From 78ccc10eb0034a4648df303f2913b6b4680b085e Mon Sep 17 00:00:00 2001 From: Marc Glisse Date: Fri, 6 Mar 2020 17:35:38 +0100 Subject: Generators for simplex tree --- src/Simplex_tree/include/gudhi/Simplex_tree.h | 86 +++++++++++++++++++++- .../gudhi/Simplex_tree/Simplex_tree_iterators.h | 12 +-- 2 files changed, 86 insertions(+), 12 deletions(-) (limited to 'src/Simplex_tree/include/gudhi') diff --git a/src/Simplex_tree/include/gudhi/Simplex_tree.h b/src/Simplex_tree/include/gudhi/Simplex_tree.h index 76608008..7315bf45 100644 --- a/src/Simplex_tree/include/gudhi/Simplex_tree.h +++ b/src/Simplex_tree/include/gudhi/Simplex_tree.h @@ -24,6 +24,7 @@ #include #include #include +#include #ifdef GUDHI_USE_TBB #include @@ -246,8 +247,8 @@ class Simplex_tree { * which is consequenlty * equal to \f$(-1)^{\text{dim} \sigma}\f$ the canonical orientation on the simplex. */ - Simplex_vertex_range simplex_vertex_range(Simplex_handle sh) { - assert(sh != null_simplex()); // Empty simplex + Simplex_vertex_range simplex_vertex_range(Simplex_handle sh) const { + GUDHI_CHECK(sh != null_simplex(), "empty simplex"); return Simplex_vertex_range(Simplex_vertex_iterator(this, sh), Simplex_vertex_iterator(this)); } @@ -450,6 +451,15 @@ class Simplex_tree { return true; } + /** \brief Returns the filtration value of a simplex. + * + * Same as `filtration()`, but does not handle `null_simplex()`. + */ + static Filtration_value filtration_(Simplex_handle sh) { + GUDHI_CHECK (sh != null_simplex(), "null simplex"); + return sh->second.filtration(); + } + public: /** \brief Returns the key associated to a simplex. * @@ -827,7 +837,7 @@ class Simplex_tree { /** Returns the Siblings containing a simplex.*/ template - Siblings* self_siblings(SimplexHandle sh) { + static Siblings* self_siblings(SimplexHandle sh) { if (sh->second.children()->parent() == sh->first) return sh->second.children()->oncles(); else @@ -1465,6 +1475,76 @@ class Simplex_tree { } } + /** \brief Returns a vertex of `sh` that has the same filtration value as `sh` if it exists, and `null_vertex()` otherwise. + * + * For a lower-star filtration built with `make_filtration_non_decreasing()`, this is a way to invert the process and find out which vertex had its filtration value propagated to `sh`. + * If several vertices have the same filtration value, the one it returns is arbitrary. */ + Vertex_handle vertex_with_same_filtration(Simplex_handle sh) { + auto filt = filtration_(sh); + for(auto v : simplex_vertex_range(sh)) + if(filtration_(find_vertex(v)) == filt) + return v; + return null_vertex(); + } + + /** \brief Returns an edge of `sh` that has the same filtration value as `sh` if it exists, and `null_simplex()` otherwise. + * + * For a flag-complex built with `expansion()`, this is a way to invert the process and find out which edge had its filtration value propagated to `sh`. + * If several edges have the same filtration value, the one it returns is arbitrary. + * + * \pre `sh` must have dimension at least 1. */ + Simplex_handle edge_with_same_filtration(Simplex_handle sh) { +#if 0 + // FIXME: Only do this if dim >= 2, since we don't want to return a vertex... + // Test if we are lucky and the parent has the same filtration value. + Siblings* sib = self_siblings(sh); + Vertex_handle v_par = sib->parent(); + sib = sib->oncles(); + Simplex_handle par = sib->find(v_par); + if(filtration_(par) == filt) return edge_with_same_filtration(par); +#endif + auto&& vertices = simplex_vertex_range(sh); + auto end = std::end(vertices); + auto vi = std::begin(vertices); + GUDHI_CHECK(vi != end, "empty simplex"); + auto v0 = *vi; + ++vi; + GUDHI_CHECK(vi != end, "simplex of dimension 0"); + if(std::next(vi) == end) return sh; // shortcut for dimension 1 + boost::container::static_vector suffix; + suffix.push_back(v0); + auto filt = filtration_(sh); + do + { + Vertex_handle v = *vi; + auto&& children1 = find_vertex(v)->second.children()->members_; + for(auto w : suffix){ + // Can we take advantage of the fact that suffix is ordered? + Simplex_handle s = children1.find(w); + if(filtration_(s) == filt) + return s; + } + suffix.push_back(v); + } + while(++vi != end); + return null_simplex(); + } + + /** \brief Returns an edge of `sh` that has the same filtration value as `sh` if it exists, and `null_simplex()` otherwise. + * + * For a flag-complex built with `expansion()`, this is a way to invert the process and find out which edge had its filtration value propagated to `sh`. + * If several edges have the same filtration value, the one it returns is arbitrary. */ + Simplex_handle minimal_simplex_with_same_filtration(Simplex_handle sh) { + if(dimension(sh) == 0) // vertices are minimal + return sh; + auto filt = filtration_(sh); + // Naive implementation, it can be sped up. + for(auto b : boundary_simplex_range(sh)) + if(filtration_(b) == filt) + return minimal_simplex_with_same_filtration(b); + return sh; // None of its faces has the same filtration. + } + private: Vertex_handle null_vertex_; /** \brief Total number of simplices in the complex, without the empty simplex.*/ diff --git a/src/Simplex_tree/include/gudhi/Simplex_tree/Simplex_tree_iterators.h b/src/Simplex_tree/include/gudhi/Simplex_tree/Simplex_tree_iterators.h index efccf2f2..9007b6bd 100644 --- a/src/Simplex_tree/include/gudhi/Simplex_tree/Simplex_tree_iterators.h +++ b/src/Simplex_tree/include/gudhi/Simplex_tree/Simplex_tree_iterators.h @@ -15,9 +15,7 @@ #include #include -#if BOOST_VERSION >= 105600 -# include -#endif +#include #include @@ -42,13 +40,13 @@ class Simplex_tree_simplex_vertex_iterator : public boost::iterator_facade< typedef typename SimplexTree::Siblings Siblings; typedef typename SimplexTree::Vertex_handle Vertex_handle; - explicit Simplex_tree_simplex_vertex_iterator(SimplexTree * st) + explicit Simplex_tree_simplex_vertex_iterator(SimplexTree const* st) : // any end() iterator sib_(nullptr), v_(st->null_vertex()) { } - Simplex_tree_simplex_vertex_iterator(SimplexTree * st, Simplex_handle sh) + Simplex_tree_simplex_vertex_iterator(SimplexTree const* st, Simplex_handle sh) : sib_(st->self_siblings(sh)), v_(sh->first) { } @@ -166,15 +164,11 @@ class Simplex_tree_boundary_simplex_iterator : public boost::iterator_facade< // Most of the storage should be moved to the range, iterators should be light. Vertex_handle last_; // last vertex of the simplex Vertex_handle next_; // next vertex to push in suffix_ -#if BOOST_VERSION >= 105600 // 40 seems a conservative bound on the dimension of a Simplex_tree for now, // as it would not fit on the biggest hard-drive. boost::container::static_vector suffix_; // static_vector still has some overhead compared to a trivial hand-made // version using std::aligned_storage, or compared to making suffix_ static. -#else - std::vector suffix_; -#endif Siblings * sib_; // where the next search will start from Simplex_handle sh_; // current Simplex_handle in the boundary SimplexTree * st_; // simplex containing the simplicial complex -- cgit v1.2.3