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request for help re: brandes_betweenness_centrality for weighted graph
by allenem＠pcbi.upenn.edu 29 Sep '09

29 Sep '09

Hi- I've just recently started to use the BGL and was wondering if someone could provide an example (and/or just let me know where I am going wrong) in trying to execute the brandes_betweenness_centrality algorithm for a weighted graph. Below are the relevant code snippets from my program. I am able to compile and run the code, and have successfully iterated over all elements (vertices, edges, and "interaction_weights" to verify that the data are stored correctly) but the calculated betweenness values are the same whether or not I use the edge weight map, which suggests that they are not being considered in the calculation even when passed as a parameter to the brandes_betweenness_centrality function. What am I missing? Thank you, Emily #include <boost/graph/graph_traits.hpp> // iterator functions #include <boost/graph/adjacency_list.hpp> #include <boost/graph/betweenness_centrality.hpp> #include <map> #include <vector> using namespace std; using namespace boost; struct order_edges { template <typename T> bool operator() (const T& x, const T& y) const { return x.get_property() < y.get_property(); } }; /* ============================================================= Main ============================================================ */ int main(int argc, char **argv) { // Define the Graph typedef property < vertex_centrality_t, double > CentralityMap; typedef adjacency_list<vecS, vecS, bidirectionalS, CentralityMap> Graph; typedef graph_traits<Graph>::vertex_descriptor Vertex; typedef graph_traits<Graph>::edge_descriptor Edge; typedef map<Edge, double, order_edges> edge_weight_map_t; edge_weight_map_t base_map; associative_property_map<edge_weight_map_t> interaction_weight(base_map); Graph g; // instance of the graph // determine vertices based upon input from a file // add edges and assign values to associated interaction weights from a file .... brandes_betweenness_centrality(g, get(vertex_centrality,g), interaction_weight); }

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how to concatenate program_options::parsed_options
by Caleb Cushing 29 Sep '09

29 Sep '09

this is a quick summation of the code I'm trying to build // get home directory parsed_options home = parse_environment(desc, "HOME"); // add the relative path to the home directory making it a full path parsed_options rcfile = home + "/.koramarc"; // parse the config file store(parse_config_file(rcfile, desc), vm); honestly all I need to do is parse a config that's in hidden file relative to the users home directory. so if there's a better way that'd work lete me know. -- Caleb Cushing http://xenoterracide.blogspot.com

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[statechart] Passing parameters to state objects
by Robert Dailey 29 Sep '09

29 Sep '09

Hello, I was thinking of using Boost.Statechart as a state machine to manage widget states in my wxWidgets application. Depending on what menu options the user picks in my program, certain buttons on the main window will be enabled or disabled. I figured this would be a good opportunity to use Boost's state machine system. I would create states that would enable or disable certain buttons depending on what events I publish. For example, when the user chooses the "Edit Name" menu item, then buttons for editing a name would be enabled. This means I'd publish a EditNameEnabled event, or something, and then the EditNameMode state would become active, and its constructor would enable certain buttons. Of course, this means I'll need to be able to pass construction parameters to certain fsm state objects, and in the Statechart tutorial they only use default constructors. I'm not sure how I'd pass button object pointers to these state classes so they can work with them. I have two questions: First, does Boost.Statechart seem like the right tool for this job? If yes, then how can I pass parameters to state object constructors? Would I pass the parameters to the Event's constructor, and then somehow access that event instance from the state's constructor? Thanks in advance. --------- Robert Dailey

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serialization of an dynamic array to read/write a image in xml
by Markus Bader 29 Sep '09

29 Sep '09

Hello I like to store and load images from a xml file. My problem is now the dynamic array which keeps the image data. I do not want to copy it into a container and I do not want to go in a for loop over every pixel. Any suggestions? Thanks Max #include <fstream> #include <boost/archive/xml_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/serialization/nvp.hpp> class Image { public: Image() : mWidth(0) , mHeight(0) , mpData(NULL) { } Image(int width, int height, char *pData) : mWidth(width) , mHeight(height) , mpData(pData) { } ~Image() { } template<class archive> void serialize(archive& ar, const unsigned int version) { int i; using boost::serialization::make_nvp; ar & make_nvp("width", mWidth); ar & make_nvp("height", mHeight); // ar & make_nvp("data", mpData, mWidth*mHeight); I know this can not work but --> is there something like this //** How can I serialize the serialization array without making a copy to a container **// } void save(const std::string& rFileName) { std::ofstream ofs(rFileName.c_str()); assert(ofs.good()); boost::archive::xml_oarchive xml(ofs); xml << boost::serialization::make_nvp("Image", this); } void load(const std::string& rFileName) { std::ifstream ifs(rFileName.c_str()); assert(ifs.good()); boost::archive::xml_iarchive xml(ifs); xml >> boost::serialization::make_nvp("Image", *this); } private: int mWidth; int mHeight; char *mpData; }; int main ( int argc, char** argv ) { int h = 640; int w = 480; char *p = new char[w*h]; Image img(w,h,p); img.save("/tmp/img.xml"); img.load("/tmp/img.xml"); delete p; return 0; }

