Interview Questions

The with() function evaluates an R expression on one or more variables of a data frame and outputs the result without modifying the data frame. The within() function evaluates an R expression on one or more variables of a data frame, modifies the data frame, and outputs the result. Below we can see how these functions work using a sample data […]

Shiny is an open-source R package that allows the easy and fast building of fully interactive web applications and webpages for data science using only R, without any knowledge of HTML, CSS, or JavaScript. Shiny in R offers numerous basic and advanced features, widgets, layouts, web app examples, and their underlying code to build upon […]

Below are several approaches and how to implement them in the caret package of R. To implement these cross-validation methods in R, we need to set the method parameter of the trainControl() function to “cv”, “repeatedcv”, or “LOOCV” respectively, when defining the training control of the model.

Correlation is a measure of the strength and direction of the linear relationships between two variables. It takes values from -1 (a perfect negative correlation) to 1 (a perfect positive correlation). Covariance is a measure of the degree of how two variables change relative to each other and the direction of the linear relationships between […]

Let’s consider three different approaches and how to implement them in the caret package. We need to create a correlation matrix of all the features and then identify the highly correlated ones, usually those with a correlation coefficient greater than 0.75: We need to create a training scheme to control the parameters for train, use […]

A regular expression, or regex, in R or other programming languages, is a character or a sequence of characters that describes a certain text pattern and is used for mining text data. In R, there are two main ways of working with regular expressions:

There are three groups of control statements in R: conditional statements, loop statements, and jump statements. Conditional statements: Loop statements: Jump statements:

While all these functions allow iterating over a data structure without using loops and perform the same operation on each element of it, they are different in terms of the type of input and output and the function they perform.

The switch() function in R is a multiway branch control statement that evaluates an expression against items of a list. It has the following syntax: The expression passed to the switch() function can evaluate to either a number or a character string, and depending on this, the function behavior is different. 1. If the expression evaluates to a number, […]