Data Structures In R Programming — Part 2 MCQs with Explanations

a b 1 1 a is the correct answer to “Which of the following is used for reading tabular data? > y <- data.frame(a = 1, b = "a") > dput(y, file = "y.R") > new.y <- dget("y.R") > new.y”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

dput is the correct answer to “. . . . . . . . is used for outputting a textual representation of an R object.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

read.csv is the correct answer to “Which of the following function is identical to read .table”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

"POSIXct" "POSIXt" is the correct answer to “What will be the output of the following R code? > x <- Sys.time() > class(x)”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

filter is the correct answer to “. . . . . . . . function is similar to the existing subset() function in R but is quite a bit faster.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

load is the correct answer to “Which of the following is used for reading in saved workspaces”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

FALSE FALSE TRUE TRUE is the correct answer to “What will be the output of the following R code? > x <- 1:4 > x > 2”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

group_by() is the correct answer to “Which of the following function is similar to summarize”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

pipe is the correct answer to “The . . . . . . . . operator is used to connect multiple verb actions together into a pipeline.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

"1970-01-01" is the correct answer to “What will be the output of the following R code? > x <- as.Date("1970-01-01") > x”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

mutate is the correct answer to “. . . . . . . . add new variables/columns or transform existing variables.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

file is the correct answer to “Connections to text files can be created with the . . . . . . . . function.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

save and save.image functions is the correct answer to “.rda extension used when saving data with function . . . . . . . .”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

[,1] [,2] [1,] 10 30 [2,] 20 40 is the correct answer to “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”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

con <- file("foo.txt") is the correct answer to “Which of the following R code creates a connection to 'foo.txt'”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

devtools is the correct answer to “The dplyr package can be installed from GitHub using the . . . . . . . . package.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

source() is the correct answer to “Multiple objects can be de parsed at once and read back using function . . . . . . . .”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

Time difference of 2 days is the correct answer to “What will be the output of the following R code? > x <- as.Date("2012-03-01") > y <- as.Date("2012-02-28") > x-y”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

con <- gzfile("words.gz") is the correct answer to “Which of the following opens connection to gz-compressed text file”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

$foo [1] 1 2 3 4 $bar [1] 0.6 is the correct answer to “What will be the output of the following R code? > x <- list(foo = 1:4, bar = 0.6) > x”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

select is the correct answer to “The . . . . . . . . function can be used to select columns of a data frame that you want to focus on.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

14 is the correct answer to “What will be the output of the following R code? > x <- list(a = list(10, 12, 14), b = c(3.14, 2.81)) > x[[c(1, 3)]]”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

1 is the correct answer to “What will be the output of the following R code? > p <- as.POSIXlt(x) > names(unclass(p)) > p$wday”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

DBI is the correct answer to “There is an SQL interface for relational databases via the . . . . . . . . package.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

R code is the correct answer to “dput() output is in the form of . . . . . . . .”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

metadata is the correct answer to “Unlike writing out a table or CSV file, dump() and dput() preserve the . . . . . . . . so that another user doesn't have to specify the all over again.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

initial <- read.table("datatable.txt", nrows = 100) is the correct answer to “Which of the following code would read 100 rows”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

data <- read.csv("foo.txt") is the correct answer to “Which of the following code opens a connection to the file foo.txt, reads from it, and closes the connection when its done”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

FALSE FALSE TRUE FALSE TRUE FALSE is the correct answer to “What will be the output of the following R code? > x <- c(1, 2, NA, 4, NA, 5) > bad <- is.na(x) > print(bad)”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

load("mydata.RData") is the correct answer to “Which of the following statement will load the objects to the file named "mydata.RData"”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

gzfile is the correct answer to “. . . . . . . . opens a connection to a file compressed with gzip.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

structure(list(a = 1, b = structure(1L, .Label = "a", class = "factor")), .Names\ = c("a", "b"), row.names = c(NA, -1L), class = "data.frame") is the correct answer to “What will be the output of the following R code? > y <- data.frame(a = 1, b = "a") > dput(y)”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

x-y is the correct answer to “Which of the following is example of vectorized operation as far as subtraction is concerned? > x <- 1:4 > y <- 6:9”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

3 is the correct answer to “What will be the output of the following R code? > x <- matrix(1:6, 2, 3) > x[1, 2]”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

save is the correct answer to “Individual R objects can be saved to a file using the . . . . . . . . function.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

save.image() is the correct answer to “If you have a lot of objects that you want to save to a file, we use . . . . . . . . function.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

dput() is the correct answer to “Multiple objects can be de parsed at once using the . . . . . . . . function.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

raw vector is the correct answer to “When you call serialize() on an R object, the output will be . . . . . . . . coded in hexadecimal format.”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

x[[c(2, 1)]] is the correct answer to “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))”. This question is standard in competitive examination syllabi for Data Structures In R Programming.

filter is the correct answer to “Which of the following object is masked from 'package: stats'”. This question is standard in competitive examination syllabi for Data Structures In R Programming.