Programming Articles - Page 2170 of 3363

Suppose we have Roman literals; we have to convert them into an integer. As we know the Roman numerals represent in some different symbols as below −NumeralValueI1V5X10L50C100D500M1000If we see the roman numbers closely, it is like suppose the numeral is 'II', so this is 2, there are two 'I's are added together. For XII, it is 12, so this is actually X + II = 10 + 2 = 12. The roman numerals of 4 are not IIII, it is IV. This is a little tricky.I can be used before V(5) and X(10) to make it 4 and 9 respectivelyX ... Read More

Suppose we have an array of integers. We have to return the indices of two integers, such that if we add them up, we will reach to a specific target that is also given. Here we will take one assumption, that is always there will be one unique solution in the array, so no two set of indices for same target will be there.For an example, suppose the array is like A = [2, 8, 12, 15], and the target sum is 20. Then it will return indices 1 and 2, as A[1] + A[2] = 20.To solve this, we ... Read More

The Fibonacci is a sequence of numbers in which every number after the first two numbers is the sum of the two preceding numbers like 0, 1, 1, 2, 3, 5, 8, 13, 21 and so on. The sequence of Fibonacci numbers defined by using "F(n)=F(n-1)+F(n-2)".In the below example, we can implement the Fibonacci series with the help of Stream API and lambda expression. The Stream.iterate() method returns an infinite sequential ordered stream produced by iterative application of a function to an initial element seed, producing a stream consisting of seed, f(seed), f(f(seed)), etc.Exampleimport java.util.List; import java.util.stream.*; public class FibonacciTest {    public static void ... Read More

IntFunction interface is a functional interface in Java 8 and defined in java.util.function package. This interface accepts an int-valued parameter as input and returns a value of type R. IntFunction interface can be used as an assignment target for a lambda expression or method reference and holds only one abstract method, apply().Syntax@FunctionalInterface public interface IntFunction {    R apply(int value); }Exampleimport java.util.HashMap; import java.util.Map; import java.util.function.IntFunction; public class IntFunctionTest {    public static void main(String[] args) {       IntFunction getMonthName = monthNo -> {  // lambda expression          Map months = new HashMap();          months.put(1, "January");       ... Read More

Java 8 introduced changes in the Comparator interface that allows us to compare two objects. These changes help us to create comparators more easily. The first important method added is the comparing() method. This method receives as a parameter Function that determines the value to be compared and creates Comparator. Another important method is the thenComparing() method. This method can be used to compose Comparator.In the below example, we can sort a list by using the first name with comparing() method and then the last name with the thenComparing() method of Comparator interface.Exampleimport java.util.*; public class MethodReferenceSortTest {    public static void main(String[] ... Read More

ToIntFunction is the built-in functional interface defined in java.util.function package. This functional interface expects an argument as input and produces an int-valued result. It can be used as an assignment target for a lambda expression or method reference. The ToIntFunction interface holds only one method, applyAsInt(). This method performs an operation on the given argument and returns the int-valued result.Syntax@FunctionalInterface public interface ToIntFunction {    int applyAsInt(T value); }In the below example, we can implement ToIntFunction by using lambda expression and method reference.Exampleimport java.util.function.ToIntFunction; import java.time.LocalDate; public class ToIntFunctionInterfaceTest {    public static void main(String[] args) {       ToIntFunction lambdaObj = value -> ... Read More

The ObjIntConsumer interface is a kind of functional interface and defined in java.util.function package. This functional interface expects an object-valued and int-valued argument as input and does not produce any output. It holds only one functional method, accept(Object, int).Syntax@FunctionalInterface    public interface ObjIntConsumer {       void accept(T t, int value) }In the below examples, we can implement the ObjIntConsumer interface by using a lambda expression.Example-1import java.util.function.*; public class ObjIntConsumerInterfaceTest1 {    public static void main(String args[]) {       ObjIntConsumer objIntConsumberObj = (t, value) -> {   // lambda expression          if(t.length() > value) {         ... Read More

As a versatile language and also availability of very large number of user supported modules, we find that python is also good at OS level programming. In this article we will see how python can access the registry of a windows operating system.We need to import the module named winreg into the python environment.In the below example we use the winreg module to first connect to the registry using the ConnectRegistry function and then access the registry using OpenKey function. Finally we design a for loop to print the result of the keys accessed.Exampleimport winreg #connecting to key in registry ... Read More

As part of data analysis, we will come across scenarios to remove the negative values form a dictionary. For this we have to loop through each of the elements in the dictionary and use a condition to check the value. Below two approaches can be implemented to achieve this.Using for loopW simply loop through the elements of the list using a for loop. In every iteration we use the items function to compare the value of the element with the 0 for checking negative value.Example Live Demodict_1 = {'x':10, 'y':20, 'z':-30, 'p':-0.5, 'q':50} print ("Given Dictionary :", str(dict_1)) final_res_1 ... Read More

As part of data analysis require to filter out values from a list meeting certain criteria. In this article we'll see how to filter out only the even values from a list.We have to go through each element of the list and divide it with 2 to check for the remainder. If the remainder is zero then we consider it as an even number. After fetching these even numbers from a list we will put a condition to create a new list which excludes this even numbers. That new list is the result of the filtering condition we applied.Using for ... Read More