Am Dienstag, 22. Oktober 2019, 23:43:26 CET schrieben Sie:

Am 22.10.19 um 18:16 schrieb Gerion Entrup:

...

Hi,

when using graph-tool from C++, you can use one or more PropertyMaps. In the documentation they are always given as an extra argument. Since graph-tool has internal PropertyMaps, is it possible to extract internal PropertyMaps out of the GraphInterface object?

In pseudo code (like in the documentation): ``` void kcore_bind(GraphInterface& gi) { // Vertex property map of type int32_t typedef typename vprop_map_t<int32_t>::type vprop_t; vprop_t c = boost::any_cast<vprop_t>(gi.get_internal_vertex_property_map("foo"));

gt_dispatch<>() ([&](auto& g){ kcore_decomposition(g, c.get_unchecked()); }, all_graph_views()) (gi.get_graph_view()); } ```

Is there a way to simulate the `get_internal_vertex_property_map` method?

No, that's not possible, because the internal property maps are not stored in GraphInterface; they are kept only in the Python side of things.

But you map pass the property map dictionary (e.g. g.edge_properties) to C++, and lookup from there.

Ok, thank you. I now do exactly that. Here is a minimal example in case anyone else need it (I have not tested exactly this version, maybe some errors are present). Maybe you also know a more elegant version. ``` #include <graph_tool.hh> #include <Python.h> #include <boost/python.hpp> #include <cassert> #include <exception> template <class Property> Property get_property(PyObject* prop_dict, const char* key) { PyObject* prop = PyObject_GetItem(prop_dict, PyUnicode_FromString(key)); assert(prop != nullptr); PyObject* prop_any = PyObject_CallMethod(prop, "_get_any", nullptr); assert(prop_any != nullptr); boost::python::extract<boost::any> get_property(prop_any); assert(get_property.check()); try { return boost::any_cast<Property>(get_property()); } catch (boost::bad_any_cast& e) { std::cerr << "Bad any cast for attribute '" << key << "'" << std::endl; throw e; } } struct CPPGraph { graph_tool::GraphInterface* graph; typename graph_tool::vprop_map_t<std::string>::type strprop; typename graph_tool::vprop_map_t<int>::type intprop; typename graph_tool::vprop_map_t<unsigned char>::type boolprop; typename graph_tool::eprop_map_t<int>::type edge_intprop; typename graph_tool::eprop_map_t<unsigned char>::type edge_boolprop; CPPGraph(PyObject* graph) { PyObject* py_graph = PyObject_GetAttrString(graph, "_Graph__graph"); assert(py_graph != nullptr); boost::python::extract<graph_tool::GraphInterface&> get_graph_interface(py_graph); assert(get_graph_interface.check()); this->graph = &get_graph_interface(); PyObject* vprops = PyObject_GetAttrString(graph, "vertex_properties"); assert(vprops != nullptr); strprop = get_property<decltype(strprop)>(vprops, "strprop"); intprop = get_property<decltype(intprop)>(vprops, "intprop"); boolprop = get_property<decltype(boolprop)>(vprops, "boolprop"); PyObject* eprops = PyObject_GetAttrString(graph, "edge_properties"); assert(eprops != nullptr); edge_intprop = get_property<decltype(edge_intprop)>(eprops, "edge_intprop"); edge_boolprop = get_property<decltype(edge_boolprop)>(eprops, "bool_intprop"); } }; ```