JFreeChart - TimeSeries Chart


Advertisements


A time series chart displays sequence of data points, which varies at equal intervals of time. This chapter demonstrates how we can use JFreeChart to create Time Series Chart from a given set of business data.

Business Data

Let us consider various random numbers generated by using standard Java API Math.random(). We use these numbers to generate a Time Series Chart. You can generate similar chart for total number of errors occurring in your website at a given interval of time.

AWT Based Application

Following is the code to create Time Series Chart from the numbers generated by Math.random() at a given time internal.

import org.jfree.chart.ChartFactory; 
import org.jfree.chart.ChartPanel; 
import org.jfree.chart.JFreeChart; 
import org.jfree.data.general.SeriesException; 
import org.jfree.data.time.Second; 
import org.jfree.data.time.TimeSeries; 
import org.jfree.data.time.TimeSeriesCollection; 
import org.jfree.data.xy.XYDataset; 
import org.jfree.ui.ApplicationFrame; 
import org.jfree.ui.RefineryUtilities;

public class TimeSeries_AWT extends ApplicationFrame 
{
   public TimeSeries_AWT( final String title )
   {
      super( title );         
      final XYDataset dataset = createDataset( );         
      final JFreeChart chart = createChart( dataset );         
      final ChartPanel chartPanel = new ChartPanel( chart );         
      chartPanel.setPreferredSize( new java.awt.Dimension( 560 , 370 ) );         
      chartPanel.setMouseZoomable( true , false );         
      setContentPane( chartPanel );
   }

   private XYDataset createDataset( ) 
   {
      final TimeSeries series = new TimeSeries( "Random Data" );         
      Second current = new Second( );         
      double value = 100.0;         
      for (int i = 0; i < 4000; i++)    
      {
         try 
         {
            value = value + Math.random( ) - 0.5;                 
            series.add(current, new Double( value ) );                 
            current = ( Second ) current.next( ); 
         }
         catch ( SeriesException e ) 
         {
            System.err.println("Error adding to series");
         }
      }

      return new TimeSeriesCollection(series);
   }     

   private JFreeChart createChart( final XYDataset dataset ) 
   {
      return ChartFactory.createTimeSeriesChart(             
      "Computing Test", 
      "Seconds",              
      "Value",              
      dataset,             
      false,              
      false,              
      false);
   }

   public static void main( final String[ ] args )
   {
      final String title = "Time Series Management";         
      final TimeSeries_AWT demo = new TimeSeries_AWT( title );         
      demo.pack( );         
      RefineryUtilities.positionFrameRandomly( demo );         
      demo.setVisible( true );
   }
}   

Let us keep the above Java code in TimeSeries_AWT.java file, and then compile and run it from command prompt as follows :

$javac TimeSeries_AWT.java 
$java TImeSeries_AWT 

If everything is fine , it will compile and run to generate the following Time Series Graph :

JFreeChart TimeSeries Chart

JPEG Image Creation

Let us re-write above example to generate a JPEG image from command line.

import java.io.*;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.data.general.SeriesException;
import org.jfree.data.time.Second;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;
import org.jfree.chart.ChartUtilities;

public class TimeSeriesChart
{
   public static void main( final String[ ] args )throws Exception
   {
      final TimeSeries series = new TimeSeries( "Random Data" );
      Second current = new Second();
      double value = 100.0;
      for ( int i = 0 ; i < 4000 ; i++ )
      {
         try
         {
            value = value + Math.random( ) - 0.5;
            series.add( current , new Double( value ) );
            current = ( Second ) current.next( );
         }
         catch ( SeriesException e ) 
         {
            System.err.println( "Error adding to series" );
         }
      }
      final XYDataset dataset=( XYDataset )new TimeSeriesCollection(series);
      JFreeChart timechart = ChartFactory.createTimeSeriesChart(
         "Computing Test", 
         "Seconds", 
         "Value", 
         dataset,
         false, 
         false, 
         false);
         
      int width = 560; /* Width of the image */
      int height = 370; /* Height of the image */ 
      File timeChart = new File( "TimeChart.jpeg" ); 
      ChartUtilities.saveChartAsJPEG( timeChart, timechart, width, height );
   }
}

Let us keep above Java code in TimeSeriesChart.java file, and then compile and run it from command prompt as follows :

$javac TimeSeriesChart.java 
$java TimeSeriesChart 

If everything is fine with your environment, it will compile and run to create JPEG image file TimeChart.jpeg file in your current directory.



Advertisements