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[Boost.Graph] How to build a directed graph
by Lucas Soltic 10 Jan '14

10 Jan '14

Hello, I’m trying to build a DAG thanks to BGL, the source code builds fine but crashes at runtime. And I’m a bit lost on the reason. I don’t even know if my typedefs are correct according to my purpose: simply building a DAG whose nodes are « Classes » with arcs that point to « parents ». I’ve written the following: #include <list> #include <boost/graph/directed_graph.hpp> class MyClass {}; typedef MyClass* Vertex; typedef std::pair<Vertex, Vertex> Edge; typedef boost::directed_graph<Vertex, Edge> ClassInheritanceGraph; static ClassInheritanceGraph g_parentClassGraph; void buildGraph(void) { std::list<Edge> edges; edges.push_back(std::make_pair(new MyClass, new MyClass)); edges.push_back(std::make_pair(new MyClass, new MyClass)); std::list<Edge>::iterator edgesIt; for (edgesIt = edges.begin(); edgesIt != edges.end(); edgesIt++) { Vertex child = edgesIt->first; Vertex parent = edgesIt->second; boost::add_edge(child, parent, g_parentClassGraph); } } int main() { buildGraph(); return 0; } The program crashes on boost::add_edge() with a segfault. The point is I don’t know if I’m correctly using BGL. I don’t really know what is the proper way (I don’t understand everything from the BGL documentation…). I tried to debug the program but with all those template arguments I don’t understand the error (http://pastebin.com/BRgz3uL7 in case you want to make nightmares :) ). Thus in case someone understands what’s wrong here I would be really grateful for some help! Thanks, Lucas

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[iterator] error while accessing member of result of brackets-operator
by Sebastian Pfützner 10 Jan '14

10 Jan '14

Hello, the following code does not compile with the last line in main(). The error message is main.cpp: In function 'int main()': main.cpp:37:8: error: 'boost::detail::operator_brackets_result<It, S, S&>::type' has no member named 'i' it[3].i = 0; ^ What could be the problem? #include <boost/iterator/iterator_facade.hpp> struct S { int i; float f; }; class It : public boost::iterator_facade<It, S, boost::random_access_traversal_tag> { private: friend class boost::iterator_core_access; static S s; reference dereference() const { return s; } bool equal(It const&) const { return true; } void increment() {} void decrement() {} void advance(difference_type n) {} difference_type distance_to(It const&) const { return 0; } }; int main() { It it; (*(it + 3)).i = 0; S& s = it[3]; s.i = 0; it[3].i = 0; } -- Sebastian Pfützner s.pfuetzner(a)onlinehome.de ICQ-ID: 39965036

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boost process : how to use it
by Vincent R. 09 Jan '14

09 Jan '14

Hi, What is the status of boost:process, when looking on internet you can find different version that are more or less compatible. Not an ideal situation and I am a bit surprised that this lib doesn't get more love from c++ dev. Anyway after a long time coding in easier language I decided to do a small project under linux that consists in a tcp server running on linux that start some process initiated by a client and sends the output. So I have downaloaded the most "official" version I could find here http://www.highscore.de/boost/process/ and I tried the following code : #include <cassert> #include <iostream> #include <map> #include <string> #include <sstream> #include <vector> #include <boost/asio.hpp> #include <boost/enable_shared_from_this.hpp> #include <boost/process.hpp> namespace asio = boost::asio; namespace bp = boost::process; using asio::ip::tcp; bp::child start_child() { std::string exec = boost::process::find_executable_in_path("dpkg"); std::vector<std::string> args; args.push_back("-l"); bp::context ctx; ctx.stderr_behavior = bp::capture_stream(); return bp::launch(exec, args, ctx); } int main(int argc, char *argv[]) { std::string value; bp::child c = start_child(); bp::pistream &is = c.get_stderr(); std::string line; while (std::getline(is, line)) { value += line + "\r\n"; } c.wait(); std::cout << "OUTPUT: " << value << std::endl; return 0; } My first question is how can I merge the stderr with stdout because some commands use stdout and some others stderr ? My second question is : why the code above doesn't work properly and doesn't handle the arguments I am passing ? Indeed when I run the code I get the following output : OUTPUT: dpkg: error: need an action option it means that the -l is not taken in consideration. Thanks for any help

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Re: [Boost-users] How to create distributed_property_map (??????? ?????)
by Николай Кинаш 09 Jan '14

