Sort.cpp

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/* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
   Copyright (c) 2013 The plumed team
   (see the PEOPLE file at the root of the distribution for a list of names)

   See http://www.plumed-code.org for more information.

   This file is part of plumed, version 2.0.

   plumed is free software: you can redistribute it and/or modify
   it under the terms of 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.

   plumed 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 Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with plumed.  If not, see <http://www.gnu.org/licenses/>.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
#include "ActionRegister.h"
#include "Function.h"

#include <cmath>
#include <algorithm>
#include <utility>

using namespace std;

namespace PLMD{
namespace function{

//+PLUMEDOC FUNCTION SORT
/*
This function can be used to sort colvars according to their magnitudes.

\par Description of components

This function sorts its arguments according to their magnitudes. The largest argument will be 
labelled <em>label</em>.1, the second largest will be labelled <em>label</em>.2 and so on.  

\par Examples
The following input tells plumed to print the distance of the closest and of
the farthest atoms to atom 1, chosen among atoms from 2 to 5
\verbatim
d12:  DISTANCE ATOMS=1,2
d13:  DISTANCE ATOMS=1,3
d14:  DISTANCE ATOMS=1,4
d15:  DISTANCE ATOMS=1,5
sort: SORT ARG=d12,d13,d14,d15
PRINT ARG=sort.1,sort.4
\endverbatim
(See also \ref PRINT and \ref DISTANCE).

*/
//+ENDPLUMEDOC


class Sort :
  public Function
{
public:
  Sort(const ActionOptions&);
  void calculate();
  static void registerKeywords(Keywords& keys);
};


PLUMED_REGISTER_ACTION(Sort,"SORT")

void Sort::registerKeywords(Keywords& keys){
  Function::registerKeywords(keys);
  keys.use("ARG");
  ActionWithValue::useCustomisableComponents(keys);
}

Sort::Sort(const ActionOptions&ao):
Action(ao),
Function(ao)
{
  for(unsigned i=0;i<getNumberOfArguments();++i){
    string s;
    Tools::convert(i+1,s);
    if(getPntrToArgument(i)->isPeriodic())
      error("Cannot sort periodic values (check argument "+s+")");
    addComponentWithDerivatives(s); 
    getPntrToComponent(i)->setNotPeriodic();
  }
  checkRead();

}

void Sort::calculate(){
  vector<pair<double,int> > vals(getNumberOfArguments());
  for(unsigned i=0;i<getNumberOfArguments();++i){
    vals[i].first=getArgument(i);
// In this manner I remember from which argument the component depends:
    vals[i].second=i;
  }
// STL sort sorts based on first element (value) then second (index)
  sort(vals.begin(),vals.end());
  for(unsigned i=0;i<getNumberOfComponents();++i){
    Value* v=getPntrToComponent(i);
    v->set(vals[i].first);
    setDerivative(v,vals[i].second,1.0);
  }
}

}
}