使用JFreeChart为两个系列设置不同的y轴

Question

我使用JFreeChart使用折线图绘制两个系列的数据（XYSeries）。复杂的因素是，其中一个数据系列的y值通常远高于我的第二个数据系列中的y值（假设第一个系列具有数百万数量级的y值，而第二个系列具有数百数量级的y值）。在我的第一个数据集中高值的存在导致绘图的范围使得我的第二个数据集的y值不再是可理解的。

在绘图中添加第二个y轴，这样我的两个数据系列都使用自己的y轴，就可以解决这个问题。有人知道如何使用JFreeChart吗？

完整性的当前代码：

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());

Answer 1

您可以手动创建JFreeChart对象，而不是使用ChartFactory。首先生成数据集和Plot，将每个数据集设置为索引。然后，可以使用必要的轴和渲染器自定义"打印"。以下是一个使用伪数据进行此操作的示例，该伪数据有两个数据集，每个数据集的y值大小不同：

    //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);

Answer 2

我已经调整了上面的解决方案，以使用最新版本的JFreeChart（2019-Jan-29）。

如果JFreeChart库被正确导入，这将正确运行。我有一个pom.xml设置了这样的导入

 <dependency>
        <groupId>org.jfree</groupId>
        <artifactId>jfreechart</artifactId>
        <version>1.0.19</version>
 </dependency>

以下是完整的代码片段：

import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYSplineRenderer;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;
import javax.swing.*;
import java.awt.*;
class GraphTest2 {
    // driver that actually runs the thing
    public static void main(String[] args) {
        SwingUtilities.invokeLater( () -> {
            LineChartEx ex = new LineChartEx();
            ex.setVisible(true);
        });
    }
}
class LineChartEx extends JFrame {
    public LineChartEx() {
        initUI();
    }
    private void initUI() {
        //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 jpanel = new ChartPanel(chart);

        // NEW PART THAT MAKES IT WORK
        ChartPanel chartPanel = new ChartPanel(chart);
        chartPanel.setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15));
        chartPanel.setBackground(Color.white);
        add(chartPanel);
        pack();
        setTitle("Line chart");
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }