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R Programming Interview Questions and Answers

Updated May 29, 2019

What is R Programming?

R is a programming language that is used for statistical analysis, reporting, graphical representation, machine learning, and data analysis. At its core, it is an interpreted computer programming language whose libraries are mostly written in R itself. For more complex tasks, the libraries written in C, C++, and Fortran are used.

What are the advantages of using R language?

The advantages of using R are as follows:

  • It used for complicated programming projects like statistical analysis, reporting, graphical uts.
  • Representation, machine learning, and data analysis.
  • Being an interpreted language it can be executed on any compiler.
  • It is a very powerful language as it is a vector language and many additional functions can be added to it easily by developers.
  • As it is open source the language undergoes frequent development, package additions, bug fixes and enhancements in its code.

What is a factor in R programming?

In R, factors are used for storing data objects as levels and to categorize the data. Here both integers and strings can be stored. They are extensively used for data analysis and statistical modelling as they can handle unique values properly. Factors are represented through the factor functions that take in vectors as inp

Why R programming is important in big data?

R is very useful in data analysis as there are multiple useful libraries and packages for data wrangling. This helps data scientists to tackle large datasets and simplify the data to perform further analysis. It has ggplot2 and ggedit packages for data visualization.

How to calculate the execution time of a program in R?  

The program execution can be measured through different methods that are:

  • time().
  • time(), for measuring processes.
  • Using the R library tictoc.
  • time()

How to take input in R programming?

In an interactive session in R, the readline() function can be sued to accept values from the user as input and use for other operations. A single element character vector will be returned by this function. Inside the readline() function the prompt argument can be used to give the user a hint about the text that is expected as input.

What is a vector in R programming?

A vector is a data structure used in R that is used for holding the values of the same data type. Integer, character, complex, double and raw are the common data types supported by vectors. The length of a vector can be checked using the length() function. The type of vector can be checked using the typeof() function.

What is an array in R programming?

An array in R is a data structure that can store data in many dimensions. In this structure, the data is stored as rows, columns, and matrices.  Arrays store only a single data type and are created using the array() function.

What is a matrix in R programming?

Matrices are data structures in R that have elements arranged in a two-dimensional rectangular layout. It is similar to a vector but has the dimension attribute that checks all attributes of the object. They are used for mathematical calculations for numeric elements. A matrix can be created through the matrix() function.

How commands are written in R?

Commands are written in the R language using the Rscript interpreter. The commands can be executed in the command line using the $ R command.

How many data structures are there in R?

The different types of data structures in R are as follows:

  • Vector
  • List
  • Factor
  • Matrix
  • Data frame
  • String

What are the ways to call a function in R?

A function in R has different parts like a function name, arguments, return value and the main function body. The basic method to call a function is to mention the function name in the function call statement and pass the required arguments along with it.

How do you use program R to make a Histogram?

A histogram can be created using a hist() function that takes in an argument like vectors. The dataset can be passed on to the function hist() as an argument for creating the histogram. If a specific portion of the dataset needs to be displayed, the $ symbol needs to be used along with the argument mentioning the row or column. The histogram can be improved by providing more arguments that have values.

What is the next statement in R?

The next statement in R is used when the current iteration in the R program needs to be skipped without stopping the program execution. When the next statement is encountered, the parser skips the current evaluation and goes to the next iteration. This statement is used along with for loops, while loops, if and else if statements.

What are various packages in R?

Packages in R are libraries that contain multiple functions, sample data, and code. Some packages are installed during installation by default. Other packages can be installed and loaded based on the requirements of the users.

Where are R packages stored?

The R packages are stored in the library directory.

What is the difference between R and Python?

The differences between R and Python are as follows:

R Programming


Used mainly for data analysis and statistical modelling.

Used for application development, deployment, back end development, etc.

It is difficult to learn at the beginning.

It is easier than R to learn the basic at the beginner.

The primary users are data scientists and researchers.       

It is primarily used by application developers, machine learning engineers, security analysts, and back end developers. 

The Comprehensive R Archive Network is used as the repository for packages.

The PyPi is the Python Package Index used as a package repository.

In the case of data analysis, it is the best choice for analysts.

It is popular for data analysis but not as widely used as R.

How to delete a column in R?

The most common way of removing a column in R is to set it to NULL. This way the internal pointer of the data frame will be set to NULL and space will be released and the column will be removed. The following code can be used:

dataframe$column_name <- NULL

Other ways to delete columns are:

  • By using the subset() function and deleting the column by name.
  • Deleting by index numbers

How to write a function in R?

Functions can be written in R using the simple structure consisting of the function name, arguments and the function body.

The following code can be used:

Function_name <- function(argument1, argument2, ... ){

Function statements

Return statement (object)