PLearn 0.1
ElementAtPositionVariable.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: ElementAtPositionVariable.cc 3994 2005-08-25 13:35:03Z chapados $
00040  * This file is part of the PLearn library.
00041  ******************************************************* */
00042 
00043 #include "ElementAtPositionVariable.h"
00044 #include "VarElementVariable.h"
00045 
00046 namespace PLearn {
00047 using namespace std;
00048 
00049 
00052 PLEARN_IMPLEMENT_OBJECT(
00053     ElementAtPositionVariable,
00054     "Indicator-like variable",
00055     "A variable of size length() x width(), filled with zeros except for the "
00056     "single element indexed by input2 =(i,j) or input2 = (k).");
00057   
00058 ElementAtPositionVariable::ElementAtPositionVariable()
00059     : length_(0), width_(0)
00060 { }
00061 
00062   
00063 ElementAtPositionVariable::ElementAtPositionVariable(Variable* input1, Variable* input2, int the_length, int the_width)
00064     : inherited(input1, input2, the_length, the_width), length_(the_length), width_(the_width)
00065 {
00066     build_();
00067 }
00068 
00069 void
00070 ElementAtPositionVariable::build()
00071 {
00072     inherited::build();
00073     build_();
00074 }
00075 
00076 void
00077 ElementAtPositionVariable::build_()
00078 {
00079     if (input1 && !input1->isScalar())
00080         PLERROR("In ElementAtPositionVariable: element must be a scalar var");
00081     if (input2 && input2->nelems()>2)
00082         PLERROR("In ElementAtPositionVariable: position must have 1 or 2 elements");
00083 }
00084 
00085 void
00086 ElementAtPositionVariable::declareOptions(OptionList &ol)
00087 {
00088     declareOption(ol, "length_", &ElementAtPositionVariable::length_, OptionBase::buildoption, "");
00089     declareOption(ol, "width_", &ElementAtPositionVariable::width_, OptionBase::buildoption, "");
00090     inherited::declareOptions(ol);
00091 }
00092 
00093 void ElementAtPositionVariable::recomputeSize(int& l, int& w) const
00094 { l=length_; w=width_; }
00095 
00096 void ElementAtPositionVariable::fprop()
00097 {
00098     value.clear();
00099     if (input2->isScalar()) // input2 is a scalar (interpreted as a k)
00100     {
00101         int k = (int)input2->valuedata[0];
00102         valuedata[k] = input1->valuedata[0];
00103     }
00104     else // input2 has 2 elements (interpreted as (i,j) coordinates)
00105     {
00106         int i = (int)input2->valuedata[0];
00107         int j = (int)input2->valuedata[1];
00108         valuedata[i*width()+j] = input1->valuedata[0];
00109     }
00110 }
00111 
00112 
00113 void ElementAtPositionVariable::bprop()
00114 {
00115     if (input2->isScalar()) // input2 is a scalar (interpreted as a k)
00116     {
00117         int k = (int)input2->valuedata[0];
00118         input1->gradientdata[0] += gradientdata[k];
00119     }
00120     else // input2 has 2 elements (interpreted as (i,j) coordinates)
00121     {
00122         int i = (int)input2->valuedata[0];
00123         int j = (int)input2->valuedata[1];
00124         input1->gradientdata[0] += gradientdata[i*width()+j];
00125     }  
00126 }
00127 
00128 
00129 void ElementAtPositionVariable::symbolicBprop()
00130 {
00131     input1->accg(new VarElementVariable(g,input2));
00132 }
00133 
00134 
00135 
00136 void ElementAtPositionVariable::rfprop()
00137 {
00138     if (rValue.length()==0) resizeRValue();
00139     rValue.clear();
00140     if (input2->isScalar()) // input2 is a scalar (interpreted as a k)
00141     {
00142         int k = (int)input2->valuedata[0];
00143         rvaluedata[k] = input1->rvaluedata[0];
00144     }
00145     else // input2 has 2 elements (interpreted as (i,j) coordinates)
00146     {
00147         int i = (int)input2->valuedata[0];
00148         int j = (int)input2->valuedata[1];
00149         rvaluedata[i*width()+j] = input1->rvaluedata[0];
00150     }
00151 }
00152 
00153 
00154 
00155 } // end of namespace PLearn
00156 
00157 
00158 /*
00159   Local Variables:
00160   mode:c++
00161   c-basic-offset:4
00162   c-file-style:"stroustrup"
00163   c-file-offsets:((innamespace . 0)(inline-open . 0))
00164   indent-tabs-mode:nil
00165   fill-column:79
00166   End:
00167 */
00168 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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