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The column names in an R data frame are an important part of the data because by reading the column names any viewer is likely to understand the theoretical background behind it. If that name is not appropriate then we might want to change it. While using the aggregate function to calculate mean or any other statistical summary, it is possible to change that name with another name by defining the new name with list.ExampleConsider the below data frame −set.seed(1) x1
Let’s say, we have an array of arrays that contains some elements like this −const arr = [3, 5, 7, 2, [4, NaN, null, 4, 8, [3, undefined, 24, null], null, 5, 1], NaN, 45, 2, 1];Our job is to write a recursive function that takes in this nested array and replaces all the fale values inside the array (NaN, undefined and null) with 0.Therefore, let's write the code for this function −Exampleconst arr = [3, 5, 7, 2, [4, NaN, null, 4, 8, [3, undefined, 24, null], null, 5, 1], NaN, 45, 2, 1]; const recursiveSimplify = (arr) => ... Read More
We are required to write a function, say reverseSum() that takes in two arrays of Numbers, let’s say first and second and returns a new array that contains, Sum of first element of first array and last element of second array as first element, sum of second element of first array and second last element of second array, and so on.When any of the array runs out of element before the other, we simply push all the remaining elements to the array. Therefore, let's write the code for this function −Exampleconst first = [23, 5, 7, 2, 34, 7, 8]; ... Read More
We are required to write a function that takes a positive integer n and returns an array of next n leap years. We will break this problem into three parts −Part 1: Finding current year via JSThe code to find current year via JS will be −// getting the current year from a new instance of Date object const year = new Date().getFullYear();Part 2: Checking for leap yearWe will now write a function isLeap() that takes in a number and returns a boolean based on the number being a leap year or not.A year is considered as a leap year ... Read More
We are required to write a function with a while-statement that determines the length of the largest consecutive subarray in an array of positive integers.For instance −If the input array is −const input = [6, 7, 8, 6, 12, 1, 2, 3, 4] --> [1, 2, 3, 4]Then the output should be −4If the input array is −const input = [5, 6, 1, 8, 9, 7] --> [8, 9]Then the output should be −2Therefore, let’s write the code for this function −Exampleconst arr = [6, 7, 8, 6, 12, 1, 2, 3, 4]; const arr1 = [5, 6, 1, 8, ... Read More
Given an array of arrays, each of which contains a set of numbers. We have to write a function that returns an array where each item is the sum of all the items in the corresponding subarray.For example −If the input array is −const numbers = [ [1, 2, 3, 4], [5, 6, 7], [8, 9, 10, 11, 12] ];Then output of our function should be −const output = [10, 18, 50];So, let’s write the code for this function −Exampleconst numbers = [ [1, 2, 3, 4], [5, 6, 7], [8, 9, 10, 11, ... Read More
Let’s say, we are required to write a recursive function that sums all the elements of an array of Numbers but with a twist and the twist is that the recursive function we write cannot initialize any extra variable (memory).Like we cannot use a variable to store the sum or to keep a count of the index of the array, it all has to be using what we already have.Here’s the solution −We already have an array and can use its first element (i.e., the element at zeroth index to hold the recursive sum).The approach is that we repeatedly pop ... Read More
We are required to write a JavaScript function that takes in a number and returns a boolean based on the fact whether or not it comes in the fibonacci series.For example −If the function call is like this −fibonacci(12); fibonacci(89); fibonacci(55); fibonacci(534);Then the output should be −False true true falseNow, let’s write a recursive solution to this problem −Exampleconst fibonacci = (query, count = 1, last = 0) => { if(count < query){ return fibonacci(query, count+last, count); }; if(count === query){ return true; } return false; }; console.log(fibonacci(12)); console.log(fibonacci(55)); ... Read More
Let’s say, we have two arrays, one contains the correct answer strings of some questions and one contains the answers attempted by a candidate, but somehow the arrays got shuffled and now they don’t have answers in corresponding order. But we can be sure that no two questions had the same answers.Our job now is to write a function that takes these two arrays, checks them for common elements and finds all the common elements between them and then calculates the marks percentage of the candidate based on the count of common answers.Let’s write the code for this function −Exampleconst ... Read More
Let’s say, we have an array of objects like this −Exampleconst arr = [ {text:'use'}, {text: 'secur'}, {text: 'form'}, {text: 'user'}, {text: 'users'}, {text: 'form'}, {text: 'secur'}, {text: 'sec'}, {text: 'users'}, {text: 'secu'}, {text: 'secur'}, {text: 'for'}, {text: 'form'} ]Our job is to write a function that takes in this array and a number n and the function should return an array of n objects which have the longest string value for the text key and all the objects should have a unique value for the text ... Read More