R Interview Questions And Answers

R Interview Questions list for experienced

  1. Explain what is R?
  2. List out some of the function that R provides?
  3. Explain how you can start the R commander GUI?
  4. In R how you can import Data?
  5. Mention what does not 'R' language do?
  6. Explain how R commands are written?
  7. How can you save your data in R?
  8. Mention how you can produce co-relations and covariances?
  9. Explain what is t-tests in R?
  10. Explain what is With () and By () function in R is used for?
  11. What are the data structures in R that is used to perform statistical analyses and create graphs?
  12. Explain general format of Matrices in R?
  13. In R how missing values are represented ?
  14. Explain what is transpose?
  15. Explain how data is aggregated in R?
  16. What is the function used for adding datasets in R?
  17. What is the use of subset() function and sample() function in R ?
  18. Explain how you can create a table in R without external file?
  19. How to make a great R reproducible example?
  20. How to join data frames in R (inner, outer, left, right)?
  21. How to sort a dataframe by column(s) in R?
  22. In R, why is `[` better than `subset`?
  23. what are the Tricks to manage the available memory in an R session?
  24. what are the General suggestions for debugging R?
  25. How to name variables on the fly in R?
  26. How to use R\'s ellipsis feature when writing your own function?
  27. How to group columns by sum in R?
  28. How to do vlookup and fill down (like in excel) in R?
  29. how to Convert year and month to a date in R?
  30. In R, what is the difference between the [] and [[]] notations for accessing the elements of a list?
  31. How to plot two histograms together in R?
  32. How to Calculate moving average in R?
  33. How to trim leading and trailing whitespace in R?
  34. Force R not to use exponential notation (e.g. e+10)?
  35. Painless way to install a new version of R (on Windows)?
  36. How can we read command line parameters from an R script?
  37. How to change language settings in R?
  38. What is your favorite R debugging trick?
  39. How to set limits for axes in ggplot2 R plots?
  40. Why are loops slow in R?
  41. What ways are there to edit a function in R?
  42. How can we make xkcd style graphs in R?
  43. How to Correctly Use Lists in R?
  44. How do we replace NA values with zeros in R?
  45. How to write trycatch in R?
  46. How to print R graphics to multiple pages of a PDF and multiple PDFs?
  47. What are Replacement Functions in R?
  48. In R, what exactly is the problem with having variables with the same name as base R functions?
  49. How to parse milliseconds in R?
  50. How to see the source code of R .Internal or .Primitive function?
  51. s there a R function that applies a function to each pair of columns?
  52. List some of the advantages of R.
  53. What languages R is written in?
  54. What does the R means in the R language?
  55. WHICH IS FAST R or PYTHON?
  56. What is the role of R in It world?

R interview questions and answers on advance and basic R with example so this page for both freshers and experienced condidate. Fill the form below we will send the all interview questions on R also add your Questions if any you have to ask and for apply in R Tutorials and Training course just send a mail on info@pcds.co.in in detail about your self.

Top R interview questions and answers for freshers and experienced

What is R ?

Answer : R is a free, open-source programming language and software environment for statistical computing, bioinformatics, and graphics. Please supplement your question with a minimal reproducible example. For statistical questions please use http://stats.stackexchange.com

Questions : 1 :: Explain what is R?

R is data analysis software which is used by analysts, quants, statisticians, data scientists and others.As  R is a programming language for statistical computing and graphics. The R language is...View answers

Questions : 2 :: List out some of the function that R provides?

The function that R provides are • Mean • Median • Distribution • Covariance • Regression • Non-linear • Mixed Effects • GLM • GAM....View answers

Questions : 3 :: Explain how you can start the R commander GUI?


Typing the command, (“Rcmdr”) into the R console starts the R commander GUI.

Questions : 4 :: In R how you can import Data?

You use R commander to import Data in R, and there are three ways through which you can enter data into it • You can enter data directly via Data  New Data Set • Import data from a...View answers

Questions : 5 :: Mention what does not 'R' language do?

