R Programming Online Test

1. _______ is discovering unseen patterns from data.

2. Computation with vectors is achieved using an element-by-element operation for avoiding _________

3. If a programmer wants the output to be a list then ___________ function is used.

4. The __________ package has functionality to investigate transformations of univariate distributions.

5. What will be the output of the following R code?

 
> set.seed(20)
> x <- rnorm(100)
> e <- rnorm(100, 0, 2)
> y <- 0.5 + 2 * x + e 
> summary(y)

6. Which function is used to enter in data at the terminal?

7. The first component can be accessed using __________ operator.

8. Point out the correct statement?

9. system.time function returns an object of class _______ which contains two useful bits of information.

10. __________are Data frames which contain lists of homogeneous data in a tabular format.

11. Which of the following is the formal requirement?

12. Which of the following finds row sums for each level of a grouping variable?

13. Point out the wrong statement?

14. Which of the following functions is typically used to add elements to a plot in the base graphics system?

15. A single element of a character vector is referred as ________

16. In the base graphics system, which function is used to add elements to a plot?

17. Which of the following lists names of variables in a data.frame?

18. _________ are mostly used for statistical analysis.

19. What will be the output of the following R code?

> x <- 6
> class(x)

20. The benefit of the _____ function is that it is the only way to perfectly repressed an R object in an exportable format, without losing precision or any metadata.

21. Which of the following function is similar to summarize?

22. Which of the following is primary tool for debugging?

23. Which of the following R syntax is correct for while loop?

24. R runs on the ____________ operating system.

25. We can dump() R objects to a file by passing _____

26. If the programmers want the output to be a data frame or a vector, then ________ function is used.

27. Which function is used for seeing currently active libraries?

28. In the expression x <- 4 in R, what is the class of 'x' as determined by the `class()' function?

29. Why is it needed for R studio to update regularly?

30. What will be the output of the following R code?

> x <- data.frame(foo = 1:4, bar = c(T, T, F, F))
> ncol(x)

31. What will be the output of the following R code?

> f <- function(num) {
+ for(i in seq_len(num)) {
+               cat("Hello, world!\n")
+ }
+ }
> f(3)

32. Which of the following is default prompt for UNIX environment?

33. Which of the following contains functions for processing uniaxial minute-to-minute accelerometer data?

34. What will be the output of the following R code?

> g <- function(x) {
+               a <- 3
+               x+a+y
+             ## 'y' is a free variable
+ }
> y <- 3
> g(2)

35. ______ regression method is also known as the ordinary least squares estimation.

36. Point out the wrong statement?

37. The empirical cumulative distribution function can be called as __________

38. Point out the correct statement?

39. ________ allows you to insert debugging code into a function a specific places

40. ________ is used for relative sizing of theme elements.

41. Write the syntax to set the path of the current working directory in R environment?

42. The most convenient way to use R is at a graphics workstation running a ________ system.

43. __________ function is used in applying a function each level of factors.

44. What will be the output of the following R code?

> x <- matrix(1:4, 2, 2)
> y <- matrix(rep(10, 4), 2, 2)
> x * y

45. ______ let's you perform SQL queries on your R data frames.

46. Which of the following is complementary to tidyr?

47. Which of the following groups values of a variable into larger bins?

48. The dplyr package can be installed from CRAN using __________

49. Point out the correct statement?

50. Which of the following can be used to display the names of (most of) the objects which are currently stored within R?