Changeset 37 for trunk

Timestamp:

Feb 13, 2004, 4:46:31 PM (19 years ago)

Author:

Peter

Message:

SVM.get_output added

Location:

trunk/src

Files:

• SVM.cc (modified) (4 diffs)
• SVM.h (modified) (4 diffs)
• vector.cc (modified) (1 diff)

trunk/src/SVM.cc

@@ -20 +20 @@
                  kernel_(kernel),
                  target_(target),
-                 alpha_(target.size(),true,true)
+                 alpha_(target.size(),true,true),
+                 bias_(0)
+  
 {
 }
@@ -38 +40 @@
   // Stop criteria  
   bool stop_condition = false;
-  while(count<100000 && !stop_condition)
+  while(!stop_condition)
     {
      count++;  
@@ -90 +92 @@
      alpha_[index2]=alpha_new;
      stop_condition = stop( target_, kernel_, alpha_);
+     if (count>10000000){
+      cerr << "SVM): " << "more than 10,000,000 epochs reached" << endl;
+       exit(1);
+     }
     }
+
+  // Calculating the bias
+  double min_output_positive = 10000;
+  double max_output_negative = -10000;
+  thep_gsl_api::vector output_unbiased = kernel_ * alpha_.mul_elements(target_);
+  for (u_int i=0; i<target_.size(); i++){
+   if (target_[i]==1){
+     if (output_unbiased[i] < min_output_positive)
+       min_output_positive = output_unbiased[i];
+   }
+   else if( output_unbiased[i] > max_output_negative )
+     max_output_negative = output_unbiased[i];
   
+  }
+  cout << max_output_negative << endl;
+  cout << min_output_positive << endl;
+  
+  bias_ = ( -min_output_positive - max_output_negative )/2;
+  cout << "bias:" << bias_ << endl;
+
   trained_= true;
 }
@@ -101 +126 @@
   double min_output_positive = 10000;
   double max_output_negative = -10000;
-  double epsilon = 0.001; // used twice, should perhaps be two different values
+  double epsilon = 0.000001; // used twice, should perhaps be two different values
   thep_gsl_api::vector output_unbiased = kernel_ * alpha_.mul_elements(target_);
   for (u_int i=0; i<target_.size(); i++){

trunk/src/SVM.h

@@ -8 +8 @@
 #include "vector.h"
 #include "matrix.h"
+
 
 // Standard C++ includes
@@ -34 +35 @@
     */
     inline thep_gsl_api::vector get_alpha() const;
+
+    /**
+       Function will return the output from SVM
+    */
+    inline thep_gsl_api::vector get_output() const;
+
    
       
@@ -41 +48 @@
     thep_gsl_api::vector target_;
     thep_gsl_api::vector alpha_;
+    double bias_;
 
     /**
-       Private function that determines when to stop the training
+       Private function that determines when to stop the training.
+       The test is done in two steps. First, we check that the
+       functional margin is at least 2 - epsilon. Second, we check
+       that the gap between the primal and the dual object is less
+       than epsilon.
+
     */
     bool SVM::stop(const thep_gsl_api::vector& target_,
@@ -55 +68 @@
     return alpha_;
   }
+
+  thep_gsl_api::vector SVM::get_output() const  
+  {
+    thep_gsl_api::vector bias(target_.size(), false, false);
+    bias.set_all(bias_);
+    return kernel_ * alpha_.mul_elements(target_) + bias;
+    
+  }
 }; // namespace thep_c++_tools
 

trunk/src/vector.cc

@@ -247 +247 @@
 {
   double sum = 0;
-  for (int i=0; i<size(); i++)
+  for (u_int i=0; i<size(); i++)
    sum += gsl_vector_get( v_, i );
   return( sum );