September 2006 - Boost-users - lists.preview.boost.org

[Boost][Graph] Reversing a directed edge
by Young, Michael 20 Sep '06

20 Sep '06

I am a newbie to BGL - actually, I'm just beginning to build examples with it. However, I have read the first 4 chapters of "the book", and I've searched the documentation, and I haven't seen a way to reverse a specific edge within a directed (bidirectional) graph. Is there anyway to do this without removing the original edge and then adding the "reversed" edge? I have an application that requires such a "flip" of particular edges at times, but remove/add seems to be a bit "heavyweight" in terms of computation, especially when I already have identified the edge and have it accessible via an iterator. Thanks, Mike

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Re: [Boost-users] [graph] breadth_first_search with a structure
by boost＠daniel-gohlke.de 20 Sep '06

20 Sep '06

Hello Stephan, with your example I get the same errors like before. The compiler is Visual C++ 6.0 and the version number ob boost is (probably) 1.33.1. The first errors I get are: H:\daten\Programme\boost/pending/property.hpp(40) : error C2039: 'kind' : is not a member of '`global namespace'' H:\daten\Programme\boost/graph/properties.hpp(198) : see reference to class template instantiation 'boost::property_kind<long dreiDmatrix::Vertex::*>' being compiled H:\daten\Programme\Matrizen\dreiDmatrix.h(78) : see reference to class template instantiation 'boost::property_map<class boost::adjacency_list<struct boost::vecS,struct boost::vecS,struct boost::undirectedS,struct dreiDmatrix::Vertex,struct boost::no_property,struct boost::no_property,struct boost::listS>,long dreiDmatrix::Vertex::*>' being compiled This error is several times repeated. CU Daniel Am 12.09.2006 um 17:36 Uhr haben Sie geschrieben: > Please try this one (it's the altered bfs-example): > > #include <boost/graph/adjacency_list.hpp> > #include <boost/graph/breadth_first_search.hpp> > #include <boost/pending/integer_range.hpp> > #include <iostream> > > using namespace boost; > > //tag for throwing inside bfs_distance_visitor > struct max_distance_reached{}; > template < typename DistanceMap > > class bfs_distance_visitor:public default_bfs_visitor { > typedef typename property_traits < DistanceMap >::value_type T; > > public: > bfs_distance_visitor(DistanceMap dmap, T > max_distance):m_distance_map(dmap),m_max_distance(max_distance){ } > template < typename Edge, typename Graph > > void tree_edge(Edge e, const Graph & g) const > { > typename graph_traits < Graph >::vertex_descriptor > s = source(e, g), t = target(e, g); > m_distance_map[t] = m_distance_map[s] + 1; > if (m_distance_map[t] >= m_max_distance) > throw max_distance_reached(); > } > DistanceMap m_distance_map; > T m_max_distance; > }; > > //own vertex, bundles properties style > struct Vertex{ > long distance; > double probability; > }; > > int > main() > { > // Select the graph type we wish to use > typedef adjacency_list < vecS, vecS, undirectedS, Vertex> graph_t; > // Set up the vertex IDs and names > enum { r, s, t, u, v, w, x, y, N }; > // Specify the edges in the graph > typedef std::pair < int, int >E; > E edge_array[] = { E(r, s), E(r, v), E(s, w), E(w, r), E(w, t), > E(w, x), E(x, t), E(t, u), E(x, y), E(u, y) > }; > > // Create the graph object > const int n_edges = sizeof(edge_array) / sizeof(E); > typedef graph_traits<graph_t>::vertices_size_type v_size_t; > graph_t g(edge_array, edge_array + n_edges, v_size_t(N)); > > // Typedefs > typedef graph_traits < graph_t >::vertex_descriptor vertex_descriptor ; > typedef graph_traits < graph_t >::vertices_size_type vertices_size_type; > > // get the distance property map from the graph > typedef property_map<graph_t, long Vertex::*>::type tDistanceMap; > tDistanceMap distance_map = get(&Vertex::distance, g); > > //create a bfs visitor which calculates all distances smaller than 3 > bfs_distance_visitor<tDistanceMap> vis(distance_map, 3); > try{ > breadth_first_search(g, vertex(s, g), visitor(vis)); > } catch(max_distance_reached& ){} > return EXIT_SUCCESS; > } > > If this won't compile, please specify also which version of boost and > VC++ you are using. > > HTH, > Stephan > _______________________________________________ > Boost-users mailing list > <a href='email_neu.php?writeTo=Boost-users(a)lists.boost.org'>Boost-users(a)lists.boost.org</a> > <a href='http://lists.boost.org/mailman/listinfo.cgi/boost-users<br' target='_blank'>http://lists.boost.org/mailman/listinfo.cgi/boost-users<br</a> /> > > >

