utils_random_tpl.h

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 *   This file is part of the aGrUM/pyAgrum library.                        *
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 *   Copyright (c) 2005-2025 by                                             *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
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 *   SPDX-FileCopyrightText: Copyright 2005-2025                            *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
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 *   homepage : http://agrum.gitlab.io                                      *
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#pragma once

 
namespace gum {
 
  // return a random discrete distribution
  // @param n is the number of modalities for the distribution
  template < typename GUM_SCALAR >
  std::vector< GUM_SCALAR > randomDistribution(Size n) {
    if (n < 2) n = 2;
 
    // 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 >
  INLINE Idx randomValue(GENERATOR& generator, const Size max) {
    std::uniform_int_distribution< Idx > uni_int(0, max - 1);
    return uni_int(generator);
  }
 
 
}   // namespace gum