如何根据频率值更改条形图颜色

Question

我已经生成了这个图表，但我不知道如何根据频率创建色标

chart=ChartFactory.createXYBarChart(plotTitle,xaxis , true, yaxis, dataset);


plot = chart.getXYPlot();
    plot.getRangeAxis().setLabel("");
            plot.getDomainAxis().setLabel("");
            ValueAxis y_axis = plot.getRangeAxis();     // Y
            ValueAxis x_axis = plot.getDomainAxis();
            Font font = new Font("Veranda", Font.PLAIN, 12);
                y_axis.setTickLabelFont(font);
                x_axis.setTickLabelFont(font);
                x_axis.setTickLabelPaint(Color.black);
                y_axis.setTickLabelPaint(Color.black);
    plot.getDomainAxis().setAxisLineVisible(false);

    XYBarRenderer barRndr = (XYBarRenderer) plot.getRenderer();
    barRndr.setBarPainter(new StandardXYBarPainter());
    barRndr.setSeriesPaint(0, Color.blue);

这是我现在如何用蓝色可视化它的图片：

这是我希望它看起来如何的一个例子：

我对 jfreechart 不是很熟悉，所以我不知道是否有这样的可能性。 任何帮助将不胜感激。 谢谢！

Answer 1

覆盖getItemPaint()在你的XYBarRenderer ，如建议在这里。 使用Color.getHSBColor()生成所需的颜色，如此处和此处所示。 从这个例子开始，这个初始变体中显示的XYBarRenderer只是创建了一个具有不同饱和度的蓝色阴影的静态调色板。 下面的更新版本动态调整色彩饱和度，以反映传递给渲染器的构造函数中的数据集的频率值，如图所示这里。

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Paint;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.DateAxis;
import org.jfree.chart.axis.DateTickMarkPosition;
import org.jfree.chart.axis.DateTickUnit;
import org.jfree.chart.axis.DateTickUnitType;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.StandardXYBarPainter;
import org.jfree.chart.renderer.xy.XYBarRenderer;
import org.jfree.data.Range;
import org.jfree.data.general.DatasetUtils;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.time.Year;
import org.jfree.data.xy.IntervalXYDataset;

/**
 * @see https://stackoverflow.com/a/54680803/230513
 * @see https://stackoverflow.com/a/54362133/230513
 * @see https://stackoverflow.com/a/42612723/230513
 */
public class Test {

    private static final int N = 5;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Test()::display);
    }

    private void display() {
        JFrame f = new JFrame("Data");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        IntervalXYDataset dataset = createDataset();
        JFreeChart chart = ChartFactory.createXYBarChart("Data", "Time", true,
            "Value", dataset, PlotOrientation.VERTICAL, false, false, false);
        XYPlot plot = chart.getXYPlot();
        XYBarRenderer r = new MyXYBarRenderer(dataset);
        r.setDrawBarOutline(true);
        r.setBarPainter(new StandardXYBarPainter());
        plot.setRenderer(r);
        f.add(createPanel(chart));
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private class MyXYBarRenderer extends XYBarRenderer {

        private final IntervalXYDataset dataset;

        public MyXYBarRenderer(IntervalXYDataset dataset) {
            this.dataset = dataset;
        }

        @Override
        public Paint getItemPaint(int row, int col) {
            double value = dataset.getYValue(row, col);
            Range r = DatasetUtils.findRangeBounds(dataset);
            double range = r.getUpperBound() - r.getLowerBound() + 1;
            float scaled = (float) (value / range);
            return Color.getHSBColor(2f / 3, 1 - scaled, 1);
        }
    }

    private ChartPanel createPanel(JFreeChart chart) {
        final XYPlot plot = chart.getXYPlot();
        final DateAxis domainAxis = (DateAxis) plot.getDomainAxis();
        domainAxis.setTickUnit(new DateTickUnit(DateTickUnitType.YEAR, 1));
        domainAxis.setTickMarkPosition(DateTickMarkPosition.MIDDLE);
        domainAxis.setDateFormatOverride(new SimpleDateFormat("yyyy"));
        return new ChartPanel(chart) {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(500, 250);
            }
        };
    }

    private IntervalXYDataset createDataset() {
        TimeSeries series = new TimeSeries("Value");
        Calendar c = Calendar.getInstance();
        for (int i = 0; i < N; i++) {
            series.add(new Year(c.getTime()), i + 1);
            c.add(Calendar.YEAR, 1);
        }
        for (int i = 1; i < N; i++) {
            series.add(new Year(c.getTime()), N - i);
            c.add(Calendar.YEAR, 1);
        }
        return new TimeSeriesCollection(series);
    }
}