Question

我有一个双重2-D矩阵，它包含负和正浮点值以及NA。这些值属于图像数据。值位于-0.4到+0.4范围内我想使用JFreeChart库创建直方图并查看bin宽度为0.05的频率。为了将数据集矩阵准备为HistogramDataset，我首先将矩阵转换为1-D双矩阵（下面的代码），然后使用chartFactory类中可用的createHistogram方法绘制直方图。但是，我没有得到结果。我可以在chartPanel区域看到一条垂直线。我查看了这些示例，但他们没有使用像数据这样的二维矩阵作为输入。

http://www.java2s.com/Code/Java/Chart/JFreeChartXYSeriesDemo3.htm

Image histogram generated by JFreeChart

第二个例子有点类似，但它没有使用二维矩阵。

这是我为准备数据集和创建直方图而实施的代码。

import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.statistics.HistogramDataset;
import org.jfree.data.statistics.HistogramType;

import java.awt.*;

public class Histogram {

    public JFreeChart createHistogram(double[][] doubleMatrix){

        // Generate a one dimensional array of the size w*h of the double matrix
        double[] data = new double[doubleMatrix.length * doubleMatrix[0].length];
        int count = 0;

        for (int i=0; i<doubleMatrix.length; i++) {
            for (int j = 0; j < doubleMatrix[i].length; j++) {
                data[count] = doubleMatrix[i][j];
                count++;
            }
        }

       // int number = data.length;
        HistogramDataset dataset = new HistogramDataset();
        dataset.setType(HistogramType.FREQUENCY);
        dataset.addSeries("Hist",data,50); // Number of bins is 50
        String plotTitle = "";
        String xAxis = "Frequency";
        String yAxis = "Mass Error (Da)";
        PlotOrientation orientation = PlotOrientation.VERTICAL;

        boolean show = false;
        boolean toolTips = false;
        boolean urls = false;
        JFreeChart chart = ChartFactory.createHistogram(plotTitle, xAxis, yAxis,
                dataset, orientation, show, toolTips, urls);

        chart.setBackgroundPaint(Color.white);

        return chart;
    }
}

我正在使用的二维双矩阵可以在这里找到：http://www.filedropper.com/data_4

我使用上述代码获得的数据集是以下直方图（！）。它是直方图的大小，不适合ChartPanel或JPanel吗？

Answer 1

我找到了解决方案。我首先使用ArrayList从双矩阵中删除所有NA，然后将此arrayList转换为1D数组，然后生成直方图。它现在有效。这是代码：

import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.statistics.HistogramDataset;
import org.jfree.data.statistics.HistogramType;

import java.awt.*;
import java.util.ArrayList;

public class Histogram {

    public JFreeChart createHistogram(double[][] doubleMatrix){

        // Generate a one dimensional array of the size w*h of the double matrix
        ArrayList<Double> dataArrayList = new ArrayList<Double>();

        for (int i=0; i<doubleMatrix.length; i++) {
            for (int j = 0; j < doubleMatrix[i].length; j++) {
                double value =  doubleMatrix[i][j];
                if( Double.isNaN(value))
                    continue;
                else
                    dataArrayList.add(value);
                    System.out.println(value);
            }
        }

        double[] data = new double[dataArrayList.size()];

        for(int p = 0; p < dataArrayList.size();p++)
             data[p] = dataArrayList.get(p);


       // int number = data.length;
        HistogramDataset dataset = new HistogramDataset();
        dataset.setType(HistogramType.RELATIVE_FREQUENCY);
        dataset.addSeries("Hist",data,200); // Number of bins is 50
        String plotTitle = "";
        String xAxis = "Frequency";
        String yAxis = "Mass Error (Da)";
        PlotOrientation orientation = PlotOrientation.VERTICAL;

        boolean show = false;
        boolean toolTips = false;
        boolean urls = false;
        JFreeChart chart = ChartFactory.createHistogram(plotTitle, xAxis, yAxis,
                dataset, orientation, show, toolTips, urls);

        chart.setBackgroundPaint(Color.white);

        return chart;
    }
}

如何准备数据集以使用JFreeChart以直方图的形式显示？

1 个答案: