[Positioner] Measurement: rename variance variables

We compute only the variance for the milliwatt values, so the
variance-related variables are renamed with the _mw suffix.

owlps-positioner/src/measurement.cc

@@ -108,15 +108,15 @@ void Measurement::merge(const Measurement &source)
 /**
  * - #ap is not deleted, only initialised to NULL.
  * - #ss_list is cleared.
- * - #average_dbm, #average_mw and #variance are reset to 0.
+ * - #average_dbm, #average_mw and #variance_mw are reset to 0.
  */
 void Measurement::clear()
 {
   ss_list.clear() ;
   average_dbm = 0 ;
   average_mw = 0 ;
-  variance = 0 ;
-  variance_m2 = 0 ;
+  variance_mw = 0 ;
+  variance_mw_m2 = 0 ;
   ap = NULL ;
 }
 
@@ -137,12 +137,12 @@ float Measurement::similarity(const Measurement &source) const
     return ss_square_distance(source) ;
 
   if (algorithm == "interval")
-    return 1 / nb_in_interval(source, get_std_deviation()) ;
+    return 1 / nb_in_interval(source, get_std_deviation_mw()) ;
   /* Note: this score ranges from 0 (excluded) to 1 (obviously). */
 
   if (algorithm == "interval2")
     {
-      float std_dev = get_std_deviation() ;
+      float std_dev = get_std_deviation_mw() ;
       float interval1 = nb_in_interval(source, 0.674 * std_dev) ;
       float interval2 = nb_in_interval(source, std_dev) ;
       /* Explanation: with a normal distribution, we normally have:
@@ -184,8 +184,8 @@ void Measurement::recalculate_average()
 {
   average_dbm = 0 ;
   average_mw = 0 ;
-  variance = 0 ;
-  variance_m2 = 0 ;
+  variance_mw = 0 ;
+  variance_mw_m2 = 0 ;
 
   for (map<pkt_id_t, ss_t>::const_iterator
        i = ss_list.begin() ; i != ss_list.end() ; ++i)
@@ -204,9 +204,9 @@ void Measurement::update_average(ss_t ss_dbm)
   average_dbm = 10.0 * log10(average_mw) ;
 
   // Update the variance:
-  variance_m2 += delta * (ss_mw - average_mw) ;
+  variance_mw_m2 += delta * (ss_mw - average_mw) ;
   if (ss_list.size() > 1)
-    variance = variance_m2 / (ss_list.size() - 1) ;
+    variance_mw = variance_mw_m2 / (ss_list.size() - 1) ;
 }
 
 
@@ -223,8 +223,8 @@ Measurement& Measurement::operator=(const Measurement &m)
   ss_list = m.ss_list ;
   average_dbm = m.average_dbm ;
   average_mw = m.average_mw ;
-  variance = m.variance ;
-  variance_m2 = m.variance_m2 ;
+  variance_mw = m.variance_mw ;
+  variance_mw_m2 = m.variance_mw_m2 ;
 
   return *this ;
 }
@@ -288,7 +288,7 @@ ostream &operator<<(ostream &os, const Measurement &m)
         os << static_cast<int_fast16_t>(i->second)
            << '(' << i->first << ')' ;
       }
-  os << " [AVG=" << m.average_dbm << "]" ;
+  os << " [AVG_dBm=" << m.average_dbm << ";AVG_mW=" << m.average_mw << ";VAR_mW=" << m.variance_mw << ";STD_mW=" << m.get_std_deviation_mw() << "]" ;
 
   return os ;
 }

owlps-positioner/src/measurement.hh

@@ -29,12 +29,12 @@ protected:
   float average_dbm ;
   /// Average of all the captured signal strengths (mW)
   float average_mw ;
-  /// Variance of all the captured signal strengths
-  float variance ;
+  /// Variance of all the captured signal strengths (mW)
+  float variance_mw ;
 
 private:
   /// Intermediate variable used to compute the variance
-  float variance_m2 ;
+  float variance_mw_m2 ;
 
 
 protected:
@@ -54,12 +54,12 @@ protected:
 public:
   Measurement(const AccessPoint *_ap = NULL):
     ap(const_cast<AccessPoint*>(_ap)), average_dbm(0),
-    average_mw(0), variance(0), variance_m2(0) {}
+    average_mw(0), variance_mw(0), variance_mw_m2(0) {}
 
   Measurement(const Measurement &source):
     ap(source.ap), ss_list(source.ss_list),
     average_dbm(source.average_dbm), average_mw(source.average_mw),
-    variance(source.variance), variance_m2(0) {}
+    variance_mw(source.variance_mw), variance_mw_m2(0) {}
 
   ~Measurement(void) ;
 
@@ -72,9 +72,9 @@ public:
   /// Returns the mean of the SS list, in dBm
   float get_average_dbm() const ;
   /// Returns the variance of the SS list
-  float get_variance() const ;
+  float get_variance_mw() const ;
   /// Returns the standard deviation of the SS list
-  float get_std_deviation() const ;
+  float get_std_deviation_mw() const ;
   /// Returns the number of SS in the SS list
   int get_nb_ss() const ;
   //@}
@@ -101,10 +101,10 @@ public:
   float ss_square_distance(const Measurement &source) const ;
   /// Computes the distance to another SS value (in dBm)
   float ss_square_distance(const float &ss_dbm) const ;
-  /// Computes the distance to another Measurement's variance
-  float variance_square_distance(const Measurement &source) const ;
-  /// Computes the distance to another variance value
-  float variance_square_distance(const float &var) const ;
+  /// Computes the distance to another Measurement's variance (mW)
+  float variance_mw_square_distance(const Measurement &source) const ;
+  /// Computes the distance to another variance value in mW
+  float variance_mw_square_distance(const float &var) const ;
   //@}
 
   /** @name Operators */
@@ -142,15 +142,15 @@ inline float Measurement::get_average_dbm() const
 }
 
 
-inline float Measurement::get_variance() const
+inline float Measurement::get_variance_mw() const
 {
-  return variance ;
+  return variance_mw ;
 }
 
 
-inline float Measurement::get_std_deviation() const
+inline float Measurement::get_std_deviation_mw() const
 {
-  return sqrt(variance) ;
+  return sqrt(variance_mw) ;
 }
 
 
@@ -188,16 +188,16 @@ inline float Measurement::ss_square_distance(const float &ss_dbm) const
 
 
 inline float Measurement::
-variance_square_distance(const Measurement &source) const
+variance_mw_square_distance(const Measurement &source) const
 {
-  return variance_square_distance(source.variance) ;
+  return variance_mw_square_distance(source.variance_mw) ;
 }
 
 
 inline float Measurement::
-variance_square_distance(const float &var) const
+variance_mw_square_distance(const float &var) const
 {
-  return ((var - variance) * (var - variance)) ;
+  return ((var - variance_mw) * (var - variance_mw)) ;
 }