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To create a random sample by excluding missing values of a data frame column, we can use sample function and the negation of is.na with the column of the data frame.For Example, if we have a data frame called df that contains a column X which has some NAs then we can create a random sample of size 100 of X values by using the following command −sample(df$X[!is.na(df$X)],100,replace=TRUE).Example 1Following is the code snippet to create dataframe −x
A Collection is an object where developers can group different types of related objects in one place. There are different kinds of collections present in Kotlin library such as List, Array, etc.In this article, we will see how we can sort a collection by different properties present inside that collection. In order to do that, we will be taking the help of the following two functions provided by the Kotlin library.sortedWith()compareBy()sortedWith()sortedWith() is a function provided by the Kotlin library that returns a list of all the elements sorted by a specified comparator. According to official Kotlin documentation, the function definition ... Read More
An array is a type of data structure that contains a definite number of similar types of values or data. In this data structure, every element can be accessed using the array index that usually starts at "0".In Kotlin, arrays can be created using the function arrayOf() or using an Array constructor.Important points regarding Arrays in Kotlin −Arrays are stored in a sequence as per the memory location is concerned.All the elements in an array can be accessed using their index.Arrays are mutable in nature.In conventional programming, the size usually declared along with its initialization, hence we can conclude that ... Read More
In Kotlin, we can declare a variable using two different keywords: one is var and the other one is val. In this article, we will take an example and demonstrate how these declarations are different from each other.AttributevarvalDeclarationvar varName="hello World"val sName = "tutorialspoint.com"ImmutabilityMutableImmutableNo. of times a variable can be assigned Can be assigned multiple times.Cannot be assigned multiple times.Reassigned Can be reassignedCannot be reassignedExampleIn the following example, we will see how we can declare two different variables using "val" and "var". We will also see that the variable declared using 'var' can be changed, while the variable declared using 'val' cannot be ... Read More
const KeywordThe const keyword is used in Kotlin whenever the variable value remains const throughout the lifecycle of an application. It means that const is applied only on immutable properties of the class. In simple words, use const to declare a read-only property of a class.There are some constraints that are applied to the const variable. They are as follows −const can only be applied to the immutable property of a class.It cannot be assigned to any function or any class constructor. It should be assigned with a primitive data type or String.The const variable will be initialized at compile-time.ExampleIn ... Read More
Kotlin library provides two different access modifiers for property declaration.In this article, we will highlight the difference between these two access modifiers and how we can use them in our application.LateinitIn order to create a "lateInit" variable, we just need to add the keyword "lateInit" as an access modifier of that variable. Following are a set of conditions that need to be followed in order to use "lateInit" in Kotlin.Use "lateInit" with a mutable variable. That means, we need to use "var" keyword with "lateInit"."lateInit" is allowed only with non-NULLable data types."lateInit" does not work with primitive data types."lateInit" can ... Read More
Any variable which is initialized after its declaration is known as a "late initialized variable". In conventional programming languages, any non-NULL type of variable need to be initialized in the constructor. But sometimes, by mistake, developers forget to do these NULL checks which causes a programming error. In order to avoid this situation, Kotlin introduced a new modifier called as "lateInit". Along with this modifier, Kotlin provides a couple of methods to check whether this variable is initialized or not.In order to create a "lateInit" variable, we just need to add the keyword "lateInit" as an access modifier of that ... Read More
In Java, "static" keyword is used for efficient memory management. Once a variable or method is declared as static, then the JVM will allocate memory for these variable only once. Usually static variables are used to declare common properties of a class, for example, "Name of the institution". In the following example, we will see how to use the static keyword.Example of Static in using JavaIn order to demonstrate how static works in Java, we will access our online Java compiler and we will create a Test class. Inside Test, we will try to create a static variable along with ... Read More
Exception is an important aspect of any programming language. It prevents our code from generating incorrect output at runtime.The concept of exception in Kotlin is very much same as it is in Java. All the exceptions in Kotlin are the descendants of Throwable class. In Kotlin, developers do have the privilege to create their own custom Exception.Custom Exceptions are a part of unchecked exceptions which means they will be thrown at the runtime.Before getting into custom exceptions in Kotlin, let's take a look checked and unchecked exceptions.Checked ExceptionsChecked exceptions are those which are checked at the compile time. In the ... Read More
The timers module contains functions that can execute code after a certain period of time. You do not need to import the timer module explicitly, as it is already globally available across the emulated browser JavaScript API.Timers module is mainly categorised into two categoriesScheduling Timers − This timer schedules the task to take place after a certain instant of time.setImmediate()setInterval()setTimeout()Cancelling Timers − This type of timers cancels the scheduled tasks which is set to take place. ClearImmediate()clearInterval()clearTimeout()Scheduling Timers1. setTimeout() MethodThe setTimeout() method schedules the code execution after a designated number of milliseconds. Only after the timeout has occurred, the code ... Read More