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Use of ccache with Boost
by Dalton, Tom 29 Sep '09

29 Sep '09

Hi, I'm using Boost on Linux however for various reasons I need to rebuild parts of it occasionally. For other C/C++-based tools that are built with autoconf/automake, I've started to use ccache (http://ccache.samba.org/) to speed up recompilation. This is done simply by setting the CC / CXX environment variables to "ccache gcc" / "ccache g++" respectively. I have had a look through the Jam documentation but I can't see an easy way to achieve the same thing when building the Boost distribution. The closest I came was a bit on the trac that simply said I can add a new toolset, but had no real instructions as to how. Thanks for any help! Tom Dalton

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[Proto] grammar matching terminal or pointer to terminal
by joel 29 Sep '09

29 Sep '09

I need to have a proto grammar that matches char, float or any pointer to either char or float. I tried : struct cfptr : or_< terminal<char> , terminal<short> , and_< cfptr , if_< is_pointer< remove_pointer< bp::value_>() >() > > {}; but it faisl to compile when i do : cout << matches< typename terminal<short>::type, cfptr>::value ; by telling me short is not a class or union. should I cut this in two parts or is there a way to do this in one shot? -- ___________________________________________ Joel Falcou - Assistant Professor PARALL Team - LRI - Universite Paris Sud XI Tel : (+33)1 69 15 66 35

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[LockFree] compile problems under VS 2008 sp1
by Roman Shmelev 29 Sep '09

29 Sep '09

Hi! I've written quite simple app to test lockfree::atomic_int. What I see: struct atomic_cas64 { ... #elif defined(_M_IX86) return InterlockedCompareExchange(reinterpret_cast<volatile LONG*>(addr), reinterpret_cast<LONG>(nw), // reinterpret_cast: cannot cast boost::int64_t to LONG reinterpret_cast<LONG>(old)) == old; // reinterpret_cast: cannot cast boost::int64_t to LONG I can give you source code of my simple program if you want. More questions: what is the status of LockFree? Are there any alternatives for atomic_int? Thank you!

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How to Read the stored memory map in C++
by manish4gupta 29 Sep '09

