R programming language which can be used for several purposes including statistical analysis, data visualization, predictive modeling etc. Here we have compiled some R interview questions and answers that you should prepare for the interview. Going through these questions will help you to understand some of the important questions that can be asked in the interview.

#### What is R?

The development of statistical software and evaluation of data is the purpose of R. R comprises machine learning algorithms, time series, linear regression, statistical inference etc. Several of the R libraries are written in R. However for heavy computational task, one can take up C, C++ and Fortran codes.

#### How R Commands are Written?

R commands are written by using # at the beginning of the line of code.

Name Some Functions Available in “dplyr” Package.

#### Functions in dplyr package:

filter

Select

arrange

mutate

count

#### What are the Advantages of R?

R is used for controlling and manipulating data.

R is an open source software

There are no restrictive license

There are excellent graphical capabilities.

R initiates on several Operating System and various hardware. It also initiates on 32 & 64 bit processors.

How Many Sorting Algorithms are Available?

Bubble Sort

Selection Sort

Quick Sort

Merge Sort

Bucket Sort

#### How to Create New Variable in R Programming?

Assignment operator ‘<-’ is used for creating new variable in R.

For e.g. mydata$sum <- mydata$x1 + mydata$x2

#### What are R Packages?

Collection of data are called packages. These packages are saved in library.

#### What is the Workspace in R?

Workspace is the present R working environment which comprises any user defined objects comprising vector, lists etc.

#### What is the Power Analysis?

Power analysis is applied for experimental design. It is helpful for making out the effect of given sample size.

#### Which Method is Used for Exporting the Data in R?

There are several ways to export the data into another format including SPSS, SAS, Excel Spreadsheet etc.

#### What is the Use of Coin Package in R?

The Coin package offers an implementation of a general framework for conditional inference procedures generally called as permutation tests.

#### What is GGobi?

GGobi is an open source program which is used for visualization for getting insight into high dimensional typed data.

#### What is iPlots?

iPlots is a package that offers bar plots, box plots, mosaic plots, scatter plots, parallel plots, and histograms.

#### Which Method is Used for Exporting the Data in R?

There are many ways to export the data into another formats like SPSS, SAS , Stata , Excel Spreadsheet.

#### Can you Write and Explain Some of the Most Common Syntax in R?

**Few of the basic syntax for R that is used frequently are:**

# —used to bring in a line of comments

“”-they indicate a string data type in R

<- —assignment operator (know this correctly as this is one of the strange things of R. It is not = for assignment operator.

\ — the backsplash denotes the escape character in R.

How do you Assign a Variable in R?

myVar <- 20

print(myVar

**The following is also valid:**

myVar = 15

print(myVar)

Assigning variables can also be performed the other way round.

“helloWorld” -> myVar

The string “helloWorld” is now saved in the myVar variable. Note that this would generate an error if we got confused and attempted to plug an undefined variable object into a string, as in:

myVar -> “helloWorld”

Error: object ‘myVar’ not found

#### What are the Different Data Types/Objects in R?

At the time of assigning a variable, R does not ask users to declare a data type. On the other hand, everything in R correlated to an R data object. At the time of assigning a variable in R, you assign it a data object. That object’s data type makes up the data type of the variable. The frequently applied data objects are:

Vectors

Matrices

Arrays

Lists

Data frames

Factors

#### How do you Install a Package in R?

Several ways are available to install a package in R. The GUI Is also applied for some.

Key in the following into your console and hit enter:

install.packages(“package_name”)

library(package_name)

While the first command installs the package the second command loads the package into the session.

#### What is a Factor Variable, and What is its Purpose?

A factor variable is a type of categorical variable. It accepts eight character or numeric string values. One of the major reasons to apply a factor variable is that it can be applied in statistical modeling with great correctness. Memory efficiency is another reason for applying them. You have to just use the factor() function for creating a factor variable.

#### What are Different Ways to Call a Function in R?

A function in R can be called in 3 ways.

First method- call by means of the position of the arguments.

Second method-call by means of the name of the arguments

Third method-call by means of default arguments.

Give the Syntax for Creating Scatterplot Matrices.

Pairs (Formula, Data)

Here formula represents the series of variables that are applied in pairs. Data represents the data set from which the variables will be considered.

#### In R, How Missing Values are Represented ?

NA (Not Available) is the sign used for representing missing values in R.

#### Explain How Data is Aggregated in R?

This is done by collapsing data in R by applying one or more BY variables. While using the aggregate() function the BY variable should be available in the list.

Hope these questions help you to understand what questions may be asked in an R interview. We have prepared them with care and we believe you go through them diligently for cracking the interviews with ease.

**What is the difference between %% and %|%.**

The %% offers a reminder of the diversion of the first vector with the second, and the %|% provides the quotient of the diversion of the first vector with the second.

**How to use apply() function in R?**

The function apply() used to implement the same function to each of the elements in an array. Ex, discovering the mean of the rows in every row.

#### Define aggregate() function

The aggregate() function is applied to aggregate data in R. Two methods are applied to collapse data by using one or more BY variables and the other is an aggregate() function in that BY variable would be in the list.

#### What is the difference between lapply and sapply?

The lapply is applied to display the output in list form while sapply is used to display the output in the form of a data frame or vector.

#### Define DoBy package

DoBy package is used to describe the table using model formula and function.

#### What is the use of the table() function?

The table() function is to generate the frequency in R.

#### Define lattice package

The lattice package is used to improve the base R graphics by providing better defaults and can show multivariate relationships easily.

#### Describe anova() function

The ANOVA() function is used to compare the nested models.

#### What is the leaps() function?

The leaps() function is applied to perform defined under leaps package and all-subsets regression.

#### What is the full form of MANOVA and the use of it

MANOVA is the acronym Multivariate Analysis of Variance and is used to verify more than one dependant variable at the same time.

#### What is the goal of integration of R and Hadoop?

The integration of R and Hadoop is used for executing R code and to access the data stored in Hadoop.

#### Differentiate sample() and subset in R.

The sample() is the method used to select a random sample of size and form a dataset while subset is the method used to select variables and observations.

#### Describe fitdistr() function

The fitdistr() function is used to provide the maximum fitting of the Univariate distribution and comes under the MASS package.

#### What are iPlots and GGobi denote?

The iPlots is a package that provides bar plots, box plots, mosaic plots, histograms, parallel plots, and scatter plots and the GGobi is an open-source program used in visualization to explore high dimensional typed data in R programming.

#### Explain t-test() in R?

The t-test() is the function used to determine the mean of two groups and verify that they are equal or not.

#### What are the integration methods of R to Hadoop?

R Hadoop, Hadoop Streaming, RHIPE, and ORCH are the methods used to integrate R with Hadoop.

#### Describe the random walk model in R?

A random walk model is the simplest way of a non-stationary process and it has no specified mean or variance. It has strong dependence over time and the changes and increments of random walk are white noise and simulating random walk in R.

#### Define white noise model

The white noise model is a basic time series and a simple stationary process. It has a fixed constant variance, fixed constant mean, and no correlation over time. It can be simulated using the following way.

arima.sim(model=list(order=c(0,0,0)), n=50)->wn

#### List out the names of the packages used for data manipulation

MICE, missFores, Mi, Hmisc, Amelia, and imputeR are the popular packages of R used for data manipulation.

**What is initialize() function in R**

Initialize() is the function that is used to initialize the private data members while declaring the object.

These R Interview Questions and Answers are updated in 2021 as per the frequently asked questions in the interviews of top companies around the globe. We provide the best R Programming Training in Chennai at Softlogic for helping the students to obtain the industry-specific knowledge and skills to perform from day one. Stay updated with our R Course and Interview questions and answers as we update them regularly.