• Though R programming can easily connects to DBMS is not a database • R does not consist of any graphical user interface • Though it connects to Excel/MS office easily, R language...View answers

Questions : 6 :: Explain how R commands are written?


In R, anywhere in the program you have to preface the line of code with a #sign, for example • # subtraction • # division • # note order of operations exists

Questions : 7 :: How can you save your data in R?

To save data in R, there are many ways, but the easiest way of doing this is Go to Data > Active Data Set > Export Active Data Set and a dialogue box will appear, when you click ok the...View answers

Questions : 8 :: Mention how you can produce co-relations and covariances?

You can produce co-relations by the cor () function to produce co-relations and cov () function to produce covariances.

Questions : 9 :: Explain what is t-tests in R?


In R, the t.test () function produces a variety of t-tests. T-test is the most common test in statistics and used to determine whether the means of two groups are equal to each other.

Questions : 10 :: Explain what is With () and By () function in R is used for?

•With() function is similar to DATA in SAS, it apply an expression to a dataset. • BY() function applies a function to each level of factors. It is similar to BY processing in...View answers

Questions : 11 :: What are the data structures in R that is used to perform statistical analyses and create graphs?

R has data structures like • Vectors • Matrices • Arrays • Data frames

Questions : 12 :: Explain general format of Matrices in R?

General format is Mymatrix< – matrix (vector, nrow=r , ncol=c , byrow=FALSE, dimnames = list ( char_vector_ rowname, char_vector_colnames))

Questions : 13 :: In R how missing values are represented ?

In R missing values are represented by NA (Not Available), why impossible values are represented by the symbol NaN (not a number).

Questions : 14 :: Explain what is transpose?

For re-shaping data before, analysis R provides various method and transpose are the simplest method of reshaping a dataset. To transpose a matrix or a data frame t () function is used.

Questions : 15 :: Explain how data is aggregated in R?

By collapsing data in R by using one or more BY variables, it becomes easy. When using the aggregate() function the BY variable should be in the list.

Questions : 16 :: What is the function used for adding datasets in R?

rbind function can be used to join two data frames (datasets). The two data frames must have the same variables, but they do not have to be in the same order.

Questions : 17 :: What is the use of subset() function and sample() function in R ?

In R, subset() functions help you to select variables and observations while through sample() function you can choose a random sample of size n from a dataset.

Questions : 18 :: Explain how you can create a table in R without external file?

Use the code myTable = data.frame() edit(myTable) This code will open an excel like spreadsheet where you can easily enter your data.

Questions : 19 :: How to make a great R reproducible example?

A minimal reproducible example consists of the following items : a minimal dataset, necessary to reproduce the error the minimal runnable code necessary to reproduce the error, which can be run...View answers

Questions : 20 :: How to join data frames in R (inner, outer, left, right)?

By using the merge function and its optional parameters: Inner join: merge(df1, df2) will work for these examples because R automatically joins the frames by common variable names, but you would...View answers

Questions : 21 :: How to sort a dataframe by column(s) in R?

You can use the order() function directly without resorting to add-on tools -- see this simpler answer which uses a trick right from the top of the example(order) code: R> dd[with(dd, order(-z,...View answers

Questions : 22 :: In R, why is `[` better than `subset`?

scramble <-function(x) x[sample(nrow(x)),] subscramble <-function(x, condition){ scramble(subset(x, condition))} subscramble(mtcars, cyl ==4) This returns the error: Error in...View answers

Questions : 23 :: what are the Tricks to manage the available memory in an R session?

further illustrate the common strategy of frequent restarts, we can use littler which allows us to run simple expressions directly from the command-line. Here is an example I sometimes use to time...View answers

Questions : 24 :: what are the General suggestions for debugging R?

I'd say that debugging is an art form, so there's no clear silver bullet. There are good strategies for debugging in any language, and they apply here too (e.g. read this nice article from IBM)....View answers

Questions : 25 :: How to name variables on the fly in R?

