Presenting 40+ most important **Data science R Programming interview questions and answers**. These are the top 40 **Data science interview questions** focusing on R Language for Statistic and Data science jobs. The **data scientist interview questions and answers** given below are some of the most frequently asked questions for both data scientist theory based interview rounds and r programming coding interview questions.

# R interview questions for freshers

**Q.1 Which Package In R Supports The Exploratory Analysis Of Genomic Data?**

**Answer:**

Adegenet.

**Q.2 Explain The Various Benefits Of R Language?**

**Answer:**

The R programming language includes a set of rich software suite that is used for graphical representation, statistical computing, data manipulation and calculation.

**Q.3 What are the highlights of R programming environment?**

**Answer:**

An extensive collection of tools for data analysis Operators for performing calculations on matrix and array Data analysis technique for graphical representation A highly developed yet simple and effective programming language. It extensively supports machine learning applications. It acts as a connecting link between various software, tools and datasets. Create high quality reproducible analysis that is flexible and powerful. Provides a robust package ecosystem for diverse needs. It is useful when you have to solve a data-oriented problem

**Q.4 How Missing Values And Impossible Values Are Represented In R Language?**

**Answer:**

NaN (Not a Number) is used to represent impossible values whereas NA (Not Available) is used to represent missing values. The best way to answer this would be to mention that deleting missing values is not a good idea because the probable cause for missing value could be some problem with data collection or programming or the query. It is good to find the root cause of the missing values and then take necessary steps handle them.

**Q.5 What Is The Process To Create A Table In R Language Without Using External Files?**

**Answer:**

MyTable= data.frame ()

edit (MyTable)

The above code will open an Excel Spreadsheet for entering data into MyTable.

**Q.6 How Can You Debug And Test R Programming Code?**

**Answer:**

R code can be tested using Hadley’s testthat package.

**Q.7 What Are The Rules To Define A Variable Name In R Programming Language?**

**Answer:**

A variable name in R programming language can contain numeric and alphabets along with special characters like dot (.) and underline (-). Variable names in R language can begin with an alphabet or the dot symbol. However, if the variable name begins with a dot symbol it should not be a followed by a numeric digit.

**Q.8 What Do You Understand By A Workspace In R Programming Language?**

**Answer:**

The current R working environment of a user that has user defined objects like lists, vectors, etc. is referred to as Workspace in R language.

**Q.9 Which Function Helps You Perform Sorting In R Language?**

**Answer:**

Order ()

### Q.10 How Will You List All The Data Sets Available In All R Packages?

**Answer:**

Using the below line of codedata(package = .packages(all.available = TRUE))

**Data Science interview questions and answers**

**Q.11 Which Function Is Used To Create A Histogram Visualisation In R Programming Language?**

**Answer:**

Hist()

**Q.12 Write The Syntax To Set The Path For Current Working Directory In R Environment?**

**Answer:**

Setwd(“dir_path”)

**Q.13 What Will Be The Output Of Runif (7)?**

**Answer:**

It will generate 7 random numbers between 0 and 1.

**Q.14 What Is R Base Package?**

**Answer:**

R Base package is the package that is loaded by default whenever R programming environent is loaded .R base package provides basic fucntionalites in R environment like arithmetic calcualtions, input/output.

**Q.15 How Will You Combine Multiple Different String Like “data”, “science”, “in” ,“r”, “programming” As A Single String “data_science_in_r_programmming” ?**

**Answer:**

paste(“Data”, “Science”, “in” ,“R”, “Programming”,sep=”_”)

**Q.16 Write A Function To Extract The First Name From The String “mr. Tom White”?**

**Answer:**

substr (“Mr. Tom White”,start=5, stop=7)

**Q.17 How Will You Merge Two Dataframes In R Programming Language?**

**Answer:**

Merge () function is used to combine two dataframes and it identifies common rows or columns between the 2 dataframes. Merge () function basically finds the intersection between two different sets of data.

**Q.18 R Programming Language Has Several Packages For Data Science Which Are Meant To Solve A Specific Problem, How Do You Decide Which One To Use?**

**Answer:**

CRAN package repository in R has more than 6000 packages, so a data scientist needs to follow a well-defined process and criteria to select the right one for a specific task. When looking for a package in the CRAN repository a data scientist should list out all the requirements and issues so that an ideal R package can address all those needs and issues. The best way to answer this Q. is to look for an R package that follows good software development principles and practices. For example, you might want to look at the quality documentation and unit tests. The next step is to check out how a particular R package is used and read the reviews posted by other users of the R package. It is important to know if other data scientists or data analysts have been able to solve a similar problem as that of yours. When you in doubt choosing a particular R package, I would always ask for feedback from R community members or other colleagues to ensure that I am making the right choice.

**Q.19 Dplyr Package Is Used To Speed Up Data Frame Management Code. Which Package Can Be Integrated With Dplyr For Large Fast Tables?**

**Answer:**

data.table

**Q.20 Explain About Data Import In R Language?**

**Answer:**

R Commander is used to import data in R language. To start the R commander GUI, the user must type in the command Rcmdr into the console. There are 3 different ways in which data can be imported in R language. Users can select the data set in the dialog box or enter the name of the data set (if they know). Data can also be entered directly using the editor of R Commander via Data->New Data Set. However, this works well when the data set is not too large. Data can also be imported from a URL or from a plain text file (ASCII), from any other statistical package or from the clipboard.