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program_options, description string formatting question
by Ed Johnson 20 Sep '06

20 Sep '06

Hi, Is it possible to generate a description in the following format using program_options? It is a more compact format than the program_options default. It helps keep the left hand column's max length smaller, thus preventing some excess wrapping in the description column. Compact format: [-h/--help] display usage [-p/--purpose arg] model-selection or prediction [model-selection] -d/--drug arg HIV drug to be tested [-t/--thresholds arg] low and high thresholds for drug resistance Please use only one or two values. [10] Program Options Default: -h [ --help ] display usage -p [ --purpose ] arg (=model-selection) model-selection or prediction -d [ --drug ] arg HIV drug to be tested -t [ --thresholds ] arg Thresholds for high and low resistance . Please use only 1 thresholds. In the compact case, drug is a required option, but the others are optional. So, drug does not get brackets. Also, default arguments are placed brackets at the end of the descriptor. Such as, [10] for thresholds Thanks, Ed

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Boost.Wave compiling issue
by Edmond Gheury 20 Sep '06

20 Sep '06

Hi, when trying to compile Boost.Wave (1.33.1) on AIX with VACPP 6. I got an error located in the file \boost\wave\cpplexer\re2clex\cpp_re2c_lexer.hpp, line 307, i.e. lexer<IteratorT, PositionT> lexer; First, it seems strange that a variable name matches a type name (and that's what's teeling the error message). When I replace that variable name by "lexer_" and its three remaining occurences in the "lex_functor" class, there's no more errors. So, I wonder if it is a bug popping up only on some compilers and, btw, can someone give me an explanation of how it manages to compile on msvc and g++. Thank you very much. Regards, Edmond

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[bind] Problem when bind a templated member function
by Christian Henning 19 Sep '06

19 Sep '06

Hi there, I know it must be very easy but I cannot figure it out myself. Can somehow please take a look at: class task { public: template < class T > void do_it( const T t ) { thread_ptr.reset( new boost::thread( boost::bind( (void (thread::*)(const T)) &thread::_run , this ))); } private: template < class T > void _run( const T t ) {} private: typedef boost::shared_ptr< boost::thread > thread_ptr_t; thread_ptr_t thread_ptr; }; There must be something wrong. I'm using VC2003. The comiler tells me: c:\boost\boost\bind\bind_template.hpp(18) : error C2091: function returns function Thanks ahead, Christian

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Global mutex and boost.thread
by Daher 19 Sep '06

19 Sep '06

I need to perform disk activity to a shared file across multiple instances of my program... my program was originally written using windows API and I'm porting it to other systems. and I'm using boost.thread for my threads.. Any way to create a global mutex? on windows all you need to do is provide "Global\" Prefix to the mutex name. Any ideas will be appreciated. Thanks in advanced. Dee

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converting value before inserting into a list
by Alexander Shyrokov 19 Sep '06

19 Sep '06

I want to convert values according to a map before inserting it into the list. What is a proper way to do that? I have this: map<int,int> m; vector<int> a,b; for(vector<int>const_iterator i=a.begin();i!=a.end();++i) b.push_back(m[*i]); I could use std::copy with std::back_inserter to add elements to b, but how do I convert it first? Should I write my own version of back_inserter for that? copy(a.begin(),a.end(),my_back_inserter(b,m)); Thanks. -- Regards, Alexander. http://sjcomp.com

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Re: [Boost-users] converting value before inserting into a list
by Hughes, James 19 Sep '06

19 Sep '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Alexander Shyrokov > Sent: 19 September 2006 14:19 > To: boost-users(a)lists.boost.org > Subject: [Boost-users] converting value before inserting into a list > > I want to convert values according to a map before inserting > it into the list. What is a proper way to do that? > I have this: > > map<int,int> m; > vector<int> a,b; > > for(vector<int>const_iterator i=a.begin();i!=a.end();++i) > b.push_back(m[*i]); > > I could use std::copy with std::back_inserter to add elements > to b, but how do I convert it first? Should I write my own > version of back_inserter for that? > > copy(a.begin(),a.end(),my_back_inserter(b,m)); > > Thanks. > -- > Regards, > Alexander. http://sjcomp.com > _______________________________________________ I probably being very anti-modern C++ here, but I think that the for loop takes a lot of beating for readability......its probably the most efficient too (with a bit of cacheing of invarients)...... I do find that some of these so called 'helpers' do make the code more obscure, but that's perhaps because I have spent 15 years doing C then C++, rather than solely starting with C++. James > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > This message (including any attachments) contains confidential and/or proprietary information intended only for the addressee. Any unauthorized disclosure, copying, distribution or reliance on the contents of this information is strictly prohibited and may constitute a violation of law. If you are not the intended recipient, please notify the sender immediately by responding to this e-mail, and delete the message from your system. If you have any questions about this e-mail please notify the sender immediately.

