Data Structures in R Programming MCQ question and answer with solution

71

Which of the following code would read 100 rows?

A) initial <- read.table("datatable.txt", nrows = 100) B) tabAll <- read.table("datatable.txt", colClasses = classes) C) initial <- read.table("datatable.txt", nrows = 99) D) initial <- read.table("datatable.txt", nrows = 101)

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Answer & Solution

Answer: Option A

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72

Point out the correct statement?

A) The data frame is a key data structure in statistics and in R B) R has an internal implementation of data frames that is likely the one you will use most often C) There are packages on CRAN that implement data frames via things like relational databases that allow you to operate on very very large data frames D) All of the mentioned

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Answer & Solution

Answer: Option D

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73

Which of the following code opens a connection to the file foo.txt, reads from it, and closes the connection when its done?

A) data <- read.csv("foo.txt") B) data <- read.csvo("foo.txt") C) data <- readonly.csv("foo.txt") D) data <- getonly.csv("foo.txt")

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Answer & Solution

Answer: Option A

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74

Point out the wrong statement?

A) Dates are represented by the Date class B) Times are represented by the POSIXct or the POSIXlt class C) Dates are represented by the DateTime class D) Times can be coerced from a character string

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Answer & Solution

Answer: Option C

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75

What will be the output of the following R code?

> x <- c(1, 2, NA, 4, NA, 5)
> bad <- is.na(x)
> print(bad)

A) FALSE FALSE FALSE FALSE TRUE FALSE B) FALSE TRUE TRUE FALSE TRUE FALSE C) FALSE FALSE TRUE FALSE TRUE FALSE D) FALSE TRUE TRUE TRUE TRUE FALSE

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Answer & Solution

Answer: Option C

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76

Point out the correct statement?

A) unserialize is used for converting an R object into a binary format for outputting to a connection B) save is used for saving an arbitrary number of R objects in binary format to a file C) The read.data() function is one of the most commonly used functions for reading data D) save is not used for saving an arbitrary

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Answer & Solution

Answer: Option B

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77

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

A) save("mydata.RData") B) load("mydata.RData") C) loadAll("mydata.RData") D) put("mydata.RData")

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Answer & Solution

Answer: Option B

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78

. . . . . . . . opens a connection to a file compressed with gzip.

A) url B) gzfile C) bzfile D) file

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Answer & Solution

Answer: Option B

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79

What will be the output of the following R code?

> y <- data.frame(a = 1, b = "a")
> dput(y)

A)

structure(list(a = 1, b = list(1L, .Label = "a", class = "factor")), .Names\
= c("a",
"b"), row.names = c(NA, -1L), class = "data.frame")

B)

list(list(a = 1, b = list(1L, .Label = "a", class = "factor")), .Names\
= c("a",
"b"), row.names = c(NA, -1L), class = "data.frame")

C)

structure(list(a = 1, b = structure(1L, .Label = "a", class = "factor")), .Names\
= c("a",
"b"), row.names = c(NA, -1L), class = "data.frame")

D) Error

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Answer & Solution

Answer: Option C

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80

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

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

A) x+y B) x-y C) x/y D) y/x

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Answer & Solution

Answer: Option B

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Data Structures in R Programming MCQ question and answer with solution | R Programming MCQs