How to Calculate Standard Deviation by Java Program
Java Array and Methods.
- An object of a class that is dynamically produced in Java is an array. Java array implements the Serializable and Cloneable interfaces and derives from the Object class. The first element of an array is stored at index 0, the second member is kept at index 1, and so forth. Arrays in Java are index-based.
- A method in Java is a section of code that completes a certain task. Code can be contained in methods, which makes it more reusable and understandable.Java methods make it simpler to build and maintain complicated programmes by giving coders a means to organise and reuse code.
To know more about Java Program to calculate Standard Deviation read the complete article.
Steps to Calculate Standard Deviation by Java Program
Here are the steps to calculate the standard deviation in Java:
First, you need to find the mean (average) of the data set.
Then, subtract the mean from each data point to find the deviations.
Square each deviation to remove the negative sign.
Find the sum of all the squared deviations.
Divide the sum by the number of data points minus one (n-1).
- Take the square root of the result to find the standard deviation.
Java Array :
CODE OPTIMIZATION: Java arrays are simple to read and edit because they are kept in memory as continuous chunks. By lowering the amount of memory operations needed to access elements and the time required to complete these operations, this can aid in code optimization.
Random Access: Java arrays allow for random access of elements, meaning that any element can be accessed directly by its index without having to traverse the entire array. This can help to optimize code by reducing the amount of time needed to find an element in the array, especially for large arrays.
CODE OPTIMIZATION: Java arrays are simple to read and edit because they are kept in memory as continuous chunks. By lowering the amount of memory operations needed to access elements and the time required to complete these operations, this can aid in code optimization.
Random Access: Java arrays allow for random access of elements, meaning that any element can be accessed directly by its index without having to traverse the entire array. This can help to optimize code by reducing the amount of time needed to find an element in the array, especially for large arrays.
Java Methods :
Methods allow you to hide the implementation details of a task, making it easier to change the underlying code without affecting the rest of the program. This can help to reduce the risk of introducing bugs into your code and make it easier to maintain in the long term.
Let’s look at a Java Program to calculate Standard Deviation to perform certain operations.
Example 1: Java Program to Calculate standard Deviation.
Run
import java.util.Arrays;
public class Main {
public static void main(String[] args) {
double[] input = {10, 20, 35, 40, 45};
double sum = 0, mean;
int n = input.length;
for (int i = 0; i < n; i++) {
sum += input[i];
}
mean = sum / n;
System.out.println("Mean: " + mean);
sum = 0;
for (int i = 0; i < n; i++) {
sum += Math.pow(input[i] - mean, 2);
}
mean = sum / (n - 1);
double deviation = Math.sqrt(mean);
System.out.println("Standard deviation: " + deviation);
}
}
Output
Mean: 15.0 Standard deviation: 7.0710678118654755
Explanation:
- This code is a Java program that calculates the mean and standard deviation of an array of 5 values (5, 10, 15, 20, 25).
- The mean is calculated by adding all the elements in the array and dividing by the number of elements. The standard deviation is calculated by finding the variance, which is the average of the squared differences between each element and the mean, and then taking the square root of the variance.
- The results are printed on the console in the format "Mean: [mean value]" and "Standard deviation: [standard deviation value]".
Example 2 : Java Program to Calculate Standard Deviation
Run
class Main
{
public static void main(String args[])
{
double[] input={5,10,15,20,25};
double n=5,sum=0,mean;
for(int i=0;i<n;i++)
{
sum=sum+input[i];
}
mean=sum/n;
System.out.println("Mean :"+mean);
sum=0;
for(int i=0;i<n;i++)
{
sum+=Math.pow((input[i]-mean),2);
}
mean=sum/(n-1);
double deviation=Math.sqrt(mean);
System.out.println("standard deviation :"+deviation);
}
}
Output
Mean :15.0 standard deviation :7.905694150420948
Explanation:
This Java programme computes an array of 5 variables' mean and standard deviation (5, 10, 15, 20, 25). The array's total elements are added, and the mean is obtained by dividing by the array's total elements. Finding the variance—the average of the squared deviations between each element and the mean—and then calculating its square root yields the standard deviation. The result is displayed as "Mean:15.0" and "standard deviation:7.0710678118654755" on the console.
Example 3: Java Program to Calculate Standard Deviation:
Run
import java.util.Arrays;
public class Main {
public static double calculateSD(double numArray[]) {
double sum = 0.0, standardDeviation = 0.0;
int length = numArray.length;
for (double num : numArray) {
sum += num;
}
double mean = sum / length;
for (double num : numArray) {
standardDeviation += Math.pow(num - mean, 2);
}
return Math.sqrt(standardDeviation / length);
}
public static void main(String[] args) {
double[] numArray = {1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
System.out.format("Standard Deviation = %.6f", calculateSD(numArray));
}
}
Output
Standard Deviation = 2.581989
Explanation:
The compute SD method in this programme receives an array of values as input and outputs the standard deviation. The following steps are used to compute the standard deviation:
Calculate the mean of the numbers
Subtract the mean from each number to get the variance
Calculate the square root of the variance to get the standard deviation.
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