Java – Setting different y-axis for two series with JFreeChart

javajfreechart

I am using JFreeChart to plot two series of data (XYSeries) using a linechart.
The complicating factor is that one of the data series has y-values that are typically much higher than the y-values of my second data series (let's say that the first series has y-values in the order of magnitude of millions, while the second series has y-values in the order of magnitude of hundreds). The existence of the high values in my first data set cause the range of the plot to be such that the y-values of my second data set are not comprehensible anymore.

Adding a second y-axis to the plot, such that both my data series use their own y-axis, would solve this problem. Does anyone know how to do this with JFreeChart?

Current code for completeness:

XYSeriesCollection dataset = new XYSeriesCollection();
XYSeries series1 = new XYSeries("series1");
XYSeries series2 = new XYSeries("series2");

// Here is my code to fill series1 and series2 with data    

dataset.addSeries(series1);
dataset.addSeries(series2);

JFreeChart chart = ChartFactory.createXYLineChart(
    "title", "x-axis title", "y-axis title", dataset, PlotOrientation.VERTICAL, true, true, false
);
chart.getXYPlot().setRenderer(new XYSplineRenderer());

Best Answer

You can manually create the JFreeChart object instead of using ChartFactory. First generate the datasets and Plot, setting each dataset to an index. Then you can customize the Plot with the necessary Axis and Renderer. Here's an example for doing so with dummy data that has two datasets, each with different magnitude y-values:

    //create the series - add some dummy data
    XYSeries series1 = new XYSeries("series1");
    XYSeries series2 = new XYSeries("series2");
    series1.add(1000, 1000);
    series1.add(1150, 1150);
    series1.add(1250, 1250);

    series2.add(1000, 111250);
    series2.add(1150, 211250);
    series2.add(1250, 311250);

    //create the datasets
    XYSeriesCollection dataset1 = new XYSeriesCollection();
    XYSeriesCollection dataset2 = new XYSeriesCollection();
    dataset1.addSeries(series1);
    dataset2.addSeries(series2);

    //construct the plot
    XYPlot plot = new XYPlot();
    plot.setDataset(0, dataset1);
    plot.setDataset(1, dataset2);

    //customize the plot with renderers and axis
    plot.setRenderer(0, new XYSplineRenderer());//use default fill paint for first series
    XYSplineRenderer splinerenderer = new XYSplineRenderer();
    splinerenderer.setSeriesFillPaint(0, Color.BLUE);
    plot.setRenderer(1, splinerenderer);
    plot.setRangeAxis(0, new NumberAxis("Series 1"));
    plot.setRangeAxis(1, new NumberAxis("Series 2"));
    plot.setDomainAxis(new NumberAxis("X Axis"));

    //Map the data to the appropriate axis
    plot.mapDatasetToRangeAxis(0, 0);
    plot.mapDatasetToRangeAxis(1, 1);   

    //generate the chart
    JFreeChart chart = new JFreeChart("MyPlot", getFont(), plot, true);
    chart.setBackgroundPaint(Color.WHITE);
    JPanel chartPanel = new ChartPanel(chart);

Related Solutions

Java – Creating a time series with jfreechart

You might have a look at org.jfree.chart.demo.TimeSeriesChartDemo1, and the associated API documentation. A typical command to run the demo might look like this:

java -cp lib/jfreechart-1.0.13.jar:lib/jcommon-1.0.16.jar \
org.jfree.chart.demo.TimeSeriesChartDemo1

The example uses org.jfree.data.time.Month to represent monthly data, but other units are available in org.jfree.data.time. See also the approach shown in this related example, which is based on TimeSeriesChartDemo1.

Java – Adding points to XYSeries dynamically with JfreeChart

You can add new values to the XYSeries using one of the available add() methods, as shown in this example. If you're getting adventitious rows, you'll need to post an sscce.

Addendum: Looking more closely at the (recently updated) genesis of your example, some confusion is understandable: no array is needed at all. The example below includes a button that adds new samples to a second series.

Can I change the Color of Points when I click the "Add" Button?

Each new series is a new color, as shown in this example. To change individual colors, the recommended way is to override the renderer's getItemPaint() method, as shown here.

ScatterAdd

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.util.*;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.jfree.chart.*;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYItemRenderer;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

/**
 * @see https://stackoverflow.com/questions/7205742
 * @see https://stackoverflow.com/questions/7208657
 * @see https://stackoverflow.com/questions/7071057
 */
public class ScatterAdd extends JFrame {

    private static final int N = 8;
    private static final String title = "Scatter Add Demo";
    private static final Random rand = new Random();
    private XYSeries added = new XYSeries("Added");

    public ScatterAdd(String s) {
        super(s);
        final ChartPanel chartPanel = createDemoPanel();
        this.add(chartPanel, BorderLayout.CENTER);
        JPanel control = new JPanel();
        control.add(new JButton(new AbstractAction("Add") {

            @Override
            public void actionPerformed(ActionEvent e) {
                for (int i = 0; i < N; i++) {
                    added.add(rand.nextGaussian(), rand.nextGaussian());
                }
            }
        }));
        this.add(control, BorderLayout.SOUTH);
    }

    private ChartPanel createDemoPanel() {
        JFreeChart jfreechart = ChartFactory.createScatterPlot(
            title, "X", "Y", createSampleData(),
            PlotOrientation.VERTICAL, true, true, false);
        XYPlot xyPlot = (XYPlot) jfreechart.getPlot();
        xyPlot.setDomainCrosshairVisible(true);
        xyPlot.setRangeCrosshairVisible(true);
        XYItemRenderer renderer = xyPlot.getRenderer();
        renderer.setSeriesPaint(0, Color.blue);
        NumberAxis domain = (NumberAxis) xyPlot.getDomainAxis();
        domain.setVerticalTickLabels(true);
        return new ChartPanel(jfreechart);
    }

    private XYDataset createSampleData() {
        XYSeriesCollection xySeriesCollection = new XYSeriesCollection();
        XYSeries series = new XYSeries("Random");
        for (int i = 0; i < N * N; i++) {
            double x = rand.nextGaussian();
            double y = rand.nextGaussian();
            series.add(x, y);
        }
        xySeriesCollection.addSeries(series);
        xySeriesCollection.addSeries(added);
        return xySeriesCollection;
    }

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

            @Override
            public void run() {
                ScatterAdd demo = new ScatterAdd(title);
                demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                demo.pack();
                demo.setLocationRelativeTo(null);
                demo.setVisible(true);
            }
        });
    }
}

Best Answer

Related Solutions

Java – Creating a time series with jfreechart

Java – Adding points to XYSeries dynamically with JfreeChart

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