如何计算阵列的中值？ [英] How to calculate the median of an array?

问题描述

我试图计算总，平均和由一个文本框接收的输入填充的数组这就是中位数。我已经成功地制定出总的和平均的，我只是不能位数工作。我认为阵列需要进行排序，我可以做到这一点之前，但我不知道如何做到这一点。这就是问题所在，还是有另外一个，我没有找到？这里是我的code：

 进口java.applet.Applet中;
进口java.awt.Graphics;
进口java.awt中的*。
java.awt.event中导入*。whileloopq扩展Applet的公共类实现的ActionListener
{
    标签标签;
    文本字段输入;
    INT NUM;
    INT指数;
    INT [] numArray =新INT [20];
    INT总和;
    INT总;
    双重魅力;
    INT位;    公共无效的init（）
    {
        标签=新标签（输入数字）;
        输入=新的TextField（5）;
        添加（标签）;
        添加（输入）;
        input.addActionListener（本）;
        索引= 0;
    }    公共无效的actionPerformed（ActionEvent的EV）
    {
        INT NUM =的Integer.parseInt（input.getText（））;
        numArray [指数] = NUM​​;
        指数++;
        如果（指数== 20）
        input.setEnabled（假）;
            input.setText（）;
        总和= 0;
        的for（int i = 0; I＆LT; numArray.length;我++）
        {
            总和+ = numArray [I]
        }
        总= SUM;
        平均=总/指数;        中位数= numArray [numArray.length / 2];        重绘（）;    }    公共无效漆（图形格拉夫）
    {        graf.drawString（总=+ Integer.toString（总），25，85）;
        graf.drawString（平均值=+ Double.toString（平均），25，100）;
        graf.drawString（中位数=+ Integer.toString（中位数），25，115）;    }
}
 

解决方案

在Java中Arrays类有一个静态的排序功能，您可以用 Arrays.sort（numArray）调用。

  Arrays.sort（numArray）;
双位数;
如果（numArray.length％2 == 0）
    中位数=（（双）numArray [numArray.length / 2] +（双）numArray [numArray.length / 2  -  1]）/ 2;
其他
    中位数=（双）numArray [numArray.length / 2];
 

I'm trying to calculate the total, mean and median of an array thats populated by input received by a textfield. I've managed to work out the total and the mean, I just can't get the median to work. I think the array needs to be sorted before I can do this, but I'm not sure how to do this. Is this the problem, or is there another one that I didn't find? Here is my code:

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.*;
import java.awt.event.*;

public class whileloopq extends Applet implements ActionListener
{
    Label label;
    TextField input;
    int num;
    int index;
    int[] numArray = new int[20];
    int sum;
    int total;
    double avg;
    int median;



    public void init ()
    {
        label = new Label("Enter numbers");
        input = new TextField(5);
        add(label);
        add(input);
        input.addActionListener(this);
        index = 0;
    }

    public void actionPerformed (ActionEvent ev)
    {
        int num = Integer.parseInt(input.getText());
        numArray[index] = num;
        index++;
        if (index == 20)
        input.setEnabled(false);
            input.setText("");
        sum = 0;
        for (int i = 0; i < numArray.length; i++)
        {
            sum += numArray[i];
        }
        total = sum;
        avg = total / index;

        median = numArray[numArray.length/2];



        repaint();

    }



    public void paint (Graphics graf)
    {



        graf.drawString("Total   = " + Integer.toString(total), 25, 85);
        graf.drawString("Average = " + Double.toString(avg), 25, 100);
        graf.drawString("Median = " + Integer.toString(median), 25, 115);



    }
}

解决方案

The Arrays class in Java has a static sort function, which you can invoke with Arrays.sort(numArray).

Arrays.sort(numArray);
double median;
if (numArray.length % 2 == 0)
    median = ((double)numArray[numArray.length/2] + (double)numArray[numArray.length/2 - 1])/2;
else
    median = (double) numArray[numArray.length/2];

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