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To find the row products for each row in an R data frame, we can use rowProds function of matrixStats package but we need to read the data frame as a matrix.For Example, if we have a data frame called df then we can find the row products for each row in df by using the command given below −rowProds(as.matrix(df))Example 1Following snippet creates a sample data frame −x1
Kotlin is based on Java, hence we can use Java-based library functions to delay a function call. In this article, we will be using a Java library function to delay the function call using Timer() and schedule().Exampleimport java.util.Timer import kotlin.concurrent.schedule fun main(args: Array) { // Execution starting point println("Hello world!!") // Delay of 5 sec Timer().schedule(5000){ //calling a function newMethod() } } fun newMethod(){ println("Delayed method call!") }OutputOnce executed, the above piece of code will yield the following output −Hello world!! Delayed method call!
String is a collection which is implemented using String class. As per the Kotlin documentation, a string can be defined as follows −Class String : Comparable, CharSequenceIn Kotlin, a string is a collection of characters. Strings are immutable in nature which means they are read-only. The length and elements of a string can be modified once declared.In Java, we have an option to create an empty String array by defining it like String[]. In this article, we will see how we can achieve the same using Kotlin library function.Example: Using arrayOf()Kotlin library provides a function to create an array of ... Read More
Kotlin provides multiple ways to generate a random number. In this article, we will see different ways to generate a random number and access it throughout the program.Example – Using Random classRandom() is an abstract class which generates random numbers with the given conditions. It can be accessed after importing Kotlin.random.Random.As per the Kotlin documentation, the companion object Random.Default is the default instance of Random class. In the following example, we will generate a list of random values with int (1-30) .Exampleimport kotlin.random.Random fun main() { val myRandomValues = List(5) { Random.nextInt(0, 30) } // Prints ... Read More
Sometimes it becomes necessary to access the index of an array. In this article, we will see how we can access the index of an array in Kotlin while using forEach loop.Example: Using forEachIndexed()nstead of using forEach() loop, you can use the forEachIndexed() loop in Kotlin. forEachIndexed is an inline function which takes an array as an input and its index and values are separately accessible.In the following example, we will traverse through the "Subject" array and we will print the index along with the value.Examplefun main() { var subject = listOf("Java", "Kotlin", "JS", "C") ... Read More
"reified" is a special type of keyword that helps Kotlin developers to access the information related to a class at runtime. "reified" can only be used with inline functions. When "reified" keyword is used, the compiler copies the function’s bytecode to every section of the code where the function has been called. In this way, the generic type T will be assigned to the type of the value it gets as an argument.ExampleIn this example, we will see how "reified" is helpful to re-use our code and use the same function to perform similar kind of operation regardless of its ... Read More
In Kotlin, "!!" is an operator that is known as the double-bang operator. This operator is also known as "not-null assertion operator". This operator is used to convert any value to a non-NULL type value and it throws an exception if the corresponding value is NULL. In the following example, we will see how to use this double-bang operator.Example 1In this example, we will consider a variable "name" and as a programmer, we want to throw a NULL pointer exception whenever the value of "name" is NULL. Now, execute the following codefun main(args: Array) { var name: ... Read More
List and array are two popular collections supported by Kotlin. By definition, both these collections allocate sequential memory location. In this article, we will take an example to demonstrate the difference between these two types of collections.AttributeArrayListImplementationArray is implemented using Array classList or MutableList interfaces are used to implement a List in KotlinMutableArray is mutable, i.e., the values can be changed.List is immutable in nature. In order to create a mutable list, MutableList interface needs to be used.SizeArray is of fixed size. It cannot increase and decrease in size.MutableList do have 'add' and 'remove' functions in order to increase or ... Read More
Data class is a class that holds the data for an application. It is just like a POJO class that we use in Java in order to hold the data.In Java, for data class, we need to create getter and setter methods in order to access the properties of that class. In Kotlin, when a class is declared as a data class, the compiler automatically creates some supporting methods required to access the member variable of the class. The compiler will create getters and setters for the constructor parameters, hashCode(), equals(), toString(), copy().For a class to be considered as a ... Read More
In every programming language, we need some variable whose value will never change thoroughout the program. In Kotlin too, we have a keyword to create such a variable whose value will remain as constant throughout the program. In order to declare a value as constant, we can use the "const" keyword at the beginning. In this article, we will learn how we can declare a variable as constant in a different way.Example: Top level declarationExampleKotlin const variable can be declared at the top of the programming language and it can be used throughout the file scope.private const val My_TOP_LEVEL_CONST_VAL = ... Read More