**Data Science Interview questions in r programming**

**Q.21 Which Function In R Language Is Used To Find Out Whether The Means Of 2 Groups Are Equal To Each Other Or Not?**

**Answer:**

t.tests ()

**Q.22 What Is The Best Way To Communicate The Results Of Data Analysis Using R Language?**

**Answer:**

The best possible way to do this is combine the data, code and analysis results in a single document using knitr for reproducible research. This helps others to verify the findings, add to them and engage in discussions. Reproducible research makes it easy to redo the experiments by inserting new data and applying it to a different problem.

**Q.23 How Many Data Structures Does R Language Have?**

**Answer:**

R language has Homogeneous and Heterogeneous data structures. Homogeneous data structures have same type of objects – Vector, Matrix ad Array. Heterogeneous data structures have different type of objects – Data frames and lists.

**Q.24 How Many Data Structures Does R Language Have?**

**Answer:**

R language has Homogeneous and Heterogeneous data structures.

**Q.25 What Are The Different Type Of Sorting Algorithms Available In R Language?**

**Answer:**

Bucket Sort, Selection Sort, Quick Sort, Bubble Sort, Merge Sort

**Q.26 How Can You Add Datasets In R?**

**Answer:**

rbind () function can be used add datasets in R language provided the columns in the datasets should be same.

**Q.27 What Is The Difference Between Data Frame And A Matrix**

In R?

In R?

**Answer:**

Data frame can contain heterogeneous inputs while a matrix cannot. In matrix only similar data types can be stored whereas in a data frame there can be different data types like characters, integers or other data frames.

**Q.28 What Is The Memory Limit In R?**

**Answer:**

8TB is the memory limit for 64-bit system memory and 3GB is the limit for 32-bit system memory.

**Q.29 What Are The Data Types In R On Which Binary Operators Can Be Applied?**

**Answer:**

Scalars, Matrices ad Vectors.

**Q.30 How Do You Create Log Linear Models In R Language?**

**Answer:**

Using the loglm () function

**R Programming language interview questions**

**Q.31 What Will Be The Class Of The Resulting Vector If You Concatenate A Number And A Character?**

**Answer:**

character

**Q.32 What Are Factor Variable In R Language?**

**Answer:**

Factor variables are categorical variables that hold either string or numeric values. Factor variables are used in various types of graphics and particularly for statistical modelling where the correct number of degrees of freedom is assigned to them

**Q.33 How Do You Create Log Linear Models In R Language?**

**Answer:**

Using the loglm () function

**Q.34 Write A Function In R Language To Replace The Missing Value In A Vector With The Mean Of That Vector?**

**Answer:**

mean impute <- function(x) {x [is.na(x)] <- mean(x, na.rm = TRUE); x}

**Q.35 How Will You Read A .csv File In R Language?**

**Answer:**

read.csv () function is used to read a .csv file in R language.

**Q.36 How Do You Write R Commands?**

**Answer:**

The line of code in R language should begin with a hash symbol (#).

**Q.37 How Will You Measure The Probability Of A Binary Response Variable In R Language?**

**Answer:**

Logistic regression can be used for this and the function glm () in R language provides this functionality.

**Q.38 What Is The Use Of Sample And Subset Functions In R Programming Language?**

**Answer:**

Sample () function can be used to select a random sample of size ‘n’ from a huge dataset. Subset () function is used to select variables and observations from a given dataset.

**Q.39 How Will You Create Scatter Plot Matrices In R Language?**

**Answer:**

A matrix of scatter plots can be produced using pairs. Pairs function takes various parameters like formula, data, subset, labels, etc.

**Q.40 What Is The Difference Between Library() And Require() Functions In R Language?**

**Answer:**

There is no real difference between the two if the packages are not being loaded inside the function. require () function is usually used inside function and throws a warning whenever a particular package is not found. On the flip side, library () function gives an error message if the desired package cannot be loaded.

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*coding questions based on R and Python***Q.41 Explain The Usage Of Which() Function In R Language?**

**Answer:**

which() function determines the position of elements in a logical vector that are TRUE.

**Q.41 Python or R – Which one would you prefer for text analytics?**

**Answer:**

Python would be the best option because it has Pandas library that provides easy to use data structures and high-performance data analysis tools. R is more suitable for machine learning than just text analysis. Python performs faster for all types of text analytics.

**Q.42 Where to use R & Python?**

**Answer:**

R can be used whenever the data is structed. Python is efficient to handle unstructured data. R can’t handle high volume data. Python backend working with Theano/tensor made it easy to perform it as fast comparing with R.

**Q.43 How Is A Data Object Represented Internally In R Language?**

**Answer:**

unclass (as.Date (“2016-10-05″))

**Q.44 What Is The Best Way To Use Hadoop And R Together For Analysis?**

**Answer:**

HDFS can be used for storing the data for long-term. MapReduce jobs submitted from either Oozie, Pig or Hive can be used to encode, improve and sample the data sets from HDFS into R. This helps to leverage complex analysis tasks on the subset of data prepared in R.

**Q.45 What Is The Command Used To Store R Objects In A File?**

**Answer:**

save (x, file=”x.Rdata”)

**Q.46 In Base Graphics System, Which Function Is Used To Add Elements To A Plot?**

**Answer:**

boxplot () or text ()

**Q.47 Explain About The Significance Of Transpose In R Language?**

**Answer:**

Transpose t () is the easiest method for reshaping the data before analysis.

**Q.48 What Are With () And By () Functions Used For?**

**Answer:**

with() function is used to apply an expression for a given dataset and by() function is used for applying a function each level of factors.