tensor_sort_d.cc

// -*- mode: c++; fill-column: 80; c-basic-offset: 2; indent-tabs-mode: nil -*-
/*
    Copyright (c) 2010 Juan Jose Garcia Ripoll

    Tensor is free software; you can redistribute it and/or modify it
    under the terms of the GNU Library General Public License as published
    by the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program 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 Library General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <algorithm>
#include <functional>
#include <tensor/tensor.h>

namespace tensor {

  const RTensor
  sort(const RTensor &v, bool reverse)
  {
    RTensor output(v);
    if (reverse) {
      std::sort(output.begin(), output.end(), std::greater<double>());
    } else {
      std::sort(output.begin(), output.end(), std::less<double>());
    }
    return output;
  }

  template<typename elt_t>
  struct Compare {
    const elt_t *p;

    Compare(const elt_t *newp) : p(newp) {};
    int operator()(size_t i1, size_t i2) {
      return p[i1] < p [i2];
    }
  };

  template<typename elt_t>
  struct CompareInv {
    const elt_t *p;

    CompareInv(const elt_t *newp) : p(newp) {};
    int operator()(size_t i1, size_t i2) {
      return p[i1] > p[i2];
    }
  };

  const Indices
  sort_indices(const RTensor &v, bool reverse)
  {
    if (v.size()) {
      Indices output = iota(0,v.size()-1);
      if (reverse) {
        CompareInv<double> c(v.begin());
        std::sort(output.begin(), output.end(), c);
      } else {
        Compare<double> c(v.begin());
        std::sort(output.begin(), output.end(), c);
      }
      return output;
    } else {
      return Indices();
    }
  }

}