame));
return boostPyObjFrame;
}
请看这个链接: https://wiki.python.org/moin/boost.python/handle ,以确保您使用适当的boost :: python :: handle<>函数。
如果你需要不需要返回一个cv :: Mat但是你可以考虑不同的数据使用boost :: python :: list或boost :: python :: dict。例如,如果你想返回一个2D点的向量到Python,你可以这样做:
boost :: python :: dict toPython(std :: vector< cv :: Point> newPoints,std :: vector< cv :: Point> oldPoints)
{
boost :: python :: dict pointsDict;
boost :: python :: list oldPointsList;
boost :: python :: list newPointsList;
for(size_t ii = 0; ii< oldPoints.size(); ++ ii)
{
oldPointsList.append(boost :: python :: make_tuple [ii] .x,oldPoints [ii] .y));
}
for(size_t ii = 0; ii< newPoints.size(); ++ ii)
{
newPointsList.append(boost :: python :: make_tuple(newPoints [ii] .x,newPoints [ii] .y));
}
pointsDict [oldPoints] = oldPointsList;
pointsDict [newPoints] = newPointsList;
return pointsDict
}
最后Boost Python包装器:
BOOST_PYTHON_MODULE(myWrapper)
{
//只有在返回array(cv :: Mat)时才需要
import_array();
boost :: python :: converter :: registry :: insert(& extract_pyarray,type_id< PyArrayObject>());
def toPython(toPython,& toPython);
}
我没有测试这个特定的解决方案,但它应该原则上工作。 / p>
I have written a C++ method from which I need to return a structure to Python.
I'm already able to send an OpenCV mat
from Python to C++ using BOOST following the method described in this link.
Now I need to go the other way; return from C++ to Python, and then access that structure in Python. Can it be done?
Any samples or reference links would be good. I have tried googling before posting this question and I couldn't get any samples or explanation links.
You can use another function from modules/python/src2/cv2.cpp:
PyObject* pyopencv_from(const cv::Mat& m)
{
if( !m.data )
Py_RETURN_NONE;
cv::Mat temp, *p = (cv::Mat*)&m;
if(!p->refcount || p->allocator != &g_numpyAllocator)
{
temp.allocator = &g_numpyAllocator;
m.copyTo(temp);
p = &temp;
}
p->addref();
return pyObjectFromRefcount(p->refcount);
}
Then the Boost Python wrapper will look like:
boost::python::object toPython( const cv::Mat &frame )
{
PyObject* pyObjFrame = pyopencv_from( frame );
boost::python::object boostPyObjFrame(boost::python::handle<>((PyObject*)pyObjFrame));
return boostPyObjFrame;
}
Please have a look at this link: https://wiki.python.org/moin/boost.python/handle to make sure that you use the appropriate boost::python::handle<> function for your case.
If you need don't need to return a cv::Mat but different data you might consider to use boost::python::list or boost::python::dict. For example if you want to return a vectors of 2D points to Python you can do something like:
boost::python::dict toPython( std::vector<cv::Point> newPoints, std::vector<cv::Point> oldPoints )
{
boost::python::dict pointsDict;
boost::python::list oldPointsList;
boost::python::list newPointsList;
for( size_t ii = 0; ii < oldPoints.size( ); ++ii )
{
oldPointsList.append( boost::python::make_tuple( oldPoints[ii].x, oldPoints[ii].y ) );
}
for( size_t ii = 0; ii < newPoints.size( ); ++ii )
{
newPointsList.append( boost::python::make_tuple( newPoints[ii].x, newPoints[ii].y ) );
}
pointsDict["oldPoints"] = oldPointsList;
pointsDict["newPoints"] = newPointsList;
return pointsDict
}
Finally the Boost Python wrapper:
BOOST_PYTHON_MODULE( myWrapper )
{
// necessary only if array (cv::Mat) is returned
import_array();
boost::python::converter::registry::insert( &extract_pyarray, type_id<PyArrayObject>());
def toPython("toPython", &toPython);
}
I haven't tested this specific solution but it should work in principle.
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