Plotting irregular-period data on time axis in JFreeChart

Question

I am trying to create a line chart using JfreeChart API. The x axis receives data as long (milliseconds) and Y axis as a double. As I am using the dynamic template I am passing data to it via Add_Point method from separate thread and chart is constantly updated via this method. Data comes in irregularly without any periodicity which perhaps makes it even trickier.

I cannot find a way to convert long into digestible for Jfreechart format without working example of it. It seems that I have exhausted all options but my guess is that there are a lot of people out there who have already been through this and have a ready answer.

All I want to do is to reflect correct time on X axis labels every minute with data points correctly spaced over respective point in time. By correct time I mean long value passed to method and not current system time.

Here is the code:

import java.awt.BorderLayout;
import javax.swing.JPanel;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.time.FixedMillisecond;
import org.jfree.data.time.Millisecond;
import org.jfree.data.time.RegularTimePeriod;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;
import org.jfree.ui.ApplicationFrame;


public class DynamicDataDemo extends ApplicationFrame {

    /** The time series data. */
    private static TimeSeries series;

    public DynamicDataDemo(final String title) {

        super(title);
        this.series = new TimeSeries("Random Data", Millisecond.class);
        final TimeSeriesCollection dataset = new TimeSeriesCollection(this.series);
        final JFreeChart chart = createChart(dataset);

        final ChartPanel chartPanel = new ChartPanel(chart);

        final JPanel content = new JPanel(new BorderLayout());
        content.add(chartPanel);
        chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));
        setContentPane(content);

    }

    private JFreeChart createChart(final XYDataset dataset) {
        final JFreeChart result = ChartFactory.createTimeSeriesChart(
            "Dynamic Data Demo", 
            "Time", 
            "Value",
            dataset, 
            true, 
            true, 
            false
        );
        final XYPlot plot = result.getXYPlot();
        ValueAxis axis = plot.getDomainAxis();
        axis.setAutoRange(true);
        axis.setFixedAutoRange(60000.0);  // 60 seconds
        axis = plot.getRangeAxis();
        axis.setRange(9000.0, 11000.0); 
        return result;
    }


    public static void Add_Point(long x, double y){
        series.add(new Millisecond(), y);
//      series.add(new FixedMillisecond(x), y);    }

}

Hello Peter, good to hear from you. I have been pouring over the Chronicle API - thanks to you! This has started me off in the direction 'How can I replay all the data I have in Chronicle into something more visual?' And I have not contacted their support as I am using the free version. — les
What some do is hook up something like Chronicle-Websocket-Jetty to a javascript client which does the charting. The JS can send commands to extract information from the Queue or Map to display. — Peter Lawrey

Catalina Island Catalina Island · Accepted Answer · 2016-02-17T15:38:04

If your x values are milliseconds from the Java epoch, you can do it like this:

series.add(new Millisecond(new Date(x)), y);

If not, you'll have to scale and/or offset the value.

Plotting irregular-period data on time axis in JFreeChart

1 Answers