VarArrayElementVariable.cc

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// -*- C++ -*-

// PLearn (A C++ Machine Learning Library)
// Copyright (C) 1998 Pascal Vincent
// Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio, Rejean Ducharme and University of Montreal
// Copyright (C) 2001-2002 Nicolas Chapados, Ichiro Takeuchi, Jean-Sebastien Senecal
// Copyright (C) 2002 Xiangdong Wang, Christian Dorion

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// modification, are permitted provided that the following conditions are met:
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//  1. Redistributions of source code must retain the above copyright
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/* *******************************************************      
   * $Id: VarArrayElementVariable.cc,v 1.6 2004/05/04 21:15:53 nova77 Exp $
   * This file is part of the PLearn library.
   ******************************************************* */

#include "VarArrayElementVariable.h"

namespace PLearn {
using namespace std;


/* selects one element of a VarArray according to a Var index */

PLEARN_IMPLEMENT_OBJECT(VarArrayElementVariable,
                        "Selects one element of a VarArray according to a Var index */",
                        "NO HELP");

VarArrayElementVariable::
VarArrayElementVariable(VarArray& input1, const Var& input2)
  : inherited(input1 & (VarArray)input2, input1[0]->length(), input1[0]->width())
{
    build_();
}

void
VarArrayElementVariable::build()
{
    inherited::build();
    build_();
}

void
VarArrayElementVariable::build_()
{
    if (varray.size() >= 2) {// && varray[0] && varray[1] && varray[1].size()) {
        int l = varray[0]->length();
        int w = varray[0]->width();
        for (int i = 1; i < varray.size() - 1; i++)
            if (varray[i]->length() != l || varray[i]->width() != w)
                PLERROR("VarArrayElementVairables expect all the elements of input1 array to have the same size");
        if (!varray[varray.size() - 1]->isScalar())
            PLERROR("VarArrayElementVariable expect an index Var (input2) of length 1");
    }
}


void VarArrayElementVariable::recomputeSize(int& l, int& w) const
{
    if (varray.size()) {
        l = varray[0]->length();
        w = varray[0]->width();
    } else
        l = w = 0;
}

void VarArrayElementVariable::fprop()
{
  int index = (int)(varray.last()->valuedata[0]);
#ifdef BOUNDCHECK
  if (index<0 || index>=varray.size()-1)
    PLERROR("VarArrayElementVariable::fprop, out of bound access of array(%d) at %d",
          varray.size()-1,index);
#endif
  for (int i=0;i<nelems();i++)
    valuedata[i] = varray[index]->valuedata[i];
}


void VarArrayElementVariable::bprop()
{
  int index = (int)(varray.last()->valuedata[0]);
  for (int i=0;i<nelems();i++)
    varray[index]->gradientdata[i] += gradientdata[i];
}


void VarArrayElementVariable::symbolicBprop()
{
  int index = (int)(varray.last()->valuedata[0]);
  varray[index]->accg(g);
}



} // end of namespace PLearn

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