# R Interview Questions

- Data Frames
- How to “merge” data frames in R
- How do you search/replace text in a data frame
- How can you add columns to a data frame in R
- How can you add rows to a data frame in R
- How to delete columns from a data frame in R
- How to delete rows from a data frame in R
- How to remove all rows in a data frame with NAs in R
- How to remove particular values from a data frame in R
- How to remove duplicate rows from a data frame in R

- Vectors
- Graphics ( EDA )
- Data Manipulation
- Subset data
- How to subset a Dataframe
- How to subset a Vector
- How to subset a List
- How to subset a Matrix

- Data Structures
- What are the basic data structures in R
- What is the difference between dataframe and matrix
- How to find out the unique elements in a vector
- What is the difference between data frame and data table
- What is the difference between a dataframe and a list

- Commonly used Statistics functions
- How is skewness of a distribution calculated in R
- How is kurtosis of a distribution calculated in R
- How do you calculate mean, median, MAD and SD in R
- How to get correlation matrix (or coefficients) for a set of variables in R
- How to generate the same set of random numbers in R
- What is the difference between runif () and rnorm () functions in R
- How to get samples from a data set
- What is confusion matrix

- Packages
- Data Loading
- Data Cleansing
- Modularization
- How to split your program across multiple files in R
- How to write a function in R

- Functions
- What is the use of … ( ellipsis ) in functions in R
- How to write recursive functions in R
- How to specify default values in function parameters in R
- How to see the source code of a function in R

- Version Management
- ML – Regression
- How to do Linear Regression in R
- How to do multi linear regression in R
- How do you specify the formula for a logarithmic regression in R
- How to you specify powers in polynomial regression formula
- How did you split the data into training and test data
- What plots in R did you produce to communicate your linear regression test results
- What packages did you use in R to find out significant variables in multi linear regression

- ML – Classification
- What packages did you use for KNN classification in R
- How to do confusion matrix in R

- What packages did you use for KNN classification in R