JFreeChart scaling of Boxplots with several Categories

Question

i am currently working on a java-based project using JFreeChart to display boxplots.

My Problem is how to display a chart containing boxplots for a CategoryDataset with about 20 Categories and 5+ Series.

Currently if the preferred size of the ChartPanel is not set, the Legend, Labels and Annotations are readable but the Boxplots are too small. Or the size of the ChartPanel is set so that the Boxplots have an acceptable size but then the legend, labels and annotations are horizontally stretched.

My question is, how to correctly scale the boxplots without scaling the legend, axis Labels and annotations of the Chart? Is it possible to scale the Plot without scaling all the elements of the Chart?

Code Example

import java.awt.Color;
import java.awt.Dimension;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;

import javax.swing.JFrame;
import javax.swing.JScrollPane;

import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.renderer.category.BoxAndWhiskerRenderer;
import org.jfree.data.statistics.DefaultBoxAndWhiskerCategoryDataset;


public class StretchedBoxAndWhiskerExample{

DefaultBoxAndWhiskerCategoryDataset dataset;
JFreeChart chart;
ChartPanel chartPanel;
JFrame frame;
JScrollPane scrollPane;

public StretchedBoxAndWhiskerExample() {
    createCategoryBoxplot();

    frame = new JFrame();
    scrollPane = new JScrollPane(chartPanel);
    scrollPane.setPreferredSize(new Dimension(800,700));
    scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
    frame.add(scrollPane);
    frame.pack();
    frame.setVisible(true);
}

private void createCategoryBoxplot(){   
    dataset = createCategoryDataset();
    CategoryAxis xAxis = new CategoryAxis("");
    NumberAxis yAxis = new NumberAxis("Score");

    BoxAndWhiskerRenderer renderer = new BoxAndWhiskerRenderer();
    CategoryPlot plot = new CategoryPlot(dataset, xAxis, yAxis, renderer);
    createJFreeChart(plot,"Test");

    // Design
    renderer.setFillBox(false);
    renderer.setMeanVisible(false);

    chart.setBackgroundPaint(Color.white); 
    plot.setBackgroundPaint(Color.lightGray); 
    plot.setDomainGridlinePaint(Color.white); 
    plot.setDomainGridlinesVisible(true); 
    plot.setRangeGridlinePaint(Color.white);
    plot.getRangeAxis().setRange(-10.5, 10.5);


    chartPanel = new ChartPanel(chart);
    chartPanel.setPreferredSize(new Dimension(3250,600));
}

private DefaultBoxAndWhiskerCategoryDataset createCategoryDataset() {

    dataset = new DefaultBoxAndWhiskerCategoryDataset();
    ArrayList<Double> values = createSampleData();
    ArrayList<String> categories = createSampleCategories();
    for (int i=0;i<=5;i++){
        for (String category : categories){
            dataset.add(values,i,category);
        }
    }
    return dataset;
}


private ArrayList<String> createSampleCategories() {
    ArrayList<String> tmp = new ArrayList<String>();
    for (int i=0;i<=20;i++){
        tmp.add("Category"+i);
    }
    return tmp;
}

private ArrayList<Double> createSampleData() {
    ArrayList<Double> tmp = new ArrayList<Double>();
    for (int i=0;i<10;i++){
        tmp.add(5.0);
        tmp.add(7.0);
        tmp.add(2.0);
        tmp.add(4.0);
    }
    return tmp;
}

private void createJFreeChart(CategoryPlot plot, String title){
    chart = new JFreeChart(title, plot);
}

public static void main(String[] args) throws IOException { 
    StretchedBoxAndWhiskerExample demo = new StretchedBoxAndWhiskerExample();

}
}

Answer 1

Set the preferred size of the containing ChartPanel, not the chart, as shown here and here.

Addendum: I don't think you can usefully add a chart to a scroll pane. Instead, create a class similar to SlidingCategoryDataset that implements BoxAndWhiskerCategoryDataset. Add a scroll bar to the frame that controls the first displayed index.

Addendum: A somewhat less ambitious approach is simply to page a portion of the data set using some suitable control, as shown in the example below.

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.renderer.category.BoxAndWhiskerRenderer;
import org.jfree.data.statistics.DefaultBoxAndWhiskerCategoryDataset;

/** @see https://stackoverflow.com/questions/6844759 */
public class BoxAndWhiskerDemo {

    private static final int COLS = 20;
    private static final int VISIBLE = 4;
    private static final int ROWS = 5;
    private static final int VALUES = 10;
    private static final Random rnd = new Random();
    private List<String> columns;
    private List<List<List<Double>>> data;
    private DefaultBoxAndWhiskerCategoryDataset dataset;
    private CategoryPlot plot;
    private ChartPanel chartPanel;
    private JPanel controlPanel;
    private int start = 0;

    public BoxAndWhiskerDemo() {
        createData();
        createDataset(start);
        createChartPanel();
        createControlPanel();
    }

    private void createData() {
        columns = new ArrayList<String>(COLS);
        data = new ArrayList<List<List<Double>>>();
        for (int i = 0; i < COLS; i++) {
            String name = "Category" + String.valueOf(i + 1);
            columns.add(name);
            List<List<Double>> list = new ArrayList<List<Double>>();
            for (int j = 0; j < ROWS; j++) {
                list.add(createValues());
            }
            data.add(list);
        }
    }

    private List<Double> createValues() {
        List<Double> list = new ArrayList<Double>();
        for (int i = 0; i < VALUES; i++) {
            list.add(rnd.nextGaussian());
        }
        return list;
    }

    private void createDataset(int start) {
        dataset = new DefaultBoxAndWhiskerCategoryDataset();
        for (int i = start; i < start + VISIBLE; i++) {
            List<List<Double>> list = data.get(i);
            int row = 0;
            for (List<Double> values : list) {
                String category = columns.get(i);
                dataset.add(values, "s" + row++, category);
            }
        }
    }

    private void createChartPanel() {
        CategoryAxis xAxis = new CategoryAxis("Category");
        NumberAxis yAxis = new NumberAxis("Value");
        BoxAndWhiskerRenderer renderer = new BoxAndWhiskerRenderer();
        plot = new CategoryPlot(dataset, xAxis, yAxis, renderer);
        JFreeChart chart = new JFreeChart("BoxAndWhiskerDemo", plot);
        chartPanel = new ChartPanel(chart);
    }

    private void createControlPanel() {
        controlPanel = new JPanel();
        controlPanel.add(new JButton(new AbstractAction("\u22b2Prev") {

            @Override
            public void actionPerformed(ActionEvent e) {
                start -= VISIBLE;
                if (start < 0) {
                    start = 0;
                    return;
                }
                createDataset(start);
                plot.setDataset(dataset);
            }
        }));
        controlPanel.add(new JButton(new AbstractAction("Next\u22b3") {

            @Override
            public void actionPerformed(ActionEvent e) {
                start += VISIBLE;
                if (start > COLS - VISIBLE) {
                    start = COLS - VISIBLE;
                    return;
                }
                createDataset(start);
                plot.setDataset(dataset);
            }
        }));
    }

    public ChartPanel getChartPanel() {
        return chartPanel;
    }

    public JPanel getControlPanel() {
        return controlPanel;
    }

    public static void main(String[] args) throws IOException {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                BoxAndWhiskerDemo demo = new BoxAndWhiskerDemo();
                frame.add(demo.getChartPanel(), BorderLayout.CENTER);
                frame.add(demo.getControlPanel(), BorderLayout.SOUTH);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}