PLearn 0.1
ColumnIndexVariable.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: ColumnIndexVariable.cc 9184 2008-06-26 21:07:47Z chrish $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "ColumnIndexVariable.h"
00044 #include "IndexAtPositionVariable.h"
00045 namespace PLearn {
00046 using namespace std;
00047 
00048 
00049 
00052 PLEARN_IMPLEMENT_OBJECT(
00053     ColumnIndexVariable,
00054     "Return a row vector with the elements indexed in each column.",
00055     "The first input is a matrix of size NxM.\n"
00056     "The second input is a vector of size M, with elements in {0, ..., N-1}.\n"
00057     "The result is a row vector of size M, where the i-th element is equal\n"
00058     "to input1(input2[i], i)."
00059 );
00060 
00061 ColumnIndexVariable::ColumnIndexVariable(Variable *input1, Variable *input2)
00062     : inherited(input1, input2, 1, input1->width())
00063 {
00064     build_();
00065 }
00066 
00068 // build //
00070 void ColumnIndexVariable::build()
00071 {
00072     inherited::build();
00073     build_();
00074 }
00075 
00077 // build_ //
00079 void ColumnIndexVariable::build_()
00080 {
00081     if (input2 && !input2->isVec())
00082         PLERROR("In ColumnIndexVariable::build_ - input2 must be a vector "
00083                 "variable representing the indices of input1");
00084     if (input1 && input2 && input1->width() != input2->size())
00085         PLERROR("In ColumnIndexVariable::build_ - input1's width (%d) "
00086                 "should be equal to input2's size (%d)",
00087                 input1->width(), input2->size());
00088 }
00089 
00091 // recomputeSize //
00093 void ColumnIndexVariable::recomputeSize(int& l, int& w) const
00094 {
00095     l = 1;
00096     if (input1)
00097         w = input1->width();
00098     else
00099         w = 0;
00100 }
00101 
00103 // fprop //
00105 void ColumnIndexVariable::fprop()
00106 {
00107     for (int i=0; i<input2->size(); i++)
00108     {
00109         int num = (int)input2->valuedata[i];
00110         valuedata[i] = input1->valuedata[num*input1->width()+i];
00111     }
00112 }
00113 
00114 
00115 void ColumnIndexVariable::bprop()
00116 {
00117     for (int i=0; i<input2->size(); i++)
00118     {
00119         int num = (int) input2->valuedata[i];
00120         input1->gradientdata[num*input1->width()+i] += gradientdata[i];
00121     }
00122 }
00123 
00124 
00125 void ColumnIndexVariable::symbolicBprop()
00126 {
00127     input1->accg(new IndexAtPositionVariable(g,input2,input1->length(),input1->width()));
00128 }
00129 
00130 
00131 
00132 } // end of namespace PLearn
00133 
00134 
00135 /*
00136   Local Variables:
00137   mode:c++
00138   c-basic-offset:4
00139   c-file-style:"stroustrup"
00140   c-file-offsets:((innamespace . 0)(inline-open . 0))
00141   indent-tabs-mode:nil
00142   fill-column:79
00143   End:
00144 */
00145 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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