如何从数组中获取特定的值并输出平均值？

huangapple
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英文:

How to get specific values in an array and output an average?

问题

  1. import java.util.Scanner;
  2. import java.io.File;
  3. import java.util.ArrayList;
  5. public class AvgCalc {
  7.     public static void main(String[] args) {
  8.         
  9.         File myFile = new File("C:\\Users\\Byoma\\Downloads\\Assignment1.txt");
  10.         
  11.         try {
  12.             
  13.             Scanner myScanner = new Scanner(myFile);
  14.             
  15.             while (myScanner.hasNextLine()) {
  16.                 String line = myScanner.nextLine();
  17.                 
  18.                 String[] tokens = line.split(",");
  19.                 String name = tokens[0];
  20.                 
  21.                 double sum = 0.0;
  22.                 int count = 0;
  23.                 
  24.                 for (int i = 1; i < tokens.length; i++) {
  25.                     sum += Double.parseDouble(tokens[i]);
  26.                     count++;
  27.                 }
  28.                 
  29.                 double average = sum / count;
  30.                 
  31.                 System.out.println("Name: " + name + ", Average: " + average);
  32.             }
  33.             
  34.             myScanner.close();
  35.         }
  36.         
  37.         catch (Exception e) {
  38.             System.out.println("Error reading file: " + myFile.getAbsolutePath());
  39.         }
  40.     }
  41. }
英文:

I'm having trouble trying to figure out what exactly needs to be done in this scenario for the code to work properly. I need to output a text file containing a name and the average of a list of values on each line, the text files contains these things:

  1. Carol,35.00,67.00,13.00
  2. Steve,14.00,82.00,41.00,66.00
  3. Sharon,56.00,42.00,28.00,70.00
  4. Roy,80.00,105.00,55.00
  5. Beatrice,20.00

How do I output the average for each line in this scenario?
The code below is an example of a more simpler one with each line only containing one value, I just don't know how to modify the array list or the code to get the values I want.

  1.     import java.util.Scanner;
  2.     import java.io.File;
  3.     import java.util.ArrayList;
  5.     public class AvgCalc {
  7.     	public static void main(String[] args) {
  8.     		
  9.     		File myFile = new File(&quot;C:\\Users\\Byoma\\Downloads\\Assignment1.txt&quot;);
  10.     		
  11.     		try {
  12.     			
  13.     			Scanner myScanner = new Scanner(myFile);
  14.     			
  15.     			while (myScanner.hasNextLine()) {
  16.     				String line = myScanner.nextLine();
  17.     				
  18.     				String[] tokens = line.split(&quot;,&quot;);
  19.     				String name = tokens[0];
  20.     				String average = tokens [1];
  21.     				System.out.println(&quot;Name: &quot; + name + &quot;, Average: &quot; + average);
  22.     			}
  23.     			
  24.     			myScanner.close();
  25.     		}
  26.     		
  27.     		catch (Exception e) {
  28.     			System.out.println(&quot;Error reading file: &quot; + myFile.getAbsolutePath());
  29.     		}
  30.     	}
  31.     }

答案1

得分: 1

假设你列出的每个示例中的人名都位于文本文件中的单独一行，将以下代码插入到你现有的代码中，并做出少量修改，就能解决这个问题。

  1. import java.util.Scanner;
  2. import java.io.File;
  3. import java.util.ArrayList;
  5. public class test {
  7.     public static void main(String[] args) {
  9.         File myFile = new File("C:\\Users\\Byoma\\Downloads\\Assignment1.txt");
  11.         try {
  13.             Scanner myScanner = new Scanner(myFile);
  15.             while (myScanner.hasNextLine()) {
  16.                 String line = myScanner.nextLine();
  18.                 String[] tokens = line.split(",");
  19.                 String name = tokens[0];
  20.                 double sum = 0; // 初始化一个 double 变量来求和
  21.                 for (int i = 1; i < tokens.length; i++) {
  22.                     sum += Double.parseDouble(tokens[i]); // 将文本文档中的值解析为 double
  23.                 }
  24.                 double average = sum / (tokens.length - 1); // 通过将总和除以值的数量来计算平均值
  25.                 System.out.println("姓名：" + name + "，平均值：" + average);
  26.             }
  28.             myScanner.close();
  29.         }
  31.         catch (Exception e) {
  32.             System.out.println("读取文件出错：" + myFile.getAbsolutePath());
  33.         }
  34.     }
  35. }

注意：以上是你要求的代码的翻译部分，没有包括其他内容。

英文:

Assuming that each of the people that you listed for an example is on a separate line in the text file, adding a for loop to your current code and changing a few lines will solve this for you.

