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Diffstat (limited to 'src/Toplex_map/include/gudhi/Lazy_toplex_map.h')
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diff --git a/src/Toplex_map/include/gudhi/Lazy_toplex_map.h b/src/Toplex_map/include/gudhi/Lazy_toplex_map.h new file mode 100644 index 00000000..b0b3706e --- /dev/null +++ b/src/Toplex_map/include/gudhi/Lazy_toplex_map.h @@ -0,0 +1,271 @@ +/* This file is part of the Gudhi Library. The Gudhi library + * (Geometric Understanding in Higher Dimensions) is a generic C++ + * library for computational topology. + * + * Author: François Godi, Vincent Rouvreau + * + * Copyright (C) 2018 INRIA + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#ifndef LAZY_TOPLEX_MAP_H +#define LAZY_TOPLEX_MAP_H + +#include <gudhi/Toplex_map.h> +#include <boost/heap/fibonacci_heap.hpp> + +namespace Gudhi { + +/** + * \brief Lazy toplex map data structure for representing unfiltered simplicial complexes. + * + * \details A Toplex_map is an unordered map from vertices to maximal simplices (aka. toplices). + * The lazy version is not always up to date as it requires clean operation in order to be. + * + * \ingroup toplex_map */ +class Lazy_toplex_map { + public: + /** Vertex is the type of vertices. */ + using Vertex = Toplex_map::Vertex; + + /** Simplex is the type of simplices. */ + using Simplex = Toplex_map::Simplex; + + /** The type of the pointers to maximal simplices. */ + using Simplex_ptr = Toplex_map::Simplex_ptr; + + /** The type of the sets of Simplex_ptr. */ + using Simplex_ptr_set = Toplex_map::Simplex_ptr_set; + + /** Adds the given simplex to the complex. + * The simplex must not be in the complex already, and it must not contain one of the current toplices. */ + template <typename Input_vertex_range> + void insert_independent_simplex(const Input_vertex_range &vertex_range); + + /** \brief Adds the given simplex to the complex. + * Nothing happens if the simplex is already in the complex (i.e. it is a face of one of the toplices). */ + template <typename Input_vertex_range> + bool insert_simplex(const Input_vertex_range &vertex_range); + + /** \brief Removes the given simplex and its cofaces from the complex. + * Its faces are kept inside. */ + template <typename Input_vertex_range> + void remove_simplex(const Input_vertex_range &vertex_range); + + /** Does a simplex belong to the complex ? */ + template <typename Input_vertex_range> + bool membership(const Input_vertex_range &vertex_range); + + /** Do all the facets of a simplex belong to the complex ? */ + template <typename Input_vertex_range> + bool all_facets_inside(const Input_vertex_range &vertex_range); + + /** Contracts one edge in the complex. + * The edge has to verify the link condition if you want to preserve topology. + * Returns the remaining vertex. */ + Vertex contraction(const Vertex x, const Vertex y); + + /** \brief Number of maximal simplices. */ + std::size_t num_maximal_simplices() const { return size; } + + /** \brief Number of vertices. */ + std::size_t num_vertices() const { return t0.size(); } + + private: + template <typename Input_vertex_range> + void erase_max(const Input_vertex_range &vertex_range); + template <typename Input_vertex_range> + Vertex best_index(const Input_vertex_range &vertex_range); + void clean(const Vertex v); + + std::unordered_map<Vertex, std::size_t> gamma0_lbounds; + + std::unordered_map<Vertex, Simplex_ptr_set> t0; + bool empty_toplex; // Is the empty simplex a toplex ? + + typedef boost::heap::fibonacci_heap<std::pair<std::size_t, Vertex>> PriorityQueue; + PriorityQueue cleaning_priority; + std::unordered_map<Vertex, PriorityQueue::handle_type> cp_handles; + + std::size_t get_gamma0_lbound(const Vertex v) const; + + std::size_t size_lbound = 0; + std::size_t size = 0; + + const double ALPHA = 4; // time + const double BETTA = 8; // memory +}; + +template <typename Input_vertex_range> +void Lazy_toplex_map::insert_independent_simplex(const Input_vertex_range &vertex_range) { + for (const Vertex &v : vertex_range) + if (!gamma0_lbounds.count(v)) + gamma0_lbounds.emplace(v, 1); + else + gamma0_lbounds[v]++; + size_lbound++; + insert_simplex(vertex_range); +} + +template <typename Input_vertex_range> +bool Lazy_toplex_map::insert_simplex(const Input_vertex_range &vertex_range) { + Simplex sigma(vertex_range.begin(), vertex_range.end()); + // Check empty face management + empty_toplex = (sigma.size() == 0); + Simplex_ptr sptr = std::make_shared<Simplex>(sigma); + bool inserted = false; + for (const Vertex &v : sigma) { + if (!t0.count(v)) { + t0.emplace(v, Simplex_ptr_set()); + auto v_handle = cleaning_priority.push(std::make_pair(0, v)); + cp_handles.emplace(v, v_handle); + } + inserted = t0.at(v).emplace(sptr).second; + cleaning_priority.update(cp_handles.at(v), std::make_pair(t0.at(v).size() - get_gamma0_lbound(v), v)); + } + if (inserted) size++; + if (size > (size_lbound + 1) * BETTA) clean(cleaning_priority.top().second); + return inserted; +} + +template <typename Input_vertex_range> +void Lazy_toplex_map::remove_simplex(const Input_vertex_range &vertex_range) { + if (vertex_range.begin() == vertex_range.end()) { + t0.clear(); + gamma0_lbounds.clear(); + cleaning_priority.clear(); + size_lbound = 0; + size = 0; + empty_toplex = false; + } else { + const Vertex &v = best_index(vertex_range); + // Copy constructor needed because the set is modified + if (t0.count(v)) + for (const Simplex_ptr &sptr : Simplex_ptr_set(t0.at(v))) + if (included(vertex_range, *sptr)) { + erase_max(*sptr); + for (const Simplex &f : facets(vertex_range)) insert_independent_simplex(f); + } + } +} + +template <typename Input_vertex_range> +bool Lazy_toplex_map::membership(const Input_vertex_range &vertex_range) { + if (t0.size() == 0 && !empty_toplex) return false; // empty complex + if (vertex_range.begin() == vertex_range.end()) return true; // empty query simplex + Vertex v = best_index(vertex_range); + if (!t0.count(v)) return false; + for (const Simplex_ptr &sptr : t0.at(v)) + if (included(vertex_range, *sptr)) return true; + return false; +} + +template <typename Input_vertex_range> +bool Lazy_toplex_map::all_facets_inside(const Input_vertex_range &vertex_range) { + Simplex sigma(vertex_range.begin(), vertex_range.end()); + Vertex v = best_index(sigma); + if (!t0.count(v)) return false; + Simplex f = sigma; + f.erase(v); + if (!membership(f)) return false; + std::unordered_set<Vertex> facets_inside; + for (const Simplex_ptr &sptr : t0.at(v)) + for (const Vertex &w : sigma) { + f = sigma; + f.erase(w); + if (included(f, *sptr)) facets_inside.insert(w); + } + return facets_inside.size() == sigma.size() - 1; +} + +/* Returns the remaining vertex */ +Lazy_toplex_map::Vertex Lazy_toplex_map::contraction(const Vertex x, const Vertex y) { + if (!t0.count(x)) return y; + if (!t0.count(y)) return x; + Vertex k, d; + if (t0.at(x).size() > t0.at(y).size()) + k = x, d = y; + else + k = y, d = x; + // Copy constructor needed because the set is modified + for (const Simplex_ptr &sptr : Simplex_ptr_set(t0.at(d))) { + Simplex sigma(*sptr); + erase_max(sigma); + sigma.erase(d); + sigma.insert(k); + insert_simplex(sigma); + } + t0.erase(d); + return k; +} + +/* No facets insert_simplexed */ +template <typename Input_vertex_range> +inline void Lazy_toplex_map::erase_max(const Input_vertex_range &vertex_range) { + Simplex sigma(vertex_range.begin(), vertex_range.end()); + empty_toplex = false; + Simplex_ptr sptr = std::make_shared<Simplex>(sigma); + bool erased = false; + for (const Vertex &v : sigma) { + erased = t0.at(v).erase(sptr) > 0; + if (t0.at(v).size() == 0) t0.erase(v); + } + if (erased) size--; +} + +template <typename Input_vertex_range> +Lazy_toplex_map::Vertex Lazy_toplex_map::best_index(const Input_vertex_range &vertex_range) { + Simplex tau(vertex_range.begin(), vertex_range.end()); + std::size_t min = std::numeric_limits<size_t>::max(); + Vertex arg_min = -1; + for (const Vertex &v : tau) + if (!t0.count(v)) + return v; + else if (t0.at(v).size() < min) + min = t0.at(v).size(), arg_min = v; + if (min > ALPHA * get_gamma0_lbound(arg_min)) clean(arg_min); + return arg_min; +} + +std::size_t Lazy_toplex_map::get_gamma0_lbound(const Vertex v) const { + return gamma0_lbounds.count(v) ? gamma0_lbounds.at(v) : 0; +} + +void Lazy_toplex_map::clean(const Vertex v) { + Toplex_map toplices; + std::unordered_map<int, std::vector<Simplex>> dsorted_simplices; + std::size_t max_dim = 0; + for (const Simplex_ptr &sptr : Simplex_ptr_set(t0.at(v))) { + if (sptr->size() > max_dim) { + for (std::size_t d = max_dim + 1; d <= sptr->size(); d++) dsorted_simplices.emplace(d, std::vector<Simplex>()); + max_dim = sptr->size(); + } + dsorted_simplices[sptr->size()].emplace_back(*sptr); + erase_max(*sptr); + } + for (std::size_t d = max_dim; d >= 1; d--) + for (const Simplex &s : dsorted_simplices.at(d)) + if (!toplices.membership(s)) toplices.insert_independent_simplex(s); + Simplex sv; + sv.insert(v); + auto clean_cofaces = toplices.maximal_cofaces(sv); + size_lbound = size_lbound - get_gamma0_lbound(v) + clean_cofaces.size(); + gamma0_lbounds[v] = clean_cofaces.size(); + for (const Simplex_ptr &sptr : clean_cofaces) insert_simplex(*sptr); +} + +} // namespace Gudhi + +#endif /* LAZY_TOPLEX_MAP_H */ |