November 2013 - Boost-users

self_loop=false for Unique R-MAT generator
by Николай Кинаш 22 Nov '13

22 Nov '13

Hi. I use Parallel Boost Graph Library to create network Barabási–Albert (BA) model int main(int argc, char* argv[]) { boost::mpi::environment env(argc, argv); boost::minstd_rand gen; Graph g(RMATGen(gen, 100, 400, 0.3, 0.1, 0.2, 0.03), RMATGen(), 100); write_graphviz(std::cout, g); } This graph always have self-loops vertex. How i can to forbid self_loop for Unique R-MAT generator ?

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Re: [Boost-users] [BGL] visitors.hpp:138: error: no type named 'event_filter' in 'class dijkstra_custom_visitor'
by The Maschine 22 Nov '13

22 Nov '13

Hi, My code is very simple so I suspect I missing something about the real 'examine_vertex' meaning. One example with the custom visitor and one without that produces the correct results out site the 'search' (I;d like to be able to do it with a visitor though for later steps) Simplified to just the essentials. #### With VISITOR #### IndexMap indexMap = boost::get(boost::vertex_index, m_ugraph); PredecessorMap predecessorMap(&predecessors[0], indexMap); DistanceMap distanceMap(&distances[0], indexMap); glm::dvec3 s_mid = m_ugraph[*vertex_iterator_begin].m_mid_point; double thres = 500.0f; dijkstra_threshold vis(s_mid,thres); try { boost::dijkstra_shortest_paths(m_ugraph, *vertex_iterator_begin, boost::predecessor_map(predecessorMap).distance_map(distanceMap).visitor(vis)); } catch (...) { } int total_node_count2 = 0; double total_depth2 = 0.0; for (boost::tie(vi, vi_end) = boost::vertices(m_ugraph); vi != vi_end; ++vi) { if( (double(distances[*vi])*1.1) >= std::numeric_limits<double>::max() || (std::isnan(distances[*vi])) || !(std::isfinite(distances[*vi])) ) { } else { total_depth2 += double(distances[*vi]); total_node_count2 += 1; } } #### To the total distances and the number of nodes within the radius is not correct… #### Without a visitor outside dijkstra_shortest_paths #### try { boost::dijkstra_shortest_paths(m_ugraph, *vertex_iterator_begin, boost::predecessor_map(predecessorMap).distance_map(distanceMap)); } catch (...) { } int total_node_count2 = 0; double total_depth2 = 0.0; for (boost::tie(vi, vi_end) = boost::vertices(m_ugraph); vi != vi_end; ++vi) { if( (double(distances[*vi])*1.1) >= std::numeric_limits<double>::max() || (std::isnan(distances[*vi])) || !(std::isfinite(distances[*vi])) ) { } else { if( thres > 0.0f && glm::distance(s_mid, m_ugraph[*vi].m_mid_point) < thres ) { total_depth2 += double(distances[*vi]); total_node_count2 += 1; } } ### This give you the correct results but you searched the full graph. Any ideas? Thanks

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Visitor pattern with functor front end
by Daniele Barzotti 22 Nov '13

22 Nov '13

Hi, maybe this will be a trivial question but I'm quite new to MSM. If I would to use the visitor pattern, how can I define it using the functor front-end? Regards, Daniele.

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Boost.log file rotation current file name
by Daniel Krikun 22 Nov '13

22 Nov '13

Hello, I use some log viewer tool to display and filter logs. In log4j there is a feature that allows for the current logfile to have some constant name, e.g 'current.log', and only after it is finalized it is renamed to its name (probably having some timestamp/counter) in it. This feature makes it most convenient with log viewers. Is it possible to achieve this with Boost.Log? If not I would like to suggest it as a feature request. Regards,

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Fwd: Boost.log file collector
by Daniel Krikun 22 Nov '13

22 Nov '13

Hello, When I set up text_file_backend with file rotation and a file collector with the target directory other from the directory where my application resides, then if the application crashes, the current log file will not be collected to the target directory. This is somewhat inconvenient, because, let's say we setup the file collector to collect all the log files under 'logs' subfolder, and then if the application crashes we ask the user to simply e-mail the 'logs' folder to see what possibly went wrong before the crash, but, alas, the most interesting piece is missing. Is there a way to work around the problem? Thanks,

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[multiprecision] Empty intervals and intervals with NaN check
by Александров Петр 21 Nov '13

21 Nov '13

Hello. In MPFI documentation it is said that "MPFI functions operate on valid intervals ..., their behavior with non-valid intervals as input is undefined". Are intervals checked in Boost Multiprecision library whether they are invalid? Can this be easily done using Boost? Kind regards, Petr.

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Problem with variadic BOOST_PP_TUPLE_REM in Clang
by Jeremiah Willcock 21 Nov '13

21 Nov '13

When using Clang version "Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)" in C++11 mode, the code: #include <boost/preprocessor.hpp> BOOST_PP_TUPLE_REM()(foo(bar, baz) const) is not expanded correctly. The second line expands to: BOOST_PP_TUPLE_REM_(foo(bar, baz) const) while on GCC 4.9, it expands to: foo(bar, baz) const Is there a known issue with this macro on Clang? -- Jeremiah Willcock

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Re: [Boost-users] [BGL] visitors.hpp:138: error: no type named 'event_filter' in 'class dijkstra_custom_visitor'
by The Maschine 21 Nov '13

21 Nov '13

Thanks a lot for that. Problem solved, in terms of the function call. What remains is that my custom visitor is not behaving as I thought** it would! What I wanted to implement (which partially is based on an older thread that you replied) is cut-off radius around the source. The problem with my version of visitor is that it dies when it 'examines' the first vertex outside the radius, but this doesnt imply that everything within radium is correctly found (correct distances etc). Any tips about this? Thanks a lot

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[BGL] visitors.hpp:138: error: no type named 'event_filter' in 'class dijkstra_custom_visitor'
by The Maschine 21 Nov '13

21 Nov '13

Hi, Im trying to use a custom visitor but I get this error. My custom visitor is: class dijkstra_custom_visitor : public boost::default_dijkstra_visitor { public: dijkstra_threshold(glm::dvec3 source, double threshold): s(source), threshold(threshold) {} struct hit_threshold {}; void examine_vertex(boost::graph_traits <unGraph>::vertex_descriptor v, const unGraph& g) { glm::dvec3 dest = boost::get(&VertexProperties::m_mid_point, g, v); if( glm::distance(s,dest) > threshold ) throw hit_threshold(); } double threshold; glm::dvec3 s; }; My 'calling' line is: std::vector<Vertex> predecessors(boost::num_vertices(m_ugraph)); std::vector<Weight> distances(boost::num_vertices(m_ugraph), std::numeric_limits<double>::max() ); IndexMap indexMap = boost::get(boost::vertex_index, m_ugraph); PredecessorMap predecessorMap(&predecessors[0], indexMap); DistanceMap distanceMap(&distances[0], indexMap); glm::dvec3 s_mid = m_ugraph[*vertex_iterator_begin].m_mid_point; double thres = 500.0f; boost::dijkstra_shortest_paths(m_ugraph, *vertex_iterator_begin, boost::predecessor_map(predecessorMap).distance_map(distanceMap).visitor(boost::make_dijkstra_visitor(dijkstra_custom_visitor(s_mid,thres)))); What do you think is the problem? thanks

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TypeTraits like library for inheritance access specifiers?
by Mostafa 21 Nov '13

21 Nov '13

Is there a TypeTraits like library for determining inheritance access specificers? Something like a is_private_base_of? Thanks, Mostafa

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