void RangeProfilePlotManager::calculateDifferences()
{
   // ensure we have only two objects selected
   VERIFYNRV(mpView);
   std::list<PlotObject*> selected;
   mpView->getSelectedObjects(selected, true);
   std::list<PlotObject*>::iterator selIt = selected.begin();
   PointSet* pFirst = (selIt == selected.end()) ? NULL : dynamic_cast<PointSet*>(*(selIt++));
   PointSet* pSecond = (selIt == selected.end()) ? NULL : dynamic_cast<PointSet*>(*(selIt++));
   if (pFirst == NULL || pSecond == NULL)
   {
      return;
   }

   // locate the Difference point set
   std::list<PlotObject*> allObjects;
   mpView->getObjects(POINT_SET, allObjects);
   PointSet* pDiffSet = NULL;
   for (std::list<PlotObject*>::iterator obj = allObjects.begin(); obj != allObjects.end(); ++obj)
   {
      PointSet* pSet = static_cast<PointSet*>(*obj);
      std::string name;
      pSet->getObjectName(name);
      if (name == "Difference")
      {
         pDiffSet = pSet;
         pDiffSet->clear(true);
         break;
      }
   }
   if (pDiffSet == NULL)
   {
      pDiffSet = static_cast<PointSet*>(mpView->addObject(POINT_SET, true));
      pDiffSet->setObjectName("Difference");
   }

   // calculate the differences and errors
   std::vector<Point*> aPoints = pFirst->getPoints();
   std::vector<Point*> bPoints = pSecond->getPoints();
   if (aPoints.size() < 2 || bPoints.size() < 2)
   {
      return;
   }
   double mae = 0.0;
   double mse1 = 0.0;
   double mse2 = 0.0;

   for (size_t aIdx = 0; aIdx < aPoints.size(); ++aIdx)
   {
      Point* pA = aPoints[aIdx];
      VERIFYNRV(pA);
      LocationType aVal = pA->getLocation();
      LocationType newVal;

      // locate the associated spot in b
      for (size_t bIdx = 0; bIdx < bPoints.size(); ++bIdx)
      {
         Point* pB = bPoints[bIdx];
         VERIFYNRV(pB);
         LocationType bVal = pB->getLocation();
         double diff = aVal.mX - bVal.mX;
         if (fabs(diff) < 0.0000001) // a == b   use the exact value
         {
            newVal.mX = aVal.mX;
            newVal.mY = bVal.mY - aVal.mY;
            break;
         }
         else if (diff < 0.0) // a < b   found the upper point, interpolate
         {
            newVal.mX = aVal.mX;
            LocationType secondBVal;
            if (bIdx == 0) // we are at the start so continue the segment from the right
            {
               Point* pSecondB = bPoints[1];
               VERIFYNRV(pSecondB);
               secondBVal = pSecondB->getLocation();
            }
            else // grab the previous point for interpolation
            {
               Point* pSecondB = bPoints[bIdx-1];
               VERIFYNRV(pSecondB);
               secondBVal = pSecondB->getLocation();
            }

            // calculate slope-intercept
            double m = (bVal.mY - secondBVal.mY) / (bVal.mX - secondBVal.mX);
            double b = bVal.mY - m * bVal.mX;

