**31. What is R Base package?**

This is the package which is loaded by default when R environment is set. It provides the basic functionalities like input/output, arithmetic calculations etc. in the R environment.

**32. What is the reshaping of data in R?**

In R the data objects can be converted from one form to another. For example, we can create a data frame by merging many lists. This involves a series of R commands to bring the data into the new format. This is called data reshaping.

**33. What is the use of “next” statement in R?**

The “next” statement in R programming language is useful when we want to skip the current iteration of a loop without terminating it.

**34. Write a function in R language to replace the missing value in a vector with the mean of that vector.**

mean impute <- function(x) {x [is.na(x)] <- mean(x, na.rm = TRUE); x}

**35. How can you verify if a given object “X” is a matrix data object?**

If the function call is.matrix(X) returns true then X can be considered as a matrix data object otherwise not.

**36. What is the use of sample and subset functions in R programming language?**

- Sample () function can be used to select a random sample of size ‘n’ from a huge dataset.
- Subset () function is used to select variables and observations from a given dataset.

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

It is used to apply the same function to each of the elements in an Array. For example, finding the mean of the rows in every row.

**38. What is expected from running the command – strsplit(x,”e”)?**

It splits the strings in vector x into substrings at the position of letter e.

**39. What is the difference between the library() and require() functions in R language?**

There is no real difference between the two if the packages are not being loaded inside the function. require () function is usually used inside the function and throws a warning whenever a particular package is not found. On the flip side, library () function gives an error message if the desired package cannot be loaded.

**40. How will you list all the datasets available in all R packages?**

Using the below line of code –

data(package = .packages(all.available = TRUE))