How can I create a bar-chart with JFreeChart, that shortens too long bars with a visible hint?

Question

I want to create a bar-chart, but extraordinary high values should be shortened. An example is this image:

_{(source: epa.gov)}

I hope it is clear what I want.

My question is: How can I do this with JFreeChart. If it isn't possible with JFreeChart you can possibly recommend alternative open-source Java-libraries to produce such an output.

Croton

Answer 1

You could do it with a CombinedDomainCategoryPlot or CombinedDomainXYPlot. Set the range axis of the first plot to your cut off value and then do something similar with the second plot. Then add them to a combined plot.

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartFrame;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.CombinedDomainCategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.DefaultCategoryDataset;

public class PlayChart {

    public static void main(String[] args) {


        DefaultCategoryDataset ds = new DefaultCategoryDataset();
        ds.addValue(100, "A", "A");
        ds.addValue(200, "A", "B");
        ds.addValue(400, "A", "C");
        ds.addValue(500, "A", "D");
        ds.addValue(2000, "A", "E");


        JFreeChart bc = ChartFactory.createBarChart("My Bar Chart", "Things", "Counts",  ds, PlotOrientation.VERTICAL, true, false, false);
        JFreeChart bcTop = ChartFactory.createBarChart("My Bar Chart", "Things", "Counts",  ds, PlotOrientation.VERTICAL, true, false, false);

        CombinedDomainCategoryPlot combinedPlot = new CombinedDomainCategoryPlot();
        CategoryPlot topPlot = bcTop.getCategoryPlot();
        NumberAxis topAxis = (NumberAxis) topPlot.getRangeAxis();
        topAxis.setLowerBound(1500);
        topAxis.setUpperBound(2000);

        combinedPlot.add(topPlot, 1);
        CategoryPlot mainPlot = bc.getCategoryPlot();
        combinedPlot.add(mainPlot, 5);

        NumberAxis mainAxis = (NumberAxis) mainPlot.getRangeAxis();;
        mainAxis.setLowerBound(0);
        mainAxis.setUpperBound(600);

        JFreeChart combinedChart = new JFreeChart("Test", combinedPlot);

        ChartFrame cf = new ChartFrame("Test", combinedChart);
        cf.setSize(800, 600);
        cf.setVisible(true);

    }

}

The plots will share the same X-axis. You'll need to play with the renderers to set colours and labels.

removed dead ImageShack link

Balliett

Great, that looks exactly as wished, thanks for the fast help. – Croton

I know it was a long time ago, but this is an incredibly thorough answer. – Bipolar

Answer 2

I'm not sure you can do that in JFreeChart.

A solution (which is not nice) is to render the chart to an image and then manipulate it (chop it up etc.) as an image, using RenderedImage, and not as a JFreeChart. Unfortunately that's going to be a bit of a pain since you'd probably want to chop at a particular place on the y-axis etc.

Weswesa