rand_arrangements.hpp

/*********************************************************************
 *
 *  Linear Arrangement Library - A library that implements a collection
 *  algorithms for linear arrangments of graphs.
 *
 *  Copyright (C) 2019 - 2021
 *
 *  This file is part of Linear Arrangement Library. To see the full code
 *  visit the webpage:
 *      https://github.com/lluisalemanypuig/linear-arrangement-library.git
 *
 *  Linear Arrangement Library is free software: you can redistribute it
 *  and/or modify it under the terms of the GNU Affero General Public License
 *  as published by the Free Software Foundation, either version 3 of the
 *  License, or (at your option) any later version.
 *
 *  Linear Arrangement Library 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with Linear Arrangement Library.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  Contact:
 *
 *      Lluís Alemany Puig (lalemany@cs.upc.edu)
 *          LARCA (Laboratory for Relational Algorithmics, Complexity and Learning)
 *          CQL (Complexity and Quantitative Linguistics Lab)
 *          Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *          Webpage: https://cqllab.upc.edu/people/lalemany/
 *
 *      Ramon Ferrer i Cancho (rferrericancho@cs.upc.edu)
 *          LARCA (Laboratory for Relational Algorithmics, Complexity and Learning)
 *          CQL (Complexity and Quantitative Linguistics Lab)
 *          Office S124, Omega building
 *          Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *          Webpage: https://cqllab.upc.edu/people/rferrericancho/
 *
 ********************************************************************/
 
#pragma once
 
// C++ includes
#include <algorithm>
#include <random>
 
// lal includes
#include <lal/graphs/graph.hpp>
 
namespace lal {
namespace generate {
 
class rand_arrangements {
public:
    rand_arrangements(const lal::graphs::graph& g, uint32_t seed = 0) noexcept
        : rand_arrangements(g.get_num_nodes(), seed)
    { }
 
    rand_arrangements(uint32_t n, uint32_t seed = 0) noexcept
        : m_n(n),
          m_arr(linear_arrangement(m_n))
    {
        if (seed == 0) {
            std::random_device rd;
            m_gen = std::mt19937(rd());
        }
        else {
            m_gen = std::mt19937(seed);
        }
        std::iota(m_arr.begin(), m_arr.end(), 0);
    }
 
    const linear_arrangement& get_arrangement() noexcept {
        std::shuffle(m_arr.begin(), m_arr.end(), m_gen);
        return m_arr;
    }
 
    inline const linear_arrangement& yield_arrangement() noexcept {
        return get_arrangement();
    }
 
private:
    const uint32_t m_n;
    std::mt19937 m_gen;
    linear_arrangement m_arr;
};
 
} // -- namespace generate
} // -- namespace lal