# Top 20 R Interview Questions

**Introduction To R**

If you’re up-to-date with the programming world, you might have often heard about the R language from various sources. So, what is this language all about?

R is an open-source programming language. Its implementation includes Data Visualization, Statistical Analysis, Forecast Analysis, Predictive Modeling, Data Manipulations, and many more.

Enormous businesses like Facebook, Google, Twitter, etc., make use of the R language. This article provides a compilation of the top 20 R interview questions that applicants must know before applying for job interviews!

**Contents At A Glance **

**List Of Top 20 R Interview Questions**

**1. Can you mention a few functions that R provides?**

**2. What are the points of difference between Python and R?**

**3. How can you import data in R?**

**4. How many Sorting Algorithms does R offer?**

**5. Can you list some disadvantages of R Programming?**

**6. Which function adds datasets in R language?**

**7. What are the steps to save data in R?**

**8. How can we start the R commander GUI? What is the command for this purpose?**

**9. Which data structures help perform Statistical Analyses and create graphs in R?**

**10. What is the use of the subset() method in R?**

**11. What is the use of the sample() function in R?**

**12. How can you create a table in R without using an external file?**

**14. Which variable should we use while working with the aggregate() method?**

**15. How to represent missing values in R?**

**16. How to represent impossible values in R?**

**17. What is t-test() in R programming language?**

**18. How can you produce co-relations and covariances in R?**

**19. What is the memory limit of R?**

**20. What does the coin package in R do?**

**Definition Of R Language**

Before we get to the R language interview questions, let us first examine the R language definition.

R is a free software environment and a programming language as well. It involves Statistical Computing and Graphics.

Statisticians and Data Miners extensively implement R for developing statistical software and Data Analysis. It is a popular programming language. As of September 2020, R holds the 9th rank in the TIOBE index. The TIOBE index estimates the popularity of programming languages.

Let us now examine the top 20 interview questions in R!

**List Of Top 20 R Interview Questions**

The following is a list of 20 R basic interview questions that prepare interviewees for their interviews.

**1. Can you mention a few functions that R provides?**

The following functions are some of the many R functions –

- Mean
- Median
- Distribution
- Covariance
- Regression
- Non-linear

**2. What are the points of difference between Python and R?**

Even though Python and R have a similar model, there is a significant difference between them. For instance, R has a better Model Interpretability than Python. On the other hand, Python provides better Production. When it comes to Community Support, R has the upper hand over Python. Moreover, R offers excellent Data Visualization Libraries and Tools. Nonetheless, Python is more comfortable to learn compared to the R language.

**3. How can you import data in R?**

To import data in R, we use the R commander. Using any of the following three ways, we can successfully import data –

- We can select the data set in the dialog box or enter the desired data set’s name.
- To import a small-sized data set, we can use the R Commander’s editor via Data -> New Data Set.
- Lastly, we can import data from a URL, a plain text file (ASCII), a statistical package, or the clipboard.

**4. How many Sorting Algorithms does R offer?**

R offers the following five Sorting Algorithms –

- Bubble Sort
- Selection Sort
- Merge Sort
- Quick Sort
- Bucket Sort

**5. Can you list some disadvantages of R Programming?**

The disadvantages of using R are below –

- R lacks standard GUI.
- R is not suitable for Big Data.
- R does not offer a spreadsheet view for data.

** 6. Which function adds datasets in R language?**

The rbind() function joins two datasets. They must have the same variables, but they do not have to be in the same order.

**7. What are the steps to save data in R?**

We can use diverse methods to save data in R, but the most straightforward approach is as follows –

Go to Data -> Active Data Set -> Export Active Data Set

Here, a dialogue box will appear. Click ‘ok’ on the dialogue box to save your data.

**8. How can we start the R commander GUI? What is the command for this purpose?**

To start the R commander GUI, type the command – Rcmdr – into the R console.

**9. Which data structures help perform Statistical Analyses and create graphs in R?**

Some data structures that R uses for Statistical Analyses and creation of graphs –

- Arrays
- Matrices
- Vectors
- Data frames

**10. What is the use of the subset() method in R?**

The subset() function selects variables and observations.

**11. What is the use of the sample() function in R?**

The sample() function chooses a random sample of size n from a dataset.

**12. How can you create a table in R without using an external file?**

The following code helps us to create a table in R without using an external file –

mytable = data.frame()

edit(mytable)

This code will open a spreadsheet to enter your data quickly.

**13. What is transpose?**

R provides various methods to re-shape data before analysis, and transpose is the simplest of them all. To transpose a matrix or a data set, we use the t() function.

**14. Which variable should we use while working with the aggregate() method?**

When using the aggregate() function, we should use the BY variable.

**15. How to represent missing values in R?**

In R, NA (Not Available) represents missing values.

**16. How to represent impossible values in R?**

To represent the impossible values, R uses NaN (not a number).

**17. What is t-test() in R programming language?**

The t.test() function creates various t-tests. In Statistics, a T-test is the most common test determining if the means of the required two groups are equal.

**18. How can you produce co-relations and covariances in R?**

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

**19. What is the memory limit of R?**

In a 32-bit system, the memory limit is 3Gb, but most versions are limited to 2Gb. In a 64-bit system, the memory limit of R is 8Tb.

**20. What does the coin package in R do?**

Coin package helps achieve the Re-randomization or Permutation-based Statistical tests.

**Conclusion**

R is a programming language with multiple implementations. Understanding these interview questions on R help learners to increase their chances of getting hired.

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