rand_arrangements.hpp

/*********************************************************************
 *
 * Linear Arrangement Library - A library that implements a collection
 * algorithms for linear arrangments of graphs.
 *
 * Copyright (C) 2019 - 2023
 *
 * This file is part of Linear Arrangement Library. The full code is available
 * at:
 *      https://github.com/LAL-project/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/linear_arrangement.hpp>
#include <lal/graphs/graph.hpp>
 
namespace lal {
namespace generate {
 
class rand_arrangements {
public:
    rand_arrangements(const lal::graphs::graph& g, uint64_t seed = 0) noexcept
        : rand_arrangements(g.get_num_nodes(), seed)
    { }
 
    rand_arrangements(uint64_t n, uint64_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);
        }
        m_arr.identity();
    }
 
    const linear_arrangement& get_arrangement() noexcept {
        std::shuffle(m_arr.begin_direct(), m_arr.end_direct(), m_gen);
        m_arr.update_inverse();
        return m_arr;
    }
 
    const linear_arrangement& yield_arrangement() noexcept {
        return get_arrangement();
    }
 
private:
    const uint64_t m_n;
    std::mt19937 m_gen;
    linear_arrangement m_arr;
};
 
} // -- namespace generate
} // -- namespace lal