09 Jan '14

So, now i have: struct centrality_t { typedef vertex_property_tag kind; }; typedef property<centrality_t, double> VertexCentrality; typedef boost::adjacency_list<listS, distributedS<mpi_process_group,vecS>, undirectedS, VertexCentrality> Graph; typedef boost::unique_rmat_iterator<boost::minstd_rand, Graph> RMATGen; struct no_self_loops { no_self_loops() {} bool operator()(const std::pair<int,int>& e) { return e.first != e.second; } }; template <typename G> struct VertexKey { typedef int value_type; typedef typename graph_traits<G>::vertex_descriptor key_type; typedef read_write_property_map_tag category; typedef int* reference; }; int main(int argc, char* argv[]) { boost::mpi::environment env(argc, argv); boost::minstd_rand gen; unsigned int SCALE = atoi(argv[1]); unsigned int EDGE_FACTOR = atoi(argv[2]); unsigned int N = pow(2, SCALE); unsigned int E = EDGE_FACTOR * N; Graph g( boost::make_filter_iterator<no_self_loops> ( RMATGen(gen, N, E, 0.45, 0.15, 0.15, 0.25), RMATGen()), boost::make_filter_iterator<no_self_loops>(RMATGen(), RMATGen()), N); typedef boost::property_map<Graph, centrality_t>::type LocalMap; typedef boost::parallel::distributed_property_map<mpi_process_group, LocalMap, VertexKey<Graph> > CentralityMap; LocalMap local_map = get(centrality_t(), g); mpi_process_group process_groupe; //VertexKey<Graph> vertex_key; CentralityMap centrality_map(process_groupe, local_map); //brandes_betweenness_centrality(g, centrality_map); } network.cpp: In function ‘int main(int, char**)’: network.cpp:78: error: no matching function for call to ... /opt/boost_1_54_0_icc/boost/property_map/parallel/ distributed_property_map.hpp:329: note: candidates are: boost::parallel::distributed_property_map<ProcessGroup, GlobalMap, StorageMap>::distributed_property_map(const ProcessGroup&, const GlobalMap&, const StorageMap&) Is this right arguments centrality_map(process_groupe, local_map) ? Or it must be: VertexKey<Graph> vertex_key; CentralityMap centrality_map = boost::parallel::make_distributed_property_map(process_groupe, local_map, vertex_key); In this case: network.cpp:78: instantiated from here /opt/boost_1_54_0_icc/boost/property_map/parallel/impl/distributed_property_map.ipp:140: error: request for member ‘first’ in ‘p’, which is of non-class type ‘double’ /opt/boost_1_54_0_icc/boost/property_map/parallel/impl/distributed_property_map.ipp:142: error: request for member ‘second’ in ‘p’, which is of non-class type ‘double’ /opt/boost_1_54_0_icc/boost/property_map/parallel/impl/distributed_property_map.ipp:142: error: request for member ‘second’ in ‘p’, which is of non-class type ‘double’ Any suggestions? Thanks.

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[boost-users][asio] Can't read socket
by Miklós Tóth 08 Jan '14

08 Jan '14

Hi Community, I've a problem with named-pipe communication. Please help me investigate this. I'm totally clueless now. I have a Connector class. I want to read some data from a socket. This is it: class Connector { public: Connector(boost::asio::io_service& io_service) : _io_service(io_service), _socket(io_service) { _endpoint.address(boost::asio::ip::address::from_string("127.0.0.1")); _endpoint.port(4242); _socket.async_connect(_endpoint, boost::bind(&Connector::handle_accept, this, boost::asio::placeholders::error)); } void close() { _io_service.post(boost::bind(&Connector::do_close, this)); _io_service.stop(); } private: void handle_accept(const boost::system::error_code& error) { if (error) { throw ConnectorError(_T("Cannot estabilish connection.")); } boost::asio::async_read(_socket, boost::asio::buffer(_readbuffer, 1024), boost::bind(&Connector::handle_read, this, boost::asio::placeholders::error)); } void handle_read(const boost::system::error_code& error) { if (!error) { if (_readbuffer.empty()) { boost::this_thread::sleep(boost::posix_time::milliseconds(100)); } else { std::string string_buffer; std::copy(_readbuffer.begin(), _readbuffer.end(), std::back_insert_iterator<std::string>(string_buffer)); std::cout << string_buffer << std::endl; _readbuffer.clear(); } boost::asio::async_read(_socket, boost::asio::buffer(_readbuffer, 1024), boost::bind(&Connector::handle_read, this, boost::asio::placeholders::error)); } } void do_close() { _socket.close(); } boost::asio::io_service& _io_service; boost::asio::ip::tcp::socket _socket; boost::asio::ip::tcp::endpoint _endpoint; std::vector<char> _readbuffer; }; This is how I use it: boost::asio::io_service io_service; Connector connector(io_service); boost::thread async_io_thread(boost::bind(&boost::asio::io_service::run, &io_service)); while (1) { //... stuff } connector.close(); async_io_thread.join(); But whenever I send a data package, this class is unable to read it from the socket. The readbuffer is always empty. I have a python code to test the sending application. import sys import socket s = socket.socket() address = '127.0.0.1' port = 4242 try: s.connect((address, port)) except Exception, e: sys.stdout.write('conn err %s:%d. exception: %s' % (address, port, `e`)) try: data = s.recv(1024) print data while True: more = s.recv(1024) print more if not more: break except Exception, e: sys.stdout.write('read err %s:%d. exception: is %s' % (address, port, `e`)) It works perfectly. As far as I know these the two code snippet should work the same. Clearly I'm missing something. Regards, Miklos

