JFreeChart Boxplot Outlier and Farout appearance

Question

I am using JFreeChart with Java to evaluate experimental results using the boxplot chart. I want to change the color and shape of the outliers and the farout entries.

This is how my plots currently look like when I use the normal BoxAndWhiskerRenderer: I set up the renderer like this:

BoxAndWhiskerRenderer renderer = new BoxAndWhiskerRenderer();
renderer.setFillBox(true);
renderer.setSeriesPaint(0, Color.DARK_GRAY);
renderer.setSeriesPaint(1, Color.LIGHT_GRAY);
renderer.setSeriesOutlinePaint(0, Color.BLACK);
renderer.setSeriesOutlinePaint(1, Color.BLACK);
renderer.setUseOutlinePaintForWhiskers(true);   
Font legendFont = new Font("SansSerif", Font.PLAIN, 15);
renderer.setLegendTextFont(0, legendFont);
renderer.setLegendTextFont(1, legendFont);
renderer.setMeanVisible(false);

Here, I cannot change the color and shape of the outliers. I would want them in black, not in the color of their series. And I would want them to look like small crosses rather than these big empty circles. Also no farout values are shown at all and it seems like one of the outliers is cut off.

Then I found the ExtendedBoxAndWhiskerRenderer which allows to edit the color and shape of both outliers and farouts. This is what that looks like: I set up the renderer like before, but I added two lines to set the color for the outliers and the farout entries:

renderer.setOutlierPaint(Color.BLACK);      renderer.setFaroutPaint(Color.LIGHT_GRAY);

I also experimented with the shape of the outliers by reducing the cirle raduis in the extended renderer's implementation to 1.0 instead of 2.0:

private Shape createEllipse(Point2D point, double oRadius) {
        Ellipse2D dot = new Ellipse2D.Double(point.getX(), point.getY(), oRadius*1.0, oRadius*1.0);
        return dot;
}

However, I don't like these plots too much either. The Whiskers/Outlines of my plots aren't black anymore even though I set them to black. The mean is visible again even though I set it to invisible. And the huge number of outliers looks kind of ridiculous and makes me wonder why there are no farouts at the plots with the normal renderer at all.

If anyone could help me with these smaller appearance problems, that would be very nice. Otherwise, I will just take the current plots with the weird looking outliers and missing farouts...

Answer 1

While ExtendedBoxAndWhiskerRenderer is exemplary, it is somewhat dated, and much of its functionality has been incorporated into the mainline version. Your experiment suggests that the old renderer and new dataset are incompatible.

Because the outlier rendering methods are private, an alternative approach is to override the relevant draw*Item() method and let it invoke your own variations. You'll need to recapitulate the existing code, using the public accessors as required. In outline, the following variations demonstrate using Color.black, illustrated below.

plot.setRenderer(new BoxAndWhiskerRenderer() {

    @Override
    public void drawVerticalItem(Graphics2D g2, …) {
        // existing code that calls the methods below
    }

    private void drawEllipse(Point2D point, double oRadius, Graphics2D g2) {
        Paint temp = g2.getPaint();
        g2.setColor(Color.black);
        Ellipse2D dot = new Ellipse2D.Double(point.getX() + oRadius / 2,
                point.getY(), oRadius, oRadius);
        g2.draw(dot);
        g2.setPaint(temp);
    }

    private void drawHighFarOut(double aRadius, Graphics2D g2, double xx,
            double m) {
        Paint temp = g2.getPaint();
        g2.setColor(Color.black);
        double side = aRadius * 2;
        g2.draw(new Line2D.Double(xx - side, m + side, xx + side, m + side));
        g2.draw(new Line2D.Double(xx - side, m + side, xx, m));
        g2.draw(new Line2D.Double(xx + side, m + side, xx, m));
        g2.setPaint(temp);
    }
}