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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!

**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?**

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!

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

The following functions are some of the many R functions –

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

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.

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.

R offers the following five Sorting Algorithms –

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

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.

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

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.

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

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

- Arrays
- Matrices
- Vectors
- Data frames

The subset() function selects variables and observations.

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

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.

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.

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

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

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

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.

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

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.

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

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

Apart from preparing for such basic R interview questions, enthusiasts can dedicate themselves to Jigsaw Academy’s 11-month Postgraduate Diploma In Data Science. This in-person course will help them achieve the necessary skill set, experience, and confidence to build a successful Data Science career.

Moreover, this course has been ranked #2 among ‘Top 10 Full-Time Data Science Courses in India’ in 2019, 2018, 2017. Lastly, it provides certification from Manipal Academy of Higher Education, a guaranteed placement policy, and much more.

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