Question

我有一个名为numbers.txt的文本文件，里面有很多数字。我需要找到数字的平均中位数和众数。我可以读取文件，但是我不知道更多。

import java.io.File;
import java.util.Scanner;
public class Terms {


    public static void main(String[] args)throws Exception {

        File file = 
      new File("C:\\Users\\coderva.org\\Documents\\numbers.txt");
    Scanner sc = new Scanner(file);

    while (sc.hasNextLine()) 
      System.out.println(sc.nextLine());  



}
}

Answer 1

您可以这样创建数字列表：

List<Integer> numberList = new ArrayList<>();
while (sc.hasNextInt()) 
  numberList.add(sc.nextInt());

或者当您有双打或浮空时：

List<Double> numberList = new ArrayList<>();
while (sc.hasNextDouble()) 
  numberList.add(sc.nextDouble()); 

List<Float> numberList = new ArrayList<>();
while (sc.hasNextFloat()) 
  numberList.add(sc.nextFloat());

从那里可以计算出平均值，如下所示：

sum = numberList.stream().mapToInt(Integer::intValue).sum();
average = sum / numberList.size();

对于所需的其他属性，依此类推。

注意：求和类型和平均值取决于您从文件中读取的类型。

Answer 2

根据均值，中位数和众数的定义：

public static void main(String[] args) {
    File file = new File("C:\\Users\\coderva.org\\Documents\\numbers.txt");

    Scanner sc = null;

    try {
        sc = new Scanner(file);
    } catch (FileNotFoundException e) {
        System.out.println("File not found");
        e.printStackTrace();
        return;
    }

    ArrayList<Float> list = new ArrayList<Float>();

    while (sc.hasNextFloat())
        list.add(sc.nextFloat());

    int size = list.size();

    if (size == 0) {
        System.out.println("Empty list");
        return;
    }

    Collections.sort(list);

    for (int i = 0; i < size; i++) {
        System.out.print(list.get(i) + " ");
    }

    System.out.println();

    // mean value, classical way
    float sum = 0;
    for (float x : list) {
        sum += x;
    }

    float mean = sum / size; // mean as integer

    //median
    float median;

    if (size % 2 == 0) {
        float x1 = list.get(size / 2 - 1);
        float x2 = list.get(size / 2);
        median = (x1 + x2) / 2;
    } else {
        median = list.get(size / 2);
    }

    //mode
    Float mode = null;
    int counter = 1;
    for (int i = 0; i < size; i++) {
        int freq = Collections.frequency(list, list.get(i));
        if (freq > counter) {
            mode = list.get(i);
            counter = freq;
        }
    }

    System.out.println("Mean=" + mean);

    System.out.println("Median=" + median);

    if (mode == null) {
        System.out.println("No mode found");
    } else {
        System.out.println("Mode=" + mode);
    }
}

从文本文件Java查找平均中位数模式

2 个答案: