Kimberly Cook

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R programming language interview answers data analysis data scientist

R Programming Language: 35 Job Interview Questions and Answers

By Kimberly Cook |Email | Nov 21, 2018 | 3816 Views

1) Explain what is R?
R programming language is data analysis software which is used by analysts, quants, statisticians, data scientists, and others.

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. etc.
3) Explain how you can start the R commander GUI?

Typing the command, ("Rcmdr") into the R console starts the R Commander GUI.

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 plain text (ASCII) or other files (SPSS, Minitab, etc.)
  • Read a dataset either by typing the name of the data set or selecting the data set in the dialog box

5) Mention what does not â??Râ?? language do?
  • Though R programming can easily connect to DBMS is not a database
  • R does not consist of any graphical user interface
  • Though it connects to Excel/Microsoft Office easily, R language does not provide any spreadsheet view of data
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
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 DataSet and a dialogue box will appear, when you click ok the dialogue box lets you save your data in the usual way.

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.

9) Explain what is t-tests in R?

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

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

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

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

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

12) Explain the 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))

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).

14) Explain what is transpose?

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

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.

16) What is the function used for adding datasets in R?
The 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.

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.

18) Explain how you can create a table in R without the external file?

Use the code

myTable = data.frame()
edit(myTable)


Second Set
  1. Data structure -- How many data structures R has? How do you build a binary search tree in R? 
  2. Sorting -- How many sorting algorithms are available? Show me an example in R. 
  3. Low level -- How do you build an R function powered by C? 
  4. String -- How do you implement string operation in R?
  5. Vectorization -- If you want to do Monte Carlo simulation by R, how do you improve the efficiency? 
  6. Function -- How do you take a function as an argument of another function? What is the apply() function family? 
  7. Threading -- How do you do multi-threading in R? 
  8. Memory limit and database -- What is the memory limit of R? How do you avoid it? How do you use SQL in R? 
  9. Testing -- How do you do testing and debugging in R?
  10. Software development -- How do you develop a package? How do you do version control?
You can find the answers here.

Third Set 


Other R questions are posted here. 

Source: HOB
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