Changeset 524

Timestamp:

Feb 23, 2006, 4:55:33 PM (16 years ago)

Author:

Peter

Message:

fixed bug PolynimialKernelFunction? - can now handle NaNs? with weights

Location:

trunk/lib/classifier

Files:

• PolynomialKernelFunction.cc (modified) (2 diffs)
• PolynomialKernelFunction.h (modified) (1 diff)

trunk/lib/classifier/PolynomialKernelFunction.cc

@@ -6 +6 @@
 #include <c++_tools/gslapi/matrix.h>
 #include <c++_tools/gslapi/vector.h>
+#include <c++_tools/statistics/AveragerPairWeighted.h>
 
 #include <cmath>
@@ -23 +24 @@
                                             const gslapi::vector& w2) const   
 {
-  double scalar = 0;
-  double normalization_factor = 0;
-  for (size_t i=0; i<a1.size(); i++) {
-    scalar += w1(i) * w2(i) * a1(i) * a2(i);
-    normalization_factor += w1(i) * w2(i);
-  }
-// to make it coherent with no weight case
-  normalization_factor /= a1.size(); 
+  statistics::AveragerPairWeighted averager;
+  averager.add(a1,a2,w1,w2);
+
+  // a1.size() term to make it coherent with no weight case
   if(order_>1) 
-    return pow(scalar/normalization_factor,order_);
-  return scalar/normalization_factor;
+    return pow(1+averager.sum_xy()/averager.sum_w()*a1.size(),order_);
+  return averager.sum_xy()/averager.sum_w()*a1.size();
 }
 

trunk/lib/classifier/PolynomialKernelFunction.h

@@ -44 +44 @@
 
     ///
-    ///returning the scalar product of two vectors in feature space using the
-    ///polynomial kernel with weights.
-    ///   
-    double operator()(const gslapi::vector&, const gslapi::vector&, 
-                      const gslapi::vector&, const gslapi::vector&) const;
+    ///returning the scalar product of two vectors in feature space
+    ///using the polynomial kernel with weights. Having all weights
+    ///equal to unity yields the same as non-weighted version.
+    ///
+    /// @return If order is larger than one: \f$ (1+x \cdot y)^{order}
+    /// \f$ \n If order is one (linear): \f$ N\frac{\sum
+    /// w_xw_yxy}{\sum w_xw_y} \f$
+    /// 
+    ///
+    double operator()(const gslapi::vector& x, const gslapi::vector& y, 
+                      const gslapi::vector& wx, const gslapi::vector& wy) const;
     
   private: