R Programming Practice Test 4

1. Point out the correct statement?

2. Which of the following statement will load the objects to the file named "mydata.RData"?

3. Which of the following return a subset of the columns of a data frame?

4. The _________ function can be used to select columns of a data frame that you want to focus on.

5. When you call serialize() on an R object, the output will be ____ coded in hexadecimal format.

6. Which of the following code extracts 1st element of the 2nd element?

 > x <- list(a = list(10, 12, 14), b = c(3.14, 2.81)) 

7. If we want to save individual R objects to a file, we use the _______ function.

8. Which of the following is example of vectorized operation as far as subtraction is concerned?

> x <- 1:4
> y <- 6:9

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

 
> x <- list(foo = 1:4, bar = 0.6, baz = "hello")
> name <- "foo"
> x$name

10. Individual R objects can be saved to a file using the _____ function.