[英]Calculating mean and standard deviation in java
我在计算平均值时没有问题,但是我的标准偏差一直存在。 我很沮丧 对于标准偏差,我使用for循环返回填充有用户提示值的数组,并从每个值中减去平均值,然后求平方。 然后再用一个for循环将它们加在一起,除以值的数量,然后将其平方根。 我怎么了?
import java.util.Scanner;
public class Assignment4
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Please enter the number of items:"); // PROMPTS USER FOR # OF ITEMS
double size = scan.nextDouble();
double meanSum = 0;
double deviationSum = 0;
double array[] = new double [(int) size];
System.out.println("Please enter the items");
for (int i = 0; i < size; i++)
{
array[i]= scan.nextDouble();
}
for (int i = 0; i < size; i++)
{
meanSum += array[i];
}
double mean = ((meanSum / size));
System.out.println("The mean is: " + mean);
//STANDARD DEVIATION CALCULATION
for (int i = 0; i < size; i++)
{
array[i] = (Math.pow((array[i] - mean), 2));
}
for (int i = 0; i < size; i++)
{
deviationSum += array[i];
}
double variance = ((deviationSum / size));
double standardDeviation = Math.sqrt(variance);
System.out.println("The standard deviation is: " + standardDeviation);
}
}
您可以将答案与DescriptiveStatistics输出的内容进行比较( https://commons.apache.org/proper/commons-math/javadocs/api-2.2/org/apache/commons/math/stat/descriptive/DescriptiveStatistics.html )
您只需调用.addValue(double)
函数,最后调用该函数以返回均值和标准差
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