R interview questions part 4
R interview questions part 4
Take as many assements as you can to improve your validate your skill rating
Total Questions: 20
1. which of the following statement gives cumulative sum ?
Correct Answer is : cumsum(x,na=rm=TRUE)
2. Which of the following is uniform distribution ?
Correct Answer is : dunif(x, min=0, max=1, log = FALSE)
3. Which of the following truncates real x to integers ?
Correct Answer is : as.integer(x)
4. Which of the following tests each element of x for membership in y?
Correct Answer is : x%in%y
5. Which of the following finds the maximum value in the vector x, exclude missing values
Correct Answer is : max(x, na.rm=TRUE)
6. Which of the following produces the variance covariance matrix ?
Correct Answer is : var(x, na.rm=TRUE)
7. Which of the following will reverse the order of values in x ?
Correct Answer is : rev(x)
8. Which of the following finds row sums for each level of a grouping variable ?
Correct Answer is : rowMeans(x, na.rm = FALSE, dims = 1)
9. Which of the following statement applies the function (FUN) to either rows (1) or columns (2) on object X ?
Correct Answer is : apply(X, MARGIN, FUN, …)
10. Which of the following statement finds the maximum for each column ?
Correct Answer is : apply(x,2,max)
11. which of the following statement tells the row with the minimum value for every column ?
Correct Answer is : which.min(x)
12. Which of the following may be used for linear regression ?
Correct Answer is : solve(A,B)
13. Which of the following finds row sums for each level of a grouping variable ?
Correct Answer is : rowsum(x, group, reorder = TRUE, …)
14. Which of the following sets the size of the outer margins for the graph ?
Correct Answer is : par(omi=c(0,0,1,0) )
15. Which of the following function is used for plotting histogram ?
Correct Answer is : hist()
16. Which of the following will add the title “R language” to the graph ?
Correct Answer is : title( “R language”)
17. Individual R objects can be saved to a file using the _____ function.
Correct Answer is : save
18. Point out the correct statement :
Correct Answer is : All of the mentioned
19. Which of the following statement will save the output to the file for following code ? > a <- data.frame(x = rnorm(100), y = runif(100)) > b <- c(3, 4.4, 1 / 3)
Correct Answer is : save(a, b, file = “mydata.rda”)
20. Which of the following statement will load the objects to the file named “mydata.RData” ?
Correct Answer is : load(“mydata.RData”)
