JFreeChart

Question

在 JFreeChart 中，我如何要求 RangeAxis 自动成为 'optimize' 本身？

现在我有一堆数据要显示在 25.00 到 27.00 之间，但是范围总是从 0 开始，这看起来不太好:

我尝试设置 plot.getRangeAxis().setAutoRange(true)，但它不起作用。当然，我可以计算我的最小值和最大值，然后我可以用 setRange(min, max) 设置它，但是有没有捆绑函数可以做到这一点？

转载：

import org.jfree.chart.ChartPanel;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.DefaultCategoryDataset;

public class LineChart_AWT extends ApplicationFrame {

    public LineChart_AWT( String applicationTitle , String chartTitle ) {
          super(applicationTitle);
          JFreeChart lineChart = ChartFactory.createLineChart(
             chartTitle,
             "Dates","Temperature",
             createDataset(),
             PlotOrientation.VERTICAL,
             true,true,false);

          CategoryPlot plot = (CategoryPlot) lineChart.getPlot();
          //plot.getRangeAxis().setRange(25, 27);
          //plot.getRangeAxis().setAutoRange(true);

          ChartPanel chartPanel = new ChartPanel( lineChart );
          chartPanel.setPreferredSize( new java.awt.Dimension( 560 , 367 ) );
          setContentPane( chartPanel );
       }

       private DefaultCategoryDataset createDataset( ) {
          DefaultCategoryDataset dataset = new DefaultCategoryDataset( );

          dataset.addValue( 26.44,"Temperature","2019-08-18 00:00");
          dataset.addValue( 26.2,"Temperature","2019-08-18 01:00");
          dataset.addValue( 25.93,"Temperature","2019-08-18 02:00");
          dataset.addValue( 25.71,"Temperature","2019-08-18 03:00");
          dataset.addValue( 25.54,"Temperature","2019-08-18 04:00");
          dataset.addValue( 25.42,"Temperature","2019-08-18 05:00");
          dataset.addValue( 25.25,"Temperature","2019-08-18 06:00");
          dataset.addValue( 25.19,"Temperature","2019-08-18 07:00");
          dataset.addValue( 25.25,"Temperature","2019-08-18 08:00");
          dataset.addValue( 25.36,"Temperature","2019-08-18 09:00");
          dataset.addValue( 25.52,"Temperature","2019-08-18 10:00");
          dataset.addValue( 25.86,"Temperature","2019-08-18 11:00");
          dataset.addValue( 26.51,"Temperature","2019-08-18 12:00");
          dataset.addValue( 26.82,"Temperature","2019-08-18 13:00");


          return dataset;
       }

       public static void main( String[ ] args ) {
          LineChart_AWT chart = new LineChart_AWT(
             "X-axis demo" ,
             "Y-range is wrong");

          chart.pack( );
          RefineryUtilities.centerFrameOnScreen( chart );
          chart.setVisible( true );
       }
    }

Answer 1

此外，必须用NumberAxis#setAutoRangeIncludesZero指定显示区间是否包含零值：

plot.getRangeAxis().setAutoRange(true);                            // uncomment
((NumberAxis)plot.getRangeAxis()).setAutoRangeIncludesZero(false); // add

结果：

JFreeChart - RangeAxis 自动调整范围并且不从 0 开始

JFreeChart - RangeAxis autorange and don't start from 0

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