statistics: make confidence area and regression line opt-in

This is not perfect - the polygon of the confidence area is
calculated even if it is not shown. Oh well.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

stats/regressionitem.cpp

@@ -11,7 +11,8 @@ static const double regressionLineWidth = 2.0;
 RegressionItem::RegressionItem(StatsView &view, regression_data reg,
 						   StatsAxis *xAxis, StatsAxis *yAxis) :
 	ChartPixmapItem(view, ChartZValue::ChartFeatures),
-	xAxis(xAxis), yAxis(yAxis), reg(reg)
+	xAxis(xAxis), yAxis(yAxis), reg(reg),
+	regression(true), confidence(true)
 {
 }
 
@@ -19,6 +20,16 @@ RegressionItem::~RegressionItem()
 {
 }
 
+void RegressionItem::setFeatures(bool regressionIn, bool confidenceIn)
+{
+	if (regressionIn == regression && confidenceIn == confidence)
+		return;
+	regression = regressionIn;
+	confidence = confidenceIn;
+	updatePosition();
+}
+
+// Note: this calculates the confidence area, even if it isn't shown. Might want to optimize this.
 void RegressionItem::updatePosition()
 {
 	if (!xAxis || !yAxis)
@@ -74,14 +85,18 @@ void RegressionItem::updatePosition()
 	ChartPixmapItem::resize(QSizeF(screenMaxX - screenMinX, screenMaxY - screenMinY));
 
 	img->fill(Qt::transparent);
+	if (confidence) {
 		QColor col(regressionItemColor);
 		col.setAlphaF(reg.r2);
 		painter->setPen(Qt::NoPen);
 		painter->setBrush(QBrush(col));
 		painter->drawPolygon(poly);
+	}
 
+	if (regression) {
 		painter->setPen(QPen(regressionItemColor, regressionLineWidth));
 		painter->drawLine(QPointF(linePolygon[0]), QPointF(linePolygon[1]));
+	}
 
 	ChartPixmapItem::setPos(offset);
 }

stats/regressionitem.h

@@ -18,9 +18,11 @@ public:
 	RegressionItem(StatsView &view, regression_data data, StatsAxis *xAxis, StatsAxis *yAxis);
 	~RegressionItem();
 	void updatePosition();
+	void setFeatures(bool regression, bool confidence);
 private:
 	StatsAxis *xAxis, *yAxis;
 	regression_data reg;
+	bool regression, confidence;
 };
 
 #endif

stats/statsstate.cpp

@@ -28,6 +28,8 @@ static const int ChartFeatureLegend =	 1 << 1;
 static const int ChartFeatureMedian =	  1 << 2;
 static const int ChartFeatureMean =	  1 << 3;
 static const int ChartFeatureQuartiles =  1 << 4;
+static const int ChartFeatureRegression = 1 << 5;
+static const int ChartFeatureConfidence = 1 << 6;
 
 static const struct ChartTypeDesc {
 	ChartType id;
@@ -45,7 +47,7 @@ static const struct ChartTypeDesc {
 		SupportedVariable::Numeric,
 		false, false, false,
 		{ ChartSubType::Dots },
-		0
+		ChartFeatureRegression | ChartFeatureConfidence
 	},
 	{
 		ChartType::HistogramCount,
@@ -161,6 +163,8 @@ StatsState::StatsState() :
 	median(false),
 	mean(false),
 	quartiles(true),
+	regression(true),
+	confidence(true),
 	var1Binner(nullptr),
 	var2Binner(nullptr),
 	var2Operation(StatsOperation::Invalid)
@@ -353,19 +357,23 @@ static StatsState::VariableList createOperationsList(const StatsVariable *var, S
 	return res;
 }
 
-static std::vector<StatsState::Feature> createFeaturesList(int chartFeatures, bool labels, bool legend, bool median, bool mean, bool quartiles)
+static std::vector<StatsState::Feature> createFeaturesList(int chartFeatures, const StatsState &state)
 {
 	std::vector<StatsState::Feature> res;
 	if (chartFeatures & ChartFeatureLabels)
-		res.push_back({ StatsTranslations::tr("labels"), ChartFeatureLabels, labels });
+		res.push_back({ StatsTranslations::tr("labels"), ChartFeatureLabels, state.labels });
 	if (chartFeatures & ChartFeatureLegend)
-		res.push_back({ StatsTranslations::tr("legend"), ChartFeatureLegend, legend });
+		res.push_back({ StatsTranslations::tr("legend"), ChartFeatureLegend, state.legend });
 	if (chartFeatures & ChartFeatureMedian)
-		res.push_back({ StatsTranslations::tr("median"), ChartFeatureMedian, median });
+		res.push_back({ StatsTranslations::tr("median"), ChartFeatureMedian, state.median });
 	if (chartFeatures & ChartFeatureMean)
-		res.push_back({ StatsTranslations::tr("mean"), ChartFeatureMean, mean });
+		res.push_back({ StatsTranslations::tr("mean"), ChartFeatureMean, state.mean });
 	if (chartFeatures & ChartFeatureQuartiles)
-		res.push_back({ StatsTranslations::tr("quartiles"), ChartFeatureQuartiles, quartiles });
+		res.push_back({ StatsTranslations::tr("quartiles"), ChartFeatureQuartiles, state.quartiles });
+	if (chartFeatures & ChartFeatureRegression)
+		res.push_back({ StatsTranslations::tr("linear regression"), ChartFeatureRegression, state.regression });
+	if (chartFeatures & ChartFeatureConfidence)
+		res.push_back({ StatsTranslations::tr("95% confidence area"), ChartFeatureConfidence, state.confidence });
 	return res;
 }
 
@@ -381,7 +389,7 @@ StatsState::UIState StatsState::getUIState() const
 	// Second variable can only be binned if first variable is binned.
 	res.binners2 = createBinnerList(var2, var2Binner, var1Binner != nullptr, true);
 	res.operations2 = createOperationsList(var2, var2Operation, var1Binner);
-	res.features = createFeaturesList(chartFeatures, labels, legend, median, mean, quartiles);
+	res.features = createFeaturesList(chartFeatures, *this);
 	return res;
 }
 
@@ -471,6 +479,10 @@ void StatsState::featureChanged(int id, bool state)
 		mean = state;
 	else if (id == ChartFeatureQuartiles)
 		quartiles = state;
+	else if (id == ChartFeatureRegression)
+		regression = state;
+	else if (id == ChartFeatureConfidence)
+		confidence = state;
 }
 
 // Creates the new chart-type from the current chart-type and a list of possible chart types.

stats/statsstate.h

@@ -108,6 +108,8 @@ public:
 	bool median;
 	bool mean;
 	bool quartiles;
+	bool regression;
+	bool confidence;
 	const StatsBinner *var1Binner;	// nullptr: undefined
 	const StatsBinner *var2Binner;	// nullptr: undefined
 	StatsOperation var2Operation;

stats/statsview.cpp

@@ -460,6 +460,11 @@ void StatsView::updateFeatures()
 	if (medianMarker)
 		medianMarker->setVisible(state.median);
 
+	if (regressionItem) {
+		regressionItem->setVisible(state.regression || state.confidence);
+		if (state.regression || state.confidence)
+			regressionItem->setFeatures(state.regression, state.confidence);
+	}
 	for (ChartItemPtr<QuartileMarker> &marker: quartileMarkers)
 		marker->setVisible(state.quartiles);
 }