            // find the y corresponding to the interpolated x
            newVal.mY = m * newVal.mX + b;
            newVal.mY -= aVal.mY;
            break;
         }
      }
      mae += fabs(newVal.mY);
      mse1 += newVal.mY * newVal.mY;
      mse2 += (newVal.mY * newVal.mY) / (aVal.mY * aVal.mY);
      pDiffSet->addPoint(newVal.mX, newVal.mY);
   }
   pDiffSet->setLineColor(ColorType(200, 0, 0));
   mpView->refresh();
   mae /= aPoints.size();
   mse1 /= aPoints.size();
   mse2 /= aPoints.size();
   QMessageBox::information(mpView->getWidget(), "Comparison metrics",
      QString("Mean squared error (method 1): %1\n"
              "Mean squared error (method 2): %2\n"
              "Mean absolute error:           %3").arg(mse1).arg(mse2).arg(mae), QMessageBox::Close);
}
bool RangeProfilePlotManager::plotProfile(Signature* pSignature)
{
   VERIFY(mpView && pSignature);
   std::string plotName = pSignature->getDisplayName();
   if (plotName.empty())
   {
      plotName = pSignature->getName();
   }
   if (plotName == "Difference")
   {
      QMessageBox::warning(Service<DesktopServices>()->getMainWidget(),
         "Invalid signature", "Signatures can not be named 'Difference' as this is a reserved "
                              "name for this plot. Please rename your signature and try again.");
      return false;
   }
   const Units* pXUnits = NULL;
   const Units* pYUnits = NULL;
   std::vector<double> xData;
   std::vector<double> yData;
   std::set<std::string> dataNames = pSignature->getDataNames();
   for (std::set<std::string>::const_iterator dataName = dataNames.begin();
      dataName != dataNames.end() && (pXUnits == NULL || pYUnits == NULL);
      ++dataName)
   {
      const Units* pUnits = pSignature->getUnits(*dataName);
      if (pUnits == NULL)
      {
         continue;
      }
      if (pUnits->getUnitType() == DISTANCE)
      {
         if (pXUnits == NULL)
         {
            pXUnits = pUnits;
            xData = dv_cast<std::vector<double> >(pSignature->getData(*dataName), std::vector<double>());
         }
      }
      else if (pYUnits == NULL)
      {
         pYUnits = pUnits;
         yData = dv_cast<std::vector<double> >(pSignature->getData(*dataName), std::vector<double>());
      }
   }
   if (xData.empty() || xData.size() != yData.size())
   {
      QMessageBox::warning(Service<DesktopServices>()->getMainWidget(),
         "Invalid signature", QString("Signatures must have a distance axis. '%1' does not and will not be plotted.")
                                 .arg(QString::fromStdString(pSignature->getName())));
      return false;
   }
   std::map<Signature*, std::string>::iterator oldPointSet = mSigPointSets.find(pSignature);
   PointSet* pSet = getPointSet(pSignature);
   if (pSet != NULL)
   {
      pSet->clear(true);
   }
   std::list<PlotObject*> curObjects;
   mpView->getObjects(POINT_SET, curObjects);
   if (pSet == NULL)
   {
      std::vector<ColorType> excluded;
      excluded.push_back(ColorType(255, 255, 255)); // background
      excluded.push_back(ColorType(200, 0, 0)); // color for the difference plot
      for (std::list<PlotObject*>::const_iterator cur = curObjects.begin(); cur != curObjects.end(); ++cur)
      {
         excluded.push_back(static_cast<PointSet*>(*cur)->getLineColor());
      }
      pSet = static_cast<PointSet*>(mpView->addObject(POINT_SET, true));
      mSigPointSets[pSignature] = plotName;
      pSignature->attach(SIGNAL_NAME(Subject, Deleted), Slot(this, &RangeProfilePlotManager::signatureDeleted));
      pSignature->getDataDescriptor()->attach(SIGNAL_NAME(DataDescriptor, Renamed),
         Slot(this, &RangeProfilePlotManager::signatureRenamed));
      std::vector<ColorType> colors;
      ColorType::getUniqueColors(1, colors, excluded);
      if (!colors.empty())
      {
         pSet->setLineColor(colors.front());
      }
   }
   pSet->setObjectName(plotName);
   for (size_t idx = 0; idx < xData.size(); ++idx)
   {
      pSet->addPoint(xData[idx], yData[idx]);
   }

   VERIFY(mpPlot);
   Axis* pBottom = mpPlot->getAxis(AXIS_BOTTOM);
   Axis* pLeft = mpPlot->getAxis(AXIS_LEFT);
   VERIFYRV(pBottom && pLeft, NULL);
   if (pBottom->getTitle().empty())
   {
      pBottom->setTitle(pXUnits->getUnitName());
   }
   if (pLeft->getTitle().empty())
   {
      pLeft->setTitle(pYUnits->getUnitName());
   }
   else if (pLeft->getTitle() != pYUnits->getUnitName())
   {
      Axis* pRight = mpPlot->getAxis(AXIS_RIGHT);
      VERIFYRV(pRight, NULL);
      if (pRight->getTitle().empty())
      {
         pRight->setTitle(pYUnits->getUnitName());
      }
   }

   std::string classificationText = dv_cast<std::string>(pSignature->getMetadata()->getAttribute("Raw Classification"),
      mpPlot->getClassificationText());
   if (classificationText.empty() == false)
   {
      FactoryResource<Classification> pClassification;
      if (pClassification->setClassification(classificationText) == true)
      {
         mpPlot->setClassification(pClassification.get());
      }
      else
      {
         QMessageBox::warning(Service<DesktopServices>()->getMainWidget(), QString::fromStdString(getName()),
            "The plot could not be updated with the signature classification.  Please ensure that the plot "
            "has the proper classification.");
      }
   }

   getDockWindow()->show();
   mpView->zoomExtents();
   mpView->refresh();

   return true;
}