PLearn 0.1
ConfRatedAdaboostCostVariable.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 // Copyright (C) 2003 Olivier Delalleau
00009 
00010 // Redistribution and use in source and binary forms, with or without
00011 // modification, are permitted provided that the following conditions are met:
00012 // 
00013 //  1. Redistributions of source code must retain the above copyright
00014 //     notice, this list of conditions and the following disclaimer.
00015 // 
00016 //  2. Redistributions in binary form must reproduce the above copyright
00017 //     notice, this list of conditions and the following disclaimer in the
00018 //     documentation and/or other materials provided with the distribution.
00019 // 
00020 //  3. The name of the authors may not be used to endorse or promote
00021 //     products derived from this software without specific prior written
00022 //     permission.
00023 // 
00024 // THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
00025 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00026 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
00027 // NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00028 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00029 // TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00030 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00031 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00032 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00033 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00034 // 
00035 // This file is part of the PLearn library. For more information on the PLearn
00036 // library, go to the PLearn Web site at www.plearn.org
00037 
00038 
00039 /* *******************************************************      
00040  * $Id: ConfRatedAdaboostCostVariable.cc 6827 2007-04-03 23:08:36Z larocheh $
00041  * This file is part of the PLearn library.
00042  ******************************************************* */
00043 
00044 #include "ConfRatedAdaboostCostVariable.h"
00045 
00046 namespace PLearn {
00047 using namespace std;
00048 
00051 PLEARN_IMPLEMENT_OBJECT(
00052     ConfRatedAdaboostCostVariable,
00053     "Cost used for Confidence-rated Adaboost ",
00054     "See \"Improved Boosting Algorithms Using Confidence-rated Predictions\" by\n"
00055     "Schapire and Singer.");
00056 
00058 // ConfRatedAdaboostCostVariable //
00060 ConfRatedAdaboostCostVariable::ConfRatedAdaboostCostVariable(Variable* output, Variable* target, Variable* alpha)
00061     : inherited(VarArray(output,target) & Var(alpha),output->size(),1)
00062 {
00063     build_();
00064 }
00065 
00066 void
00067 ConfRatedAdaboostCostVariable::build()
00068 {
00069     inherited::build();
00070     build_();
00071 }
00072 
00073 void
00074 ConfRatedAdaboostCostVariable::build_()
00075 {
00076 
00077     if (varray[1] && varray[0] && varray[1]->size() != varray[0]->size())
00078         PLERROR("In ConfRatedAdaboostCostVariable: target and output should have same size");
00079 
00080     if (varray[2] && varray[2]->size() != 1)
00081         PLERROR("In ConfRatedAdaboostCostVariable: target must be a single real");
00082 }
00083 
00084 void
00085 ConfRatedAdaboostCostVariable::declareOptions(OptionList &ol)
00086 {
00087 }
00088 
00090 // recomputeSize //
00092 void ConfRatedAdaboostCostVariable::recomputeSize(int& l, int& w) const
00093 { l=varray[0]->size(), w=1; }
00094 
00096 // fprop //
00098 void ConfRatedAdaboostCostVariable::fprop()
00099 {
00100   
00101     int signed_target;
00102     for(int i=0; i<length(); i++)
00103     {
00104         signed_target = 2*int(varray[1]->valuedata[i])-1;  
00105         valuedata[i] = exp(-1*varray[2]->valuedata[0]*signed_target*(2*varray[0]->valuedata[i]-1));
00106     }
00107 }
00108 
00110 // bprop //
00112 void ConfRatedAdaboostCostVariable::bprop()
00113 {
00114     for(int i=0; i<length(); i++)
00115     {
00116         varray[0]->gradientdata[i] += -2*gradientdata[i]*valuedata[i]*varray[2]->valuedata[0]*(2*int(varray[1]->valuedata[i])-1);  
00117         varray[2]->gradientdata[0] += -gradientdata[i]*valuedata[i]*(2*varray[0]->valuedata[i]-1)*(2*int(varray[1]->valuedata[i])-1);  
00118     }
00119 }
00120 
00121 void ConfRatedAdaboostCostVariable::symbolicBprop()
00122 {
00123     PLERROR("ConfRatedAdaboostCostVariable::symbolicBprop() not implemented");
00124 }
00125 
00126 } // end of namespace PLearn
00127 
00128 
00129 /*
00130   Local Variables:
00131   mode:c++
00132   c-basic-offset:4
00133   c-file-style:"stroustrup"
00134   c-file-offsets:((innamespace . 0)(inline-open . 0))
00135   indent-tabs-mode:nil
00136   fill-column:79
00137   End:
00138 */
00139 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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