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If we have a column that is key that means we want to use that column as an independent variable and find the statistical values such as sum, mean, standard deviation, range, etc. for the dependent variable. This can be done with the combination of with and tapply function as shown in the below examples.Consider the below data frame −Example Live Demox1
To extract unique values in multiple columns in an R data frame, we first need to create a vector of the column values but for that we would need to read the columns in matrix form. After that we can simply unique function for the extraction. To understand how it works check out the below examples.Consider the below data frame −Example Live Demox1
The splitting of comma separated values in an R vector can be done by unlisting the elements of the vector then using strsplit function for splitting. For example, if we have a vector say x that contains comma separated values then the splitting of those values will be done by using the command unlist(strsplit(x,",")).Example Live Demox1
The na.omit performs any calculation by considering the NA values but do not include them in the calculation, on the other hand, na.rm remove the NA values and then perform any calculation. For example, if a vector has one NA and 5 values in total then their sum using na.omit will be calculated by excluding NA and by using na.rm it will be calculated by removing NA.Consider the below data frame −Example Live Demox1
Performing Wilcoxon test for all columns in an R data frame means that we want to use this test for single samples and the Wilcoxon test for single sample is used to test for the median of the sample, whether the median is equal to something or not. And if we do not provide any value then zero is the reference value. To perform Wilcoxon test for all columns can be done with the help of apply function and wilcox.test as shown in the below example.Consider the below data frame −Example Live Demox1
When we create a plot in base R the Y-axis values are generated automatically and mostly zero is now shown except in few cases that can’t be defined in particular but happens when there exists a zero in data. Therefore, if we want to include a zero with tick in base R plot then ylim argument can be used with the plot function.Exampleplot(5,ylim=c(0,5))OutputExampleplot(rnorm(100),ylim=c(-5,5))OutputExampleplot(rpois(10,2),ylim=c(0,10))Output
A list in R can contain many types of elements such as vector, data frame, matrices, etc. Sometimes the order of these elements matter, especially in situations when we have large size elements because it is difficult to view large size elements of a list. This ordering can be done with the help of single square bracket and combine operator c as shown in the below examples.Example Live DemoList1
Java provides certain classes called wrapper classes in the java.lang package. The objects of these classes wrap primitive datatypes within them.Using wrapper classes, you can also add primitive datatypes to various Collection objects such as ArrayList, HashMap etc. You can also pass primitive values over network using wrapper classes.ExampleLive Demoimport java.util.Scanner; public class WrapperExample { public static void main(String args[]){ Scanner sc = new Scanner(System.in); System.out.println("Enter an integer value: "); int i = sc.nextInt(); //Wrapper class of an integer Integer obj ... Read More
An interface in Java is similar to class but, it contains only abstract methods and fields which are final and static.Just like classes you can extend one interface from another using the extends keyword. You can also extend multiple interfaces from an interface using the extends keyword, by separating the interfaces using comma (, ) as −interface MyInterface extends ArithmeticCalculations, MathCalculations{ExampleFollowing is the Java program demonstrating, how to extend multiple interfaces from a single interface.interface ArithmeticCalculations{ public abstract int addition(int a, int b); public abstract int subtraction(int a, int b); } interface MathCalculations { public abstract double ... Read More
To match a regular expression with the given string You need to:.Compile the regular expression of the compile() method of the Pattern class.Get the Matcher object bypassing the required input string as a parameter to the matcher() method of the Pattern class.The matches() method of the Matcher class returns true if a match occurs else it returns false. Therefore, invoke this method to validate the data.ExampleFollowing is a Java regular expression example matches only dateLive Demoimport java.util.ArrayList; import java.util.List; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Sample { public static void main(String args[]){ //Creating the list to ... Read More