JFreeChart Scatter Plot Lines

Question

I'm trying to create a graph with JFreeChart, however it doesn't get the lines right. Instead of connecting the points in the order I put them, it connects the points from in order of their x-values. I'm using ChartFactory.createScatterPlot to create the plot and a XYLineAndShapeRenderer to set the lines visible.

/edit: sscce:

package test;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;
import org.jfree.ui.ApplicationFrame;

public class PlotTest {
    private XYSeriesCollection dataset;

    public static void main (String[] args) {
        new PlotTest();
    }

    public PlotTest () {
        dataset = new XYSeriesCollection();
        XYSeries data = new XYSeries("data");
        data.add(3, 2); //Point 1
        data.add(1, 1); //Point 2
        data.add(4, 1); //Point 3
        data.add(2, 2); //Point 4
        dataset.addSeries(data);
        showGraph();
    }

    private void showGraph() {
        final JFreeChart chart = createChart(dataset);
        final ChartPanel chartPanel = new ChartPanel(chart);
        chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));
        final ApplicationFrame frame = new ApplicationFrame("Title");
        frame.setContentPane(chartPanel);
        frame.pack();
        frame.setVisible(true);
    }

    private JFreeChart createChart(final XYDataset dataset) {
        final JFreeChart chart = ChartFactory.createScatterPlot(
            "Title",                  // chart title
            "X",                      // x axis label
            "Y",                      // y axis label
            dataset,                  // data
            PlotOrientation.VERTICAL,
            true,                     // include legend
            true,                     // tooltips
            false                     // urls
        );
        XYPlot plot = (XYPlot) chart.getPlot();
        XYLineAndShapeRenderer renderer = new XYLineAndShapeRenderer();
        renderer.setSeriesLinesVisible(0, true);
        plot.setRenderer(renderer);
        return chart;
    }

}

Now I want the program to connect the dots in order 1-2-3-4, which is the order I added them to my dataset. But I do get them connected in order 2-4-1-3, sorted by x-value.

Answer 1

Try this:

 final XYSeries data = new XYSeries("data",false);

Using this constructor for XYSeries disables autosort, as defined in the XYSeries API.

Before:

After:

Answer 2

Absent an sscce it's hard to say, but you might try returning DomainOrder.NONE from your implementation of XYDataset. Also, it may help to know what meaning should be given to lines connecting dots in a scatter plot.