  1. import java.util.Scanner;
  2. import java.io.File;
  3. import java.util.ArrayList;
  5. public class test {
  7.     public static void main(String[] args) {
  9.         File myFile = new File(&quot;C:\\Users\\Byoma\\Downloads\\Assignment1.txt&quot;);
  11.         try {
  13.             Scanner myScanner = new Scanner(myFile);
  15.             while (myScanner.hasNextLine()) {
  16.                 String line = myScanner.nextLine();
  18.                 String[] tokens = line.split(&quot;,&quot;);
  19.                 String name = tokens[0];
  20.                 double sum = 0; //Initialized a double to sum the values
  21.                 for (int i = 1; i &lt; tokens.length; i++) {
  22.                     sum += Double.parseDouble(tokens[i]); //Parse the values in the text document as doubles
  23.                 }
  24.                 double average = sum / (tokens.length - 1); //Get the average by dividing the sum by the number of values
  25.                 System.out.println(&quot;Name: &quot; + name + &quot;, Average: &quot; + average);
  26.             }
  28.             myScanner.close();
  29.         }
  31.         catch (Exception e) {
  32.             System.out.println(&quot;Error reading file: &quot; + myFile.getAbsolutePath());
  33.         }
  34.     }
  35. }

答案2

得分: 0

你从数组的第一个元素开始迭代，累加它们，然后将所有元素的总和除以元素的数量（请注意，我在累加总和时使用了int，但如果输入不是整数值，你可以使用floats或doubles，而且你不严格需要count变量）：

  1. public class MyClass {
  2.     public static void main(String args[]) {
  3.         String[] array = {"Name", "11", "5", "107"};
  4.         int accumulated = 0; // 这将保存所有数字的总和
  5.         int count = 0; // 我们用这个来跟踪有多少个数字
  6.         for (int i = 1; i < array.length; i++) {
  7.             // 添加数字，我们将它们转换为int，因为它们是字符串
  8.             accumulated = accumulated + Integer.parseInt(array[i]); 
  9.             count++;
  10.         }  
  11.         System.out.println("总和: "+accumulated);
  12.         System.out.println("元素数量: "+count);
  13.         float average = accumulated/count;
  14.         System.out.println("平均值: "+average);
  15.     }
  16. }

输出：

  1. 总和: 123
  2. 元素数量: 3
  3. 平均值: 41.0
英文:

You iterate through the elements of the array starting with element 1 and accumulate them, then divide the total sum of the elements by the number of elements (note that I used int for the accumulated sum, but you can use floats or doubles if your input is not integer values, and that you don't strictly need the count variable):

  1. public class MyClass {
  2.     public static void main(String args[]) {
  3.         String[] array = {&quot;Name&quot;, &quot;11&quot;, &quot;5&quot;, &quot;107&quot;};
  4.         int accumulated = 0; //this will hold the sum of all the numbers
  5.         int count = 0; //we use this to keep track of how many numbers we have
  6.         for (int i = 1; i &lt; array.length; i++) {
  7.             //add the numbers, we convert them to int since they are strings
  8.             accumulated = accumulated + Integer.parseInt(array[i]); 
  9.             count++;
  10.         }  
  11.         System.out.println(&quot;Total sum: &quot;+accumulated);
  12.         System.out.println(&quot;Number of elements: &quot;+count);
  13.         float average = accumulated/count;
  14.         System.out.println(&quot;Average: &quot;+average);
  15.     }
  16. }

Output:

  1. Total sum: 123
  2. Number of elements: 3
  3. Average: 41.0

huangapple
  • 本文由 发表于 2020年8月24日 06:05:05
  • 转载请务必保留本文链接：https://go.coder-hub.com/63552451.html
  • arrays
  • java
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