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Re: [Boost-users] [serialization] Purpose of load_construct_data (was: Re: Library Interface Design)
by JOAQUIN LOPEZ MU?Z 19 Sep '06

19 Sep '06

Hello Robert, ----- Mensaje original ----- De: Robert Ramey <ramey(a)rrsd.com> Fecha: Sábado, Septiembre 16, 2006 9:00 am Asunto: Re: [Boost-users] [serialization] Purpose of load_construct_data (was: Re: Library Interface Design) > > I am not sure. I'm a little puzzled about the intended purpose of > > load_construct_data, as the docs and the code of Boost.Serialization > > seem to suggest that it is used for two incompatible tasks: > > > > a) to construct a dummy object prior to deserialization itself, thus > > providing a user-overridable hook in case default construction > is not > > appropriate. > > b) to deserialize in place as explained on the bit you quote. > > > > The intended purpose was to address de-serialization of objects > that have no default constructor. See test_non_default_ctor. > > > My hunch is that Robert started this with b) in mind but finally the > > facility was kept playing a more humble role as a). Consider for > > instance, serialization of pointers: currently, if an object > instance> is saved exclusively through pointers, > Boost.Serialization does the > > following when the first such > > pointer is met > > > > save_construct_data(ar,p); // S(0) > > ar<<*p; // S(1) > > > > and correspondingly at loading time > > > > p=get unitialized storage; > > load_construct_data(ar,p); // L(0) > > ar>>*p; // L(1) > > > > By default save_construct_data does nothing and load_construct_data > > creates a default cted object, effectively leading to a two-phase > > construction scenario. Now, if the user decides to override > > (save|load)_construct_data > > for some class, say foo, so as to perform one-phase construction, > > we've got the following: > > > > S(0) saves foo contents > > S(1) saves foo contents again > > Nope. save_construct_data saves ONLY that data needed for > constructionwhile ar << *p save that data NOT used in construction. > > > L(0) loads foo contents and creates a foo object with these. > > L(1) loads foo contents again > > Nope - see above. > > I believe this is well illustrated by the > test_non_default_ctor.cpp example > previously cited. > > Note that in generally, the data required to construct an instance > might not > be part of the instance itself. This is also addressed by this api. > > I'm not sure, but I suspect this could be also useful in de- > serializationof objects which contain references to other objects > as references can > only be set at object construction time. Tracking would still work. > Thanks for pointing me to test_non_default_ctor.cpp. I think this example nicely illustrates the purposes which (load|save)_construct_data is meant to serve, and that you've summarized in your comments above: * handle types without a default ctor. * serialize data used at construction time which are *not* serialized by T::serialize. and this is all good, but if I'm understanding you right then you're stating (in agreement with my analysis) that (load|save)_construct_data can't be used for one-phase serialization, and that two phases (construction and serialization) are still needed. The original post by Dave said otherwise, though, and I think the misunderstanding comes from the example at http://boost.org/libs/serialization/doc/serialization.html#constructors where my_class serializes my_class::m *both* at my_class::serialize *and* my_class::(load|save)_construct_data. If the analysis I develop in my previous post is correct (is it?) this leads to my_class::m being serialized *twice* when a pointer to my_class is saved. Maybe it would sufice to rewrite this part of the documentation with a more sensible example like the one at test_non_default_ctor.cpp. What do you think? > Robert Ramey Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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In reply to: " edge function"
by Tom Lenaerts 19 Sep '06