Use assign: assign(paste("orca",i,sep=""),...View answers

Questions : 26 :: How to use R's ellipsis feature when writing your own function?

data.frame uses list(...) version. Fragment of the code: object <- as.list(substitute(list(...)))[-1L] mrn <- is.null(row.names) x <- list(...) object is used to do some magic with...View answers

Questions : 27 :: How to group columns by sum in R?

Using aggregate: x <- data.frame(Category=factor(c("First", "First", "First", "Second", "Third", "Third", "Second")),...View answers

Questions : 28 :: How to do vlookup and fill down (like in excel) in R?

If I understand your question correctly, here are four methods to do the equivalent of Excel's VLOOKUP and fill down using R: # load sample data from Q hous <- read.table(header =TRUE,...View answers

Questions : 29 :: how to Convert year and month to a date in R?

Try this. (Here we use text=Lines to keep the example self contained but in reality we would replace it with the file name.) Lines <-"2009-01 12 2009-02 310 2009-03 2379 2009-04...View answers

Questions : 30 :: In R, what is the difference between the [] and [[]] notations for accessing the elements of a list?

R has three basic indexing operators, with syntax displayed by the following examples   x[i] x[i, j] x[[i]] x[[i, j]] x$a x$"a" For vectors and matrices the...View answers

Questions : 31 :: How to plot two histograms together in R?

carrots <- data.frame(length = rnorm(100000,6,2)) cukes <- data.frame(length = rnorm(50000,7,2.5))#Now, combine your two dataframes into one. First make a new column in each. carrots$veg...View answers

Questions : 32 :: How to Calculate moving average in R?

Rolling Means/Maximums/Medians in the zoo package (rollmean) MovingAverages in TTR ma in...View answers

Questions : 33 :: How to trim leading and trailing whitespace in R?

Probably the best way is to handle the trailing whitespaces when you read your data file. If you use read.csv or read.table you can set the parameterstrip.white=TRUE. If you want to clean strings...View answers

Questions : 34 :: Force R not to use exponential notation (e.g. e+10)?

This is a bit of a grey area. You need to recall that R will always invoke a print method, and these print methods listen to some options. Including 'scipen' -- a penalty for scientific display....View answers

Questions : 35 :: Painless way to install a new version of R (on Windows)?

Just for completeness, there are some ways to prevent you from having this problem. As Dirk said, save your packages in another directory on your...View answers

Questions : 36 :: How can we read command line parameters from an R script?

I made two files: exmpl.bat and exmpl.r. exmpl.bat: set R_Script="C:Program FilesR-3.0.2binRScript.exe"%R_Script% exmpl.R 2010-01-28 example 100> exmpl.batch...View answers

Questions : 37 :: How to change language settings in R?

You can set this using the Sys.setenv() function. My R session defaults to English, so I'll set it to French and then back again: > Sys.setenv(LANG ="fr")>2+ x Erreur : objet 'x'...View answers

Questions : 38 :: What is your favorite R debugging trick?

I'd say that debugging is an art form, so there's no clear silver bullet. There are good strategies for debugging in any language, and they apply here too. For instance, the first thing is to...View answers

Questions : 39 :: How to set limits for axes in ggplot2 R plots?

Basically you have two options scale_x_continuous(limits = c(-5000,5000)) or coord_cartesian(xlim = c(-5000,5000)) Where the first removes all data points outside the given range and the second...View answers

Questions : 40 :: Why are loops slow in R?

Loops in R are slow for the same reason any interpreted language is slow: every operation carries around a lot of extra baggage. Look at R_execClosure in eval.c (this is the function called to...View answers

Questions : 41 :: What ways are there to edit a function in R?

Or take a look at the debugging function trace(). It is probably not exactly what you are looking for but it lets you play around with the changes and it has the nice feature that you can always go...View answers

Questions : 42 :: How can we make xkcd style graphs in R?

