n_max.hh

// Copyright (C) 2009 EPITA Research and Development Laboratory (LRDE)
//
// This file is part of Olena.
//
// Olena 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, version 2 of the License.
//
// Olena 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 Olena.  If not, see <http://www.gnu.org/licenses/>.
//
// As a special exception, you may use this file as part of a free
// software project without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to produce
// an executable, this file does not by itself cause the resulting
// executable to be covered by the GNU General Public License.  This
// exception does not however invalidate any other reasons why the
// executable file might be covered by the GNU General Public License.

#ifndef MLN_LABELING_N_MAX_HH
# define MLN_LABELING_N_MAX_HH

# include <mln/core/concept/image.hh>
# include <mln/accu/math/count.hh>
# include <mln/labeling/compute.hh>
# include <mln/util/array.hh>



namespace mln
{

  namespace labeling
  {

    template <typename L, typename V>
    util::array<L>
    n_max(const util::array<V>& in_arr, unsigned n);


    template <typename L>
    util::array<mln_value(L)>
    n_max(const Image<L>& lbl, const mln_value(L)& nlabels, unsigned n);


# ifndef MLN_INCLUDE_ONLY

    template <typename L, typename V>
    util::array<L>
    n_max(const util::array<V>& in_arr, unsigned n)
    {
      trace::entering("mln::labeling::n_max");

      mln_precondition(n < in_arr.nelements());

      util::array<L> output(n + 1, 0);
      for (unsigned i = 0; i < n + 1; ++i)
        output[i] = i;
      int swap = 0;
      for (int j = n - 1; j > 0; --j)
      {
        if (in_arr[output[j]] < in_arr[output[j + 1]])
        {
          swap = output[j];
          output[j] = output[j + 1];
          output[j + 1] = swap;
        }
      }

      for (unsigned i = n; i < in_arr.nelements(); ++i)
      {
        if (in_arr[i] > in_arr[output[n]])
        {
          output[n] = i;
          for (unsigned j = n - 1; j > 0 && in_arr[output[j]] < in_arr[output[j + 1]]; --j)
          {
            swap = output[j];
            output[j] = output[j + 1];
            output[j + 1] = swap;
          }
        }
      }

      trace::exiting("mln::labeling::n_max");
      return output;
    }


    template <typename L>
    util::array<mln_value(L)>
    n_max(const Image<L>& lbl, const mln_value(L)& nlabels, unsigned n)
    {
      mln_precondition(exact(lbl).is_valid());

      typedef accu::math::count<mln_site(L)> accu_t;
      accu_t accu;

      util::array<mln_result(accu_t)>
        counts = labeling::compute(accu, lbl, nlabels);

      return n_max<mln_value(L)>(counts, n);
    }


# endif // !MLN_INCLUDE_ONLY

  } // end of namespace mln::labeling

} // end of namespace mln

#endif // ! MLN_LABELING_N_MAX_HH