数字轴 setTickUnit 包含指定数字

我使用 JFreeChart 显示正态分布，并将刻度数更改为标准差；但我也希望在刻度出现的中间始终存在“平均”值。交叉发布.

所以标准差 = 2 ；平均值 = 1

-3 -1  1 3 5

标准差 = 5 ；平均值 = 15

0 5 10 15 20 25 30

JFreeChart.java

public class JFreeChartPanel extends JPanel {
    private final XYPlot plot;
    double mean = 0.0, sd = 1.0;
    XYDataset dataset = initDataset();
    NumberAxis domain = new NumberAxis("Y") {
    @Override
    protected double calculateLowestVisibleTickValue() {
        double lowTickValue = super.calculateLowestVisibleTickValue();
        if (mean % 2 == 1) {
            return lowTickValue + 1;
        } else {
            return lowTickValue;
        }
    }
};
    public JFreeChartPanel(){
        JFreeChart chart = ChartFactory.createXYLineChart(
            "Normal Distribution",
            "X", 
            "PDF", 
            dataset,
            PlotOrientation.VERTICAL,
            false,
            false,
            false
        );
        plot=chart.getXYPlot();
        domain.setAutoRangeStickyZero(false);
        domain.setTickUnit(new NumberTickUnit(sd));
        plot.setDomainAxis(domain);
        final ChartPanel chartPanel = new ChartPanel(chart);
        setLayout(new BorderLayout());
        add(chartPanel);
    }

    private XYDataset initDataset() {
        double minX=mean-(4*sd),maxX=mean+(4*sd);
        Function2D normal = new NormalDistributionFunction2D(mean, sd);
        XYDataset dataset = DatasetUtilities.sampleFunction2D(normal, minX, maxX, 100, "Normal");
        return dataset;
    }

    public double getMean() {
        return mean;
    }

    public void setMean(double mean) {
       this.mean = mean;
       plot.setDataset(initDataset());
    }

    public double getSd() {
        return sd;
    }

    public void setSd(double sd) {
        this.sd = sd;
        domain.setTickUnit(new NumberTickUnit(sd));
        plot.setDataset(initDataset());
    }
}

UI.java

public class UI extends javax.swing.JFrame {

    public UI() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    private void initComponents() {
      Auto-generated Netbeans GUI COde
    }                     

    public void updateMean()
    {
        try{
            double m = Double.parseDouble(mean.getText());
            jFreeChartPanel.setMean(m);
        }catch(Exception e){
        }
    }
    public void updateSd()
    {
        try{
            double sd = Double.parseDouble(standardDeviation.getText());
            jFreeChartPanel.setSd(sd);
        }catch(Exception e){
        }
    }

    public static void main(String args[]) {
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Windows".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {

        }
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new UI().setVisible(true);
            }
        });
    }

    private javax.swing.JPanel inputPanel;
    private main.JFreeChartPanel jFreeChartPanel;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JToggleButton jToggleButton1;
    private javax.swing.JTextField mean;
    private javax.swing.JLabel meanLabel;
    private javax.swing.JTextField standardDeviation;
    private javax.swing.JLabel standardDeviationLabel;
}

从此开始example https://stackoverflow.com/a/40167139/230513，我根据您的修改进行了以下更改，以获得如下所示的 µ=15 和 σ=5 的结果：

import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.axis.NumberTickUnit;
…
private double mean = 15.0, sigma = 5.0;
…
private XYDataset initDataset() {
    double minX = mean - (3 * sigma), maxX = mean + (3 * sigma);
    Function2D normal = new NormalDistributionFunction2D(mean, sigma);
    XYDataset dataset = DatasetUtilities.sampleFunction2D(normal, minX, maxX, 100, "Normal");
    return dataset;
}
…
public JFreeChartPanel() {
    …
    plot = chart.getXYPlot();
    NumberAxis domain = (NumberAxis) plot.getDomainAxis();
    domain.setTickUnit(new NumberTickUnit(sigma));
    …
}

您的另一种情况，μ=1 和 σ=2，需要覆盖NumberAxis method calculateLowestVisibleTickValue()使刻度落在奇数上。

NumberAxis domain = new NumberAxis("Y") {
    @Override
    protected double calculateLowestVisibleTickValue() {
        double lowTickValue = super.calculateLowestVisibleTickValue();
        if (mean % 2 == 1) {
            return lowTickValue + 1;
        } else {
            return lowTickValue;
        }
    }
};
domain.setTickUnit(new NumberTickUnit(sigma));
plot = chart.getXYPlot();
plot.setDomainAxis(domain);

为什么图表对于平均值 3 和标准差 1 以及平均值 6 sd 2、平均值 9 sd 3 等都略有倾斜；这里有一个picture https://i.stack.imgur.com/PwzV8.jpg显示这个。

正如所讨论的，有一个“当自动确定范围时影响添加到轴范围的边距大小的标志。”

domain.setAutoRangeStickyZero(false);

我添加了...代码。

添加您的实例修订版6 https://stackoverflow.com/revisions/40184461/6 JFreeChartPanel to a JFrameµ=1 且 σ=2 产生以下结果：

这种情况发生在均值较高的情况下。

您可以从自动范围中排除零。

domain.setAutoRangeIncludesZero(false);