19 Sep '06

Hi stephan, sorry about the lack of detail in my question. Below you can find the code for a network factory class. The code reads a file (like this) 300 0 37 0 1 2 3 4 5 6 8 9 15 17 21 42 44 51 56 63 66 77 84 86 93 123 126 128 129 151 153 163 164 170 219 225 240 247 261 288 290 1 12 0 0 2 11 18 33 47 66 95 127 192 209 211 2 51 0 1 0 3 5 6 7 8 10 12 13 14 15 16 17 19 25 27 31 35 36 38 49 78 79 81 84 88 91 93 104 111 139 156 169 175 178 188 203 208 223 227 243 247 249 253 255 266 267 268 282 286 3 8 0 2 0 4 29 42 55 62 257 4 11 0 3 0 18 34 52 59 108 139 216 235 296 5 14 0 2 0 26 50 56 58 71 74 80 186 191 193 194 283 6 14 0 0 2 7 16 30 34 46 57 101 141 174 198 215 291 7 6 0 2 6 67 82 97 181 ... and when the member function 'create' is called, the network should be returned. The error was a runtime error. I got the following answer from Xcode: [Session started at 2006-09-19 09:57:00 +0200.] #seed.in not found. Creating a new seed... seed = 583597 gamenetwork has exited due to signal 10 (SIGBUS). I examined your code and adapted mine to yours and noticed that the error disappears when I change g=new Graph(); to g=new Graph(1); in the member function parseFile. It seems that this is the error that I made (as I expected it is a silly one). Could you tell me why the '1' is required here? Thanks for the help Tom ==networkfact.h #ifndef __NETWORKFACTORY_H #define __NETWORKFACTORY_H #include "factory.h" #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graph_traits.hpp> using namespace std; typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS> Graph; typedef Graph* Graphptr; typedef boost::graph_traits<Graph>::edge_descriptor Edge; typedef boost::graph_traits<Graph>::vertex_descriptor Vertex; typedef boost::graph_traits<Graph>::vertex_iterator Vertex_iterator; typedef boost::graph_traits<Graph>::edge_iterator Edge_iterator; typedef boost::graph_traits<Graph>::vertices_size_type Vertex_type; typedef boost::property_map<Graph, boost::vertex_index_t>::type IndexMap; typedef Factory<Graph> GraphFactory; // the factory creates new graph instances class NetworkFactory: public GraphFactory { public: NetworkFactory(string fname): _fname(fname){}; //the file contains a grpah specification. ~NetworkFactory(){}; Graphptr create(); private: Graphptr parseFile(istream&); void tokenize(const string&, vector<string>&, const string& delimiters = " "); void processTokens(vector<string>&, Graphptr); string _fname; }; typedef NetworkFactory* NetworkFactoryptr; #endif ==networkfact.cpp #include "networkfact.h" #include <boost/lexical_cast.hpp> #include <sstream> #include <fstream> Graphptr NetworkFactory::parseFile(istream& is){ char c; int numnodes=0; Graphptr g=NULL; while(!is.eof()){ c=is.get(); if(c=='#' || c == '\n'|| c == ' '){ string line; getline(is,line,'\n'); //ignore line content } else{ //it is not a comment line but useful information. is.putback(c); string line; getline(is,line,'\n'); //start parsing the line vector<string> tokens; tokenize(line,tokens); if(tokens.size() == 1){ numnodes= boost::lexical_cast<int>(tokens[0]); g=new Graph(1); } else { if(g!=NULL) processTokens(tokens,g); } } } return g; } void NetworkFactory::tokenize(const string& str, vector<string>& tokens, const string& delimiters){ // Skip delimiters at beginning. string::size_type lastPos = str.find_first_not_of(delimiters, 0); // Find first "non-delimiter". string::size_type pos = str.find_first_of(delimiters, lastPos); while (string::npos != pos || string::npos != lastPos) { // Found a token, add it to the vector. tokens.push_back(str.substr(lastPos, pos - lastPos)); // Skip delimiters. Note the "not_of" lastPos = str.find_first_not_of(delimiters, pos); // Find next "non-delimiter" pos = str.find_first_of(delimiters, lastPos); } } void NetworkFactory::processTokens(vector<string>& tokens, Graphptr g){ if(tokens.size()>=3){ int current = boost::lexical_cast<int>(tokens[0]); int numedges = boost::lexical_cast<int>(tokens[1]); Vertex first=boost::vertex(current,*g); for(int i=0;i<numedges;i++){ int other= boost::lexical_cast<int>(tokens[3+i]); //this has to be 3 because some other data is in position 2 Vertex second=boost::vertex(other,*g); pair<Edge, bool> result=boost::edge(first,second,*g); if(!result.second){ boost::add_edge(first,second,*g); } } } } Graphptr NetworkFactory::create(){ ifstream netwfile(_fname.c_str()); if(netwfile.is_open()){ Graphptr res= parseFile(netwfile); netwfile.close(); return res; } return NULL; }

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