**R Programming Interview Questions for freshers experienced :-**

**1. What is R programming language?**

R is an open source programming language. It is software environment for statistical computing and graphics. It compiles and runs on a wide variety of UNIX platforms, Windows and MacOS.

**2. Who is the developer of R programming language?**

R Core Team is the developer of R programming language.

**3. What is the stable version of R programming language?**

The stable version of R programming language is 3.4.1 and released on 30 June 2017 .

**4. In which language R programming language was written?**

R programming language was written in C and Fortran language.

**5. How to create a simple program in R programming Language?**

The following code to create a simple program is:

# Print Hello World.

print(“Hello World”)

# Add two numbers.

print(23.9 + 11.6)

**6. What are the features of R programming language?**

R programming language features are given below:

- It is simple and effective programming language.
- It has an effective data handling and storage facility.
- It provides large collection of tools.
- It provides graphics facilities.

**7. What are the disadvantages of R Programming?**

The disadvantages of R programming are:-

- Lack of standard GUI
- Not good for big data.
- Does not provide spreadsheet view of data.

**8. How to write comment in single line?**

# symbol is used to write comment in single line,

Example:

# My first program in R Programming

**9. What is operator and its type?**

An Operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations.

The following types of operator:

- Arithmetic Operators
- Relational Operators
- Logical Operators
- Assignment Operators
- Miscellaneous Operators

**10. What is R environment?**

R environment is used for data manipulation, calculation and graphical display. It includes:

- an effective data handling and storage facility.
- a suite of operators for calculations on arrays, in particular matrices.
- a large, coherent, integrated collection of intermediate tools for data analysis.
- graphical facilities for data analysis and display either on-screen or on hardcopy.

**11. What are the types of control statement?**

There are following control statement:

- Break statement
- Next statement

**12. How to declare the function in R programming language?**

In R programming language, the function is declared by using function keyword.

function_name <- function(arg_1, arg_2, …) {

Function body

}

**13. What is the use of nchar() function in R programming language?**

In R programming language, nchar function is used to count the number of character including space.

**14. What are the types of vectors in R programming language?**

There are following types of vector in R programming language:

- Logical
- Integer
- Double
- Complex
- Character
- Raw

**15. What is factor in R programming language?**

In R programming language, factors are the data objects that used to categorize the data and store it as levels.

**16. What are the features of data frame?**

There are following features of data frame:

- The column names should be non-empty.
- The row names should be unique.
- The data stored in a data frame and it can be of numeric and character type.
- Each column should contain same number of data items.

**17. What do you mean by Data Reshaping in R programming language?**

In R programming language, Data Reshaping is the way to change the data into rows and columns.

**18. What are the various functions in R programming language?**

The various functions of R programming language are given below:

- Mean
- Median
- Distribution
- Covariance
- Regression
- GLM etc

**19. What is the use of mean() method in R programming language.**

In R programming language, mean() method is used to calculate the sum of the value and dividing the number of the value in a data series.

Syntax:

mean(x, trim = 0, na.rm = FALSE, …)

**20. What is the use of With () and By () function in R programming language?**

The use of following function is:

- With() : It is used to apply an expression to a dataset.
- BY() : It is used to apply a function to each level of factors.

**21. What is the use of apply() method in R?**

It is used to apply the same function to each of the elements in an Array.

**22. How to write general format of matrices in R?**

The following codes for general format of matrix are:

Mymatrix< matrix (vector, nrow=r , ncol=c , byrow=FALSE,

dimnames = list ( char_vector_ rowname, char_vector_colnames))

**23. What is the difference between R and python language?**

The following given difference R and python language:

**R programming language****Python programming language**- Model building is similar to Python. Model Building is similar to R.
- Model interpretability is good. Model Interpretability is not good
- It has community support over Python. Data visualization is not better than R
- It has a steep learning curve. Learning Curve in Python is easier than learning R.
- It has good data visualizations libraries and tools Data visualization is not better than R

**24. What is linear regression in R programming language?**

**25. In R programming language, linear regression is statistical tool to establish a relationship model between two variables.**