29 Sep '09

I am loading the map into memory with one program and retrieving the map values by another program. Process1. #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/containers/map.hpp> #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/containers/string.hpp> #include <iostream> using namespace boost::interprocess; //Typedefs of allocators and containers typedef managed_shared_memory::segment_manager segment_manager_t; typedef allocator<void, segment_manager_t> void_allocator; typedef allocator<int, segment_manager_t> int_allocator; typedef vector<int, int_allocator> int_vector; typedef allocator<int_vector, segment_manager_t> int_vector_allocator; typedef vector<int_vector, int_vector_allocator> int_vector_vector; typedef allocator<char, segment_manager_t> char_allocator; typedef basic_string<char, std::char_traits<char>, char_allocator> char_string; class complex_data { int id_; char_string char_string_; int_vector_vector int_vector_vector_; public: //Since void_allocator is convertible to any other allocator<T>, we can simplify //the initialization taking just one allocator for all inner containers. complex_data(int id, const char *name, const void_allocator &void_alloc) : id_(id), char_string_(name, void_alloc), int_vector_vector_(void_alloc) {} //Other members... }; //Definition of the map holding a string as key and complex_data as mapped type typedef std::pair<const char_string, int> map_value_type; typedef std::pair<char_string, int> movable_to_map_value_type; typedef allocator<map_value_type, segment_manager_t> map_value_type_allocator; typedef map< char_string, int , std::less<char_string>, map_value_type_allocator> complex_map_type; int main () { //Remove shared memory on construction and destruction struct shm_remove { shm_remove() { shared_memory_object::remove("MySharedMemory"); } ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); } } remover; //Create shared memory managed_shared_memory segment(create_only,"MySharedMemory", 65536); //An allocator convertible to any allocator<T, segment_manager_t> type void_allocator alloc_inst (segment.get_segment_manager()); //Construct the shared memory map and fill it complex_map_type *mymap = segment.construct<complex_map_type> //(object name), (first ctor parameter, second ctor parameter) ("MyMap")(std::less<char_string>(), alloc_inst); std::string s = "test"; char_string cs(s.c_str(), alloc_inst); //string y (cs.c_str()); //std::cout << y <<"\n"; // = (char_string)s; for(int i = 0; i < 100; ++i) { mymap->insert(std::pair<char_string, int>(cs , i)); //char_string key_object(alloc_inst); //map_value_type value(key_object, i); // mymap->insert(value); } return 0; } Process2. #include <boost/interprocess/managed_shared_memory.hpp> #include <boost/interprocess/allocators/allocator.hpp> #include <boost/interprocess/containers/map.hpp> #include <boost/interprocess/containers/vector.hpp> #include <boost/interprocess/containers/string.hpp> #include <iostream> #include <boost/interprocess/containers/vector.hpp> #include <algorithm> using namespace boost::interprocess; typedef managed_shared_memory::segment_manager segment_manager_t; typedef allocator<void, segment_manager_t> void_allocator; typedef allocator<int, segment_manager_t> int_allocator; typedef vector<int, int_allocator> int_vector; typedef allocator<int_vector, segment_manager_t> int_vector_allocator; typedef vector<int_vector, int_vector_allocator> int_vector_vector; typedef allocator<char, segment_manager_t> char_allocator; typedef basic_string<char, std::char_traits<char>, char_allocator> char_string; class complex_data { int id_; char_string char_string_; int_vector_vector int_vector_vector_; public: complex_data(int id, const char *name, const void_allocator &void_alloc): id_(id), char_string_(name, void_alloc), int_vector_vector_(void_alloc) {} }; typedef std::pair<const char_string, int> map_value_type; typedef std::pair<char_string, int> movable_to_map_value_type; typedef allocator<map_value_type, segment_manager_t> map_value_type_allocator; typedef map< char_string, int,std::less<char_string>, map_value_type_allocator> complex_map_type; int main () { using namespace boost::interprocess; try { managed_shared_memory segment(open_only ,"MySharedMemory"); typedef map< char_string, int, std::less<char_string>, map_value_type_allocator> complex_map_type; complex_map_type *MyMap = segment.find<complex_map_type>("MyMap").first; for (complex_map_type::iterator it = MyMap->begin(); it != MyMap->end(); it++) { std::cout << it->first << "\n"; } segment.destroy<complex_map_type>("MyMap"); } catch(...) { shared_memory_object::remove("MySharedMemory"); throw; } shared_memory_object::remove("MySharedMemory"); return 0; } But i am getting the following error message terminate called after throwing an instance of 'boost::interprocess::interprocess_exception' what(): No such file or directory Aborted What is the reason for this? Thanks in advance. -- View this message in context: http://www.nabble.com/How-to-Read-the-stored-memory-map-in-C%2B%2B-tp255063… Sent from the Boost - Users mailing list archive at Nabble.com.

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[MultiArray] How to create / handle a collection of multi-array with varying dimensions?
by Oliver Fochler 28 Sep '09

28 Sep '09

Hi, I'm trying to write some dimension independent routine that makes use of Boost.MultiArray containers. The thing is that I would need several such MultiArrays within this routine with the number of MultiArrays depending on the overall number of dimensions. And here is where it becomes complicated (at least for me). Let N be the overall number of dimensions the routine works with. Then I would a collection of N MultiArrays - but not with fixed dimensions but rather with varying (internal) dimension. That is, a collection like this: boost::multi_array<int, N> A boost::multi_array<int, N-1> B boost::multi_array<int, N-2> C ... However, since N may vary when the routine is called I cannot hardcode the array as above. I was thinking of a vector of multi_array or something like that. But then I don't know how to treat the second template parameter in defining the type of the vector (array, ...). Is there a simple and efficient way to do this? Cheers, Oliver

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[boost][shared_ptr] Trying to make a thread safe Copy-on-write class
by Haledor wow 28 Sep '09

28 Sep '09

Hi, Im trying to make a thread safe Copy-on-write class, but i am unsure how. I want a template class that stores a std::set<T> and i want to be able to add/remove elements while using iterators at the same time without conflicts. I would like to avoid making copies of the entire set each time i want to iterate over the elements. I have tried to use shared_ptr.unique() to decide when to create a new copy of the set but i have been unsuccessful since shared_ptr.use_count() stays at the value 1. I am doing something wrong. I have tried to use something like this as my add function: mutable boost::mutex _mutex; typedef std::set<T> Set; typedef boost::shared_ptr<Set> SetPtr; void add(T element) { boost::unique_lock<boost::mutex> lock(_mutex); if (!(_mySet.unique() || _mySet == 0)) { Set* tmp = _mySet.get(); _mySet = SetPtr(new Set(*tmp)); } _mySet->insert(element); } My thought was that each time an iterator accesses the set the count would increase. Could i make it so (should i)? Any other ideas about a thread safe implementation of a set of elements? I hope someone can help me. Thanks.

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