utils_random_tpl.h

Go to the documentation of this file.

/****************************************************************************
 *   This file is part of the aGrUM/pyAgrum library.                        *
 *                                                                          *
 *   Copyright (c) 2005-2026 by                                             *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
 *                                                                          *
 *   The aGrUM/pyAgrum library is free software; you can redistribute it    *
 *   and/or modify it under the terms of either :                           *
 *                                                                          *
 *    - the GNU Lesser General Public License as published by               *
 *      the Free Software Foundation, either version 3 of the License,      *
 *      or (at your option) any later version,                              *
 *    - the MIT license (MIT),                                              *
 *    - or both in dual license, as here.                                   *
 *                                                                          *
 *   (see https://agrum.gitlab.io/articles/dual-licenses-lgplv3mit.html)    *
 *                                                                          *
 *   This aGrUM/pyAgrum library is distributed in the hope that it will be  *
 *   useful, but WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,          *
 *   INCLUDING BUT NOT LIMITED TO THE WARRANTIES MERCHANTABILITY or FITNESS *
 *   FOR A PARTICULAR PURPOSE  AND NONINFRINGEMENT. IN NO EVENT SHALL THE   *
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,        *
 *   ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR  *
 *   OTHER DEALINGS IN THE SOFTWARE.                                        *
 *                                                                          *
 *   See LICENCES for more details.                                         *
 *                                                                          *
 *   SPDX-FileCopyrightText: Copyright 2005-2026                            *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
 *   SPDX-License-Identifier: LGPL-3.0-or-later OR MIT                      *
 *                                                                          *
 *   Contact  : info_at_agrum_dot_org                                       *
 *   homepage : http://agrum.gitlab.io                                      *
 *   gitlab   : https://gitlab.com/agrumery/agrum                           *
 *                                                                          *
 ****************************************************************************/
 
#pragma once

 
#include <agrum/base/core/utils_random.h>   // to ease IDE parser
 
namespace gum {
 
  // return a random discrete distribution
  // @param n is the number of modalities for the distribution
  template < GUM_Numeric GUM_SCALAR >
  std::vector< GUM_SCALAR > randomDistribution(Size n) {
    if (n < 2) n = 2;
 
    if (n == std::numeric_limits< Size >::max()) {
      GUM_ERROR(OutOfBounds, "randomDistribution: n is too large (SIZE_MAX would overflow n+1)")
    }
 
    // using sort method for uniformly distributed distributions
    // https://doi.org/10.1016/0377-2217(82)90161-8
    std::vector< GUM_SCALAR > v(n + 1);
    std::vector< GUM_SCALAR > res(n);
    v[0] = (GUM_SCALAR)0.0;
    v[n] = (GUM_SCALAR)1.0;
    for (Idx i = 1; i < n; i++) {
      v[i] = (GUM_SCALAR)randomProba();
    }
    std::sort(v.begin(), v.end());
 
    for (Idx i = 0; i < n; i++) {
      res[i] = v[i + 1] - v[i];
    }
 
    return res;
  }
 
  template < typename GENERATOR >
  Idx randomValue(GENERATOR& generator, const Size max) {
    std::uniform_int_distribution< Idx > uni_int(0, max - 1);
    return uni_int(generator);
  }
 
 
}   // namespace gum