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GSoc 2k14
by Aman Jain 07 Jan '14

07 Jan '14

Hey, I wanna to do Gsoc this year by contributing to some C++ libraries and I am beginner. Actually, I want to contribute by modifying libraries I have once made some part of String library by myself using OOPS I have talked at IRC channel and according to my interest someone suggested me to contribute to https://github.com/boostorg/algorithm Can some one help me out how should I continue ? How to use git-hub here for contribution and bug fixing ? Regards, Aman

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[ANN] Registration for C++Now 2014 is Open
by Boris Kolpackov 07 Jan '14

07 Jan '14

Hi, Registration is now open for the eighth annual C++Now conference (formerly BoostCon) which will be held in Aspen, Colorado, USA, May 12th to 17th, 2014. C++Now is a general C++ conference for C++ experts and enthusiasts. It is not specific to any library/framework or compiler vendor and has three tracks with presentations ranging from hands-on, practical tutorials to advanced C++ design and development techniques. In particular, one of the tracks is dedicated exclusively to tutorials. Last year the conference sold out pretty quickly and we expect it to happen again this year. As a result, we encourage anyone interested in attending to register early. Additionally, early bird hotel reservations end January 10th. For more information on registering, visit: http://cppnow.org/2014/01/2014-registration-is-open/ For early bird hotel reservations, visit: http://cppnow.org/location/lodging/ For general information about the conference, visit: http://cppnow.org/about/ Boris

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[Boost Graph Library] read_graphviz example
by Robert Johannes Langenberg 07 Jan '14

07 Jan '14

Hello, I've recently started using the boost graph library to read a graph in dot format generated with pygraphviz and run some analysis on it. I get the basic example http://www.boost.org/doc/libs/1_55_0/libs/graph/doc/read_graphviz.html#exam… to compile, but it then segfaults when reading the file because it can't find the property "colors" (stack trace below). Now I understand that I didn't define this property but I also have no idea how to do it. Debugging it, i find the name="colors", key=0 and value="red" for the function call below: #11 0x000000010001b40c in boost::put<unsigned long, std::string> (name=@0x100205880, dp=@0x7fff5fbff5f8, key=@0x100204d78, value=@0x100205888) at dynamic_property_map.hpp:292 292 boost::shared_ptr<dynamic_property_map> new_map = dp.generate(name, key, value); For a general understanding of what's happening: What is "key" good for? In the example, where is the variable vertex_color declared? What is this "mass" property and why does it contain vertex_color? What is the type vertex_color_t? The documentation didn't help me, maybe there are easier starting points or i've just looked in the wrong parts of http://www.boost.org/doc/libs/1_55_0/libs/graph/doc/table_of_contents.html If someone could point me to a proper example/tutorial/documentation it'd be greatly appreciated. Best regards, Robert Langenberg Stacktrace: Program received signal SIGABRT, Aborted. 0x00007fff971e8d46 in __kill () (gdb) where #0 0x00007fff971e8d46 in __kill () #1 0x00007fff8fa28f83 in abort () #2 0x00007fff8f35c9eb in abort_message () #3 0x00007fff8f35a39a in default_terminate () #4 0x00007fff8df32887 in _objc_terminate () #5 0x00007fff8f35a3c9 in safe_handler_caller () #6 0x00007fff8f35a424 in std::terminate () #7 0x00007fff8f35b58b in __cxa_throw () #8 0x0000000100016eae in boost::throw_exception<boost::exception_detail::error_info_injector<boost::property_not_found> > (e=@0x7fff5fbfedb8) at throw_exception.hpp:70 #9 0x0000000100016ff0 in boost::exception_detail::throw_exception_<boost::property_not_found> (x=@0x7fff5fbfee90, current_function=0x100061188 "boost::shared_ptr<boost::dynamic_property_map> boost::dynamic_properties::generate(const std::string&, const Key&, const Value&) [with Key = long unsigned int, Value = std::basic_string<char, std::cha"..., file=0x100061008 "/Users/rlangenb/workspace/boost_1_55_0/boost/property_map/dynamic_property_map.hpp", line=268) at throw_exception.hpp:87 #10 0x000000010001ae6e in boost::dynamic_properties::generate<unsigned long, std::string> (this=0x7fff5fbff5f8, name=@0x100205880, key=@0x100204d78, value=@0x100205888) at dynamic_property_map.hpp:268 #11 0x000000010001b40c in boost::put<unsigned long, std::string> (name=@0x100205880, dp=@0x7fff5fbff5f8, key=@0x100204d78, value=@0x100205888) at dynamic_property_map.hpp:292 #12 0x000000010000bf4a in boost::detail::graph::mutate_graph_impl<boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, boost::property<boost::vertex_name_t, std::string, boost::property<boost::vertex_color_t, float, boost::no_property> >, boost::property<boost::edge_weight_t, double, boost::no_property>, boost::property<boost::graph_name_t, std::string, boost::no_property>, boost::listS> >::set_node_property (this=0x7fff5fbff340, key=@0x100205880, node=@0x1002063d0, value=@0x100205888) at graphviz.hpp:775 #13 0x000000010001f006 in boost::read_graphviz_detail::translate_results_to_graph (r=@0x7fff5fbff140, mg=0x7fff5fbff340) at read_graphviz_new.cpp:770

