PLearn 0.1
ProbVector.cc
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00001 // -*- C++ -*-
00002 
00003 // PLearn (A C++ Machine Learning Library)
00004 // Copyright (C) 2003 Christopher Kermorvant
00005 //
00006 
00007 // Redistribution and use in source and binary forms, with or without
00008 // modification, are permitted provided that the following conditions are met:
00009 // 
00010 //  1. Redistributions of source code must retain the above copyright
00011 //     notice, this list of conditions and the following disclaimer.
00012 // 
00013 //  2. Redistributions in binary form must reproduce the above copyright
00014 //     notice, this list of conditions and the following disclaimer in the
00015 //     documentation and/or other materials provided with the distribution.
00016 // 
00017 //  3. The name of the authors may not be used to endorse or promote
00018 //     products derived from this software without specific prior written
00019 //     permission.
00020 // 
00021 // THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
00022 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00023 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
00024 // NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00025 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00026 // TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00027 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00028 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00029 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00030 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00031 // 
00032 // This file is part of the PLearn library. For more information on the PLearn
00033 // library, go to the PLearn Web site at www.plearn.org
00034 
00037 #include "ProbVector.h"
00038 
00039 namespace PLearn {
00040 
00041 void ProbVector::smoothNormalize(string name,real discounting_value)
00042 {
00043     // smooth by discounting  and Normalize
00044 
00045 #ifdef DEBUG  
00046     cout << "Smoothing "<< name;
00047 #endif
00048     bool err_smooth_flag=false;
00049     int f;
00050     int size =  length_;
00051     real *v = data();
00052     real word_seen=0;
00053     real sum_discounted=0.0;
00054     real sum_v = 0;
00055 
00056     for(f=0;f<size;f++){
00057         if (v[f]>discounting_value){
00058             sum_v+=v[f];
00059             v[f]-=discounting_value;
00060             sum_discounted +=discounting_value;
00061             word_seen++;
00062             continue;
00063         }
00064         // in the case of non integer counts (typically during E.M. algo)
00065         if (v[f]>0 && v[f]<discounting_value){
00066             sum_v+=v[f];
00067             err_smooth_flag=true;
00068         }
00069     }
00070 #ifdef DEBUG  
00071     cout << ": discounted " << sum_discounted << " from " << word_seen << " seen events summing " <<sum_v ;
00072 #endif
00073     // distribute discounted mass
00074     real unseen_prob=sum_discounted/(sum_v*size);
00075     word_seen=0;
00076     for(f=0;f<size;f++){
00077         // Distribute on both seen and unseen events
00078         //if (v[f]<=discounting_value){
00079         word_seen++;
00080         v[f]/=sum_v;
00081         v[f]+= unseen_prob;
00082         // }else{
00083         //       v[f]/=sum_v;
00084         //     }
00085     }
00086 #ifdef DEBUG  
00087     cout << " redistribute " << unseen_prob << " to "<< word_seen << " unseen events" <<endl;
00088 #endif
00089     if(err_smooth_flag)PLWARNING("minimal value < discounted value in Backoff  Smoothing smoothNormalize a probVector");
00090 }
00091 
00092 void ProbVector::normalize()
00093 {
00094     // Normalize the vector (sum = 1)
00095     int f;
00096     int size =  length_;
00097     real *v = data();
00098     real sum_v = 0;
00099 
00100     for(f=0;f<size;f++){
00101         sum_v+=v[f];
00102     }
00103     for(f=0;f<size;f++){
00104         v[f]/=sum_v;
00105     }
00106 }
00107 
00108 }
00109 
00110 
00111 /*
00112   Local Variables:
00113   mode:c++
00114   c-basic-offset:4
00115   c-file-style:"stroustrup"
00116   c-file-offsets:((innamespace . 0)(inline-open . 0))
00117   indent-tabs-mode:nil
00118   fill-column:79
00119   End:
00120 */
00121 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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