[Positioning] Result: compute error if possible

If the real coordinates are passed to the constructor, the distance
error is computed. One can also use Result::compute_error() on a
constructed object.

owlps-positioning/src/result.cc

@@ -7,6 +7,28 @@ using namespace std ;
 
 
 
+/* *** Constructors *** */
+
+
+Result::Result(const Point3D &_position, const std::string &_algorithm,
+               const Point3D &real_position):
+  position(_position), algorithm(_algorithm)
+{
+  compute_error(real_position) ;
+}
+
+
+
+/* *** Write accessors *** */
+
+
+void Result::compute_error(const Point3D &real_position)
+{
+  error = position.distance(real_position) ;
+}
+
+
+
 /* *** Operators *** */
 
 
@@ -42,7 +64,9 @@ const string Result::to_csv() const
       << algorithm
       << ';' << position.get_x()
       << ';' << position.get_y()
-      << ';' << position.get_z() ;
+      << ';' << position.get_z()
+      << ';' << "Error"
+      << ';' << error ;
 
   return csv_line.str() ;
 }
@@ -54,5 +78,7 @@ std::ostream& operator<<(ostream &os, const Result &r)
   os
       << "The result of the algorithm " << r.algorithm
       << " is: " << r.position ;
+  if (r.error >= 0)
+    os << ", error = " << r.error << " m" ;
   return os ;
 }

owlps-positioning/src/result.hh

@@ -9,20 +9,33 @@
 class Result
 {
 protected:
+  /// Computed coordinates of the mobile
   Point3D position ;
+  /// Algorithm used to compute the position
   std::string algorithm ;
+  /// Distance error between the real coordinates and the computed point
+  /** The error is set to -1 if the real coordinates are unknown. */
+  float error ;
 
 public:
   Result(const std::string &_algorithm = "UnknownAlgorithm"):
-    algorithm(_algorithm) {}
+    algorithm(_algorithm), error(-1) {}
   Result(const Point3D &_position, const std::string &_algorithm):
-    position(_position), algorithm(_algorithm) {}
+    position(_position), algorithm(_algorithm), error(-1) {}
+  Result(const Point3D &_position, const std::string &_algorithm,
+         const Point3D &real_position) ;
   ~Result(void) {}
 
   /** @name Read accessors */
   //@{
   const std::string& get_algorithm(void) const ;
   const Point3D& get_position(void) const ;
+  float get_error(void) const ;
+  //@}
+
+  /** @name Write accessors */
+  //@{
+  void compute_error(const Point3D &real_position) ;
   //@}
 
   /** @name Operators */
@@ -59,6 +72,12 @@ inline const Point3D& Result::get_position() const
 }
 
 
+inline float Result::get_error() const
+{
+  return error ;
+}
+
+
 
 /* *** Operators *** */