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Re: [Boost-users] [graph][BGL][PBGL] Use of dynamic_properties in parallel
by bminano 07 Jan '14

07 Jan '14

I have found the problem. It seems a cast problem in the dynamic_properties class. I have proposed a patch in the Ticket #9549. I am sorry, I am new to proposing patches so maybe that was not the correct way. -- View this message in context: http://boost.2283326.n4.nabble.com/graph-BGL-PBGL-Use-of-dynamic-properties… Sent from the Boost - Users mailing list archive at Nabble.com.

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How to create distributed_property_map
by Николай Кинаш 05 Jan '14

05 Jan '14

Hello. I try to calculate brandes_betweenness_centrality. #include <boost/graph/use_mpi.hpp> #include <boost/mpi/environment.hpp> #include <boost/mpi/communicator.hpp> #include <boost/graph/distributed/mpi_process_group.hpp> #include <boost/graph/parallel/process_group.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/distributed/adjacency_list.hpp> #include <boost/graph/small_world_generator.hpp> #include <boost/random/linear_congruential.hpp> #include <boost/graph/distributed/betweenness_centrality.hpp> #include <boost/graph/distributed/graphviz.hpp> #include <boost/graph/rmat_graph_generator.hpp> #include <boost/random/linear_congruential.hpp> #include <iostream> #include <algorithm> #include <math.h> using namespace boost; using namespace graph; using namespace distributed; namespace mpi = boost::mpi; typedef boost::adjacency_list<listS, distributedS<mpi_process_group,vecS>, undirectedS> Graph; typedef boost::unique_rmat_iterator<boost::minstd_rand, Graph> RMATGen; struct no_self_loops { no_self_loops() {} bool operator()(const std::pair<int,int>& e) { return e.first != e.second; } }; int main(int argc, char* argv[]) { boost::mpi::environment env(argc, argv); boost::minstd_rand gen; unsigned int SCALE = atoi(argv[1]); unsigned int EDGE_FACTOR = atoi(argv[2]); unsigned int N = pow(2, SCALE); unsigned int E = EDGE_FACTOR * N; Graph g( boost::make_filter_iterator<no_self_loops> ( RMATGen(gen, N, E, 0.45, 0.15, 0.15, 0.25), RMATGen()), boost::make_filter_iterator<no_self_loops>(RMATGen(), RMATGen()), N); typedef boost::property_map<Graph, vertex_index_t>::type LocalMap; boost::parallel::distributed_property_map<mpi_process_group, LocalMap, ||||||> centrality_map; //brandes_betweenness_centrality(g, centrality_map); } What should be here "|||||" ? I see http://www.boost.org/doc/libs/1_55_0/libs/graph_parallel/doc/html/distribut… template<typename ProcessGroup, typename LocalPropertyMap, typename Key, typename GhostCellS = gc_mapS> Key: The key_type of the distributed property map, which must model the Global Descriptor concept But don`t understand, is not work - typedef property_traits<LocalMap>::key_type key_type; Can you provide example?

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