PLearn 0.1
VarElementVariable.cc
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00001 // -*- C++ -*-
00002 
00003 // PLearn (A C++ Machine Learning Library)
00004 // Copyright (C) 1998 Pascal Vincent
00005 // Copyright (C) 1999-2002 Pascal Vincent, Yoshua Bengio, Rejean Ducharme and University of Montreal
00006 // Copyright (C) 2001-2002 Nicolas Chapados, Ichiro Takeuchi, Jean-Sebastien Senecal
00007 // Copyright (C) 2002 Xiangdong Wang, Christian Dorion
00008 
00009 // Redistribution and use in source and binary forms, with or without
00010 // modification, are permitted provided that the following conditions are met:
00011 // 
00012 //  1. Redistributions of source code must retain the above copyright
00013 //     notice, this list of conditions and the following disclaimer.
00014 // 
00015 //  2. Redistributions in binary form must reproduce the above copyright
00016 //     notice, this list of conditions and the following disclaimer in the
00017 //     documentation and/or other materials provided with the distribution.
00018 // 
00019 //  3. The name of the authors may not be used to endorse or promote
00020 //     products derived from this software without specific prior written
00021 //     permission.
00022 // 
00023 // THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
00024 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00025 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
00026 // NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00027 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00028 // TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00029 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00030 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00031 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00032 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00033 // 
00034 // This file is part of the PLearn library. For more information on the PLearn
00035 // library, go to the PLearn Web site at www.plearn.org
00036 
00037 
00038 /* *******************************************************      
00039  * $Id: VarElementVariable.cc 8851 2008-04-21 20:53:25Z tihocan $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "VarElementVariable.h"
00044 #include "ElementAtPositionVariable.h"
00045 
00046 namespace PLearn {
00047 using namespace std;
00048 
00049 
00052 PLEARN_IMPLEMENT_OBJECT(
00053     VarElementVariable,
00054     "Variable that is the element of input1 indexed by input2.",
00055     "If input2 has 2 elements, it is interpreted as a (i,j) pair of indices\n"
00056     "in the matrix view of input1.\n"
00057     "If input2 is scalar, it is interpreted as the index in the vector view\n"
00058     "of input1."
00059 );
00060 
00062 // VarElementVariable //
00064 VarElementVariable::VarElementVariable(Variable* input1, Variable* input2,
00065                                        bool call_build_):
00066     inherited(input1, input2, 1, 1, call_build_)
00067 {
00068     if (call_build_)
00069         build_();
00070 }
00071 
00073 // build //
00075 void VarElementVariable::build()
00076 {
00077     inherited::build();
00078     build_();
00079 }
00080 
00082 // build_ //
00084 void VarElementVariable::build_()
00085 {
00086     if (input2 && input2->nelems() > 2)
00087         PLERROR("IN VarElementVariable(Variable* input1, Variable* input2) input2 must have 1 (a k position index) or 2 elements (an i,j position index)");
00088 }
00089 
00090 void VarElementVariable::recomputeSize(int& l, int& w) const
00091 { l=1; w=1; }
00092 
00093 void VarElementVariable::fprop()
00094 {
00095     if(input2->isScalar()) // scalar position index k
00096     {
00097         int k = int(input2->valuedata[0]);
00098 #ifdef BOUNDCHECK
00099         if (k >= input1->length() && k>= input1->width()) // we want to allow acces both to row vectors and column vectors.
00100             PLERROR("VarElementVariable::fprop() - k = %d is out of range (size is %d)", k, input1->length());
00101 #endif
00102         valuedata[0] = input1->valuedata[k];
00103     }
00104     else // (i,j) position index
00105     {
00106         int i = int(input2->valuedata[0]);
00107         int j = int(input2->valuedata[1]);
00108 #ifdef BOUNDCHECK
00109         if ((i * input1->width() + j) >= input1->width() * input1->length())
00110             PLERROR("VarElementVariable::fprop() - (%d, %d) out of range"
00111                     "(size is %d)", i, j, input1->length() * input1->width());
00112 #endif
00113         valuedata[0] = input1->valuedata[i*input1->width()+j];
00114     }
00115 }
00116 
00117 
00118 void VarElementVariable::bprop()
00119 {
00120     if(input2->isScalar()) // scalar position index k
00121     {
00122         int k = int(input2->valuedata[0]);
00123         input1->gradientdata[k] += gradientdata[0];
00124     }
00125     else // (i,j) position index
00126     {
00127         int i = int(input2->valuedata[0]);
00128         int j = int(input2->valuedata[1]);
00129         input1->gradientdata[i*input1->width()+j] += gradientdata[0];
00130     }
00131 }
00132 
00133 
00134 void VarElementVariable::symbolicBprop()
00135 {
00136     input1->accg(new ElementAtPositionVariable(g,input2,input1->length(),input1->width()));
00137 }
00138 
00139 
00140 void VarElementVariable::rfprop()
00141 {
00142     if (rValue.length()==0) resizeRValue();
00143     if(input2->isScalar()) // scalar position index k
00144     {
00145         int k = int(input2->valuedata[0]);
00146         rvaluedata[0] = input1->rvaluedata[k];
00147     }
00148     else // (i,j) position index
00149     {
00150         int i = int(input2->valuedata[0]);
00151         int j = int(input2->valuedata[1]);
00152         rvaluedata[0] = input1->rvaluedata[i*input1->width()+j];
00153     }
00154 }
00155 
00156 
00157 
00158 } // end of namespace PLearn
00159 
00160 
00161 /*
00162   Local Variables:
00163   mode:c++
00164   c-basic-offset:4
00165   c-file-style:"stroustrup"
00166   c-file-offsets:((innamespace . 0)(inline-open . 0))
00167   indent-tabs-mode:nil
00168   fill-column:79
00169   End:
00170 */
00171 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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