如何根据频率值更改条形图颜色

Question

我已经生成了这张图表，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);

这是我现在用蓝色可视化它的图片：

这是我希望它看起来如何的示例：

我对jfreechart不是很熟悉，不知道有没有这种可能性。任何帮助将不胜感激。谢谢！

Answer 1

覆盖 XYBarRenderer, as suggested here. Use Color.getHSBColor() to generate the desired colors, as shown and here. Starting from this , the XYBarRenderer shown in this initial variation simply creates a static palette of blue shades having varying saturation. The updated version below dynamically scales the color saturation to reflect the dataset frequency values passed to the renderer's constructor, as shown 中的 getItemPaint()。

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 
 * @see 
 * @see 
 */
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);
    }
}

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