Changeset 1521 for trunk/yat/normalizer/Zscore.h

Timestamp:

Sep 21, 2008, 7:54:19 PM (15 years ago)

Author:

Peter

Message:

Adding a Zscore normalizer

File:

• trunk/yat/normalizer/Zscore.h (copied) (copied from trunk/yat/normalizer/Centralizer.h) (4 diffs)

trunk/yat/normalizer/Zscore.h

@@ -1 @@
-#ifndef _theplu_yat_normalizer_centralizer_
-#define _theplu_yat_normalizer_centralizer_
+#ifndef _theplu_yat_normalizer_z_score_
+#define _theplu_yat_normalizer_z_score_
 
 /*
@@ -21 +21 @@
 */
 
-#include "yat/statistics/Average.h"
-
-#include <algorithm>
-#include <functional>
+#include "yat/statistics/Averager.h"
 
 namespace theplu {
@@ -31 +28 @@
 
   /**
-     \brief Centralize a range
+     \brief Zero mean and unity variance
 
-     The center is calculated and then that value is subtracted from
-     each element. By default the center is defined as the arithmetic
-     mean, but this can be changed by providing a suitable
-     UnaryFunction.
+     Create a range that has zero mean and unity variance
 
      \since New in yat 0.5
    */
-  template<class UnaryFunction = statistics::Average>
-  class Centralizer
+  class Zscore
   {
   public:
     /**
-       \brief default constructor
-
-       Creates a UnaryFunction using default constructor.
-     */
-    Centralizer(void){}
-
-    /**
-       \param uf unary function defining the center.
-     */
-    Centralizer(const UnaryFunction& uf)
-      : func_(uf) {}
-
-    /**
-       Calculates the center \a c of the range [first, last) using
-       UnaryFunction. This value, \a c, is then subtracted from each
-       element in the range [first, last) and assigned to the
-       corresponding element in range [result, result + (last-first) ).
+       The element in range [result, result + (last-first)) is
+       calculated as result[i] = (first[i] - m) / std where m and std
+       are the mean and standard deviation, respectively, of the range
+       [first, last).
 
        It is possible to centralize a range "in place"; it is
@@ -73 +53 @@
                               OutputIterator result) const
     {
-      return std::transform(first, last, 
-                            result, std::bind2nd(std::minus<double>(),
-                                                 func_(first, last)));
+      statistics::Averager a;
+      add(a, first, last);
+      double m = a.mean();
+      double std = a.std();
+      while (first!=last) {
+        *result = (*first - m) / std;
+        ++first;
+        ++result;
+      }
+      return result;
     }
 
-  private:
-    UnaryFunction func_;
   };