You might want to consider the following package: Package xkcd: Plotting ggplot2 graphics in a XKCD style. library(xkcd) vignette("xkcd-intro") Some examples (Scatterplots, Bar...View answers

Questions : 43 :: How to Correctly Use Lists in R?

ese two expressions not return the same result? x = list(1, 2, 3, 4); x2 = list(1:4) A list can contain any other class as each element. So you can have a list where the first element is a...View answers

Questions : 44 :: How do we replace NA values with zeros in R?

> m <- matrix(sample(c(NA,1:10),100, replace =TRUE),10)> d <- as.data.frame(m) V1 V2 V3 V4 V5 V6 V7 V8 V9...View answers

Questions : 45 :: How to write trycatch in R?

urls <- c("http://stat.ethz.ch/R-manual/R-devel/library/base/html/connections.html","http://en.wikipedia.org/wiki/Xz","xxxxx") readUrl <-function(url){ out <- tryCatch({# Just to...View answers

Questions : 46 :: How to print R graphics to multiple pages of a PDF and multiple PDFs?

Usage: pdf(file = ifelse(onefile,"Rplots.pdf","Rplot%03d.pdf"), width, height, onefile, family, title, fonts, version, paper, encoding, bg, fg, pointsize, pagecentre,...View answers

Questions : 47 :: What are Replacement Functions in R?

When you call cutoff(x)<-65 you are in effect calling x <-"cutoff<-"(x = x, value =65) The name of the function has to be quoted as it is a syntactically valid but non-standard name...View answers

Questions : 48 :: In R, what exactly is the problem with having variables with the same name as base R functions?

There isn't really one. R will not normally search objects (non function objects) when looking for a function: > mean(1:10)[1]5.5> mean <-1> mean(1:10)[1]5.5> rm(mean)>...View answers

Questions : 49 :: How to parse milliseconds in R?

Courtesy of the ?strptime help file (with the example changed to your value): z <- strptime("2010-01-15 13:55:23.975","%Y-%m-%d %H:%M:%OS") z # prints without fractional seconds op...View answers

Questions : 50 :: How to see the source code of R .Internal or .Primitive function?

pnorm is C code, so the advice in the previous question view source code in R is only peripherally useful (most of it concentrates on functions hidden in namespaces etc.). Uwe Ligges's article in...View answers

Questions : 51 :: s there a R function that applies a function to each pair of columns?

It wouldn't be faster, but you can use outer to simplify the code. It does require a vectorized function, so here I've used Vectorize to make a vectorized version of the function to get the...View answers

Questions : 52 :: List some of the advantages of R.

Advantages of R: Open source Eye catching reports. Supports Data Wrangling. Quality plotting and...View answers

Questions : 53 :: What languages R is written in?

 It is mostly written in C or C++.  the work is mostly being done in a lower-level programming language like C or Fortran (Of course, since R is open source, you can take a look...View answers

Questions : 54 :: What does the R means in the R language?

 Actually, this R comes from the first 2 R author’s names, which were Ross Ihaka, Robert Gentleman. Features of R programming:- Open source Strong graphical capablities Highly active...View answers

Questions : 55 :: WHICH IS FAST R or PYTHON?

Python is faster than R, when the number of iterations is less than 1000. Below 100 steps, python is up to 8 times faster than R, while if the number of steps is higher than 1000, R beats Python...View answers

Questions : 56 :: What is the role of R in It world?

It is used in Data Analysis, Machine learning algorithms and  also used in visualising data and many more useful stuff.The R programming language is used for data analysis, data...View answers
More Question

Ask your interview questions on R

Write Your comment or Questions if you want the answers on R from R Experts
Name* :
Email Id* :
Mob no* :
Question
Or
Comment* :
 





Disclimer: PCDS.CO.IN not responsible for any content, information, data or any feature of website. If you are using this website then its your own responsibility to understand the content of the website

--------- Tutorials ---