Control Structures in R Programming MCQ question and answer with solution

31

A function, together with an environment, makes up what is called a . . . . . . . . closure.

A) formal B) function C) reflective D) symmetry

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Answer & Solution

Answer: Option B

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32

Body of lapply function is?

A)

function (X, FUN, ...)
{
    FUN <- match.fun(FUN)
    if (!is.vector(X) || is.object(X))
       X <- as.list(X)
    .Internal(lapply(X, FUN))
}

B)

function (X, FUN, ...)
{
    FUN <- match.fun(FUN)
    if (!is.vector(X) | is.object(X))
      X <- as.list(X)
    .Internal(lapply(X, FUN))
}

C)

function (X, FUN, ...)
{
    FUN <- match.fun(FUN)
    if (is.vector(X) || is.object(X))
      X <- as.list(X)
    .Internal(lapply(X, FUN))
}

D)

function (X, FUN, ...)
{
    FUN <- match.fun(FUN)
    if (is.vector(X) || is.object(X))
}

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Answer & Solution

Answer: Option A

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33

. . . . . . . . is used to break the execution of a loop.

A) next B) skip C) break D) delete

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Answer & Solution

Answer: Option C

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34

Write a function to extract the first name in the string "Mrs. Jake Luther"?

A) Substring B) Substr C) Substi D) Return

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Answer & Solution

Answer: Option B

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35

Which of the following R code will print the following result?

[[1]]
[1] 2.263808
[[2]]
[1] 1.314165 9.815635
[[3]]
[1] 3.270137 5.069395 6.814425
[[4]]
[1] 0.9916910 1.1890256 0.5043966 9.2925392

A) > x <- 1:4
> lapply(x, runif, min = 0, max = 10) B) > x <- 1:4
> lapply(x, runif, min = 0, max = 9) C) > x <- 1:3
> lapply(x, runif, min = 0, max = 10) D) > x <- 1:4
> lapply(x, runif, min = 0, max = 6)

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Answer & Solution

Answer: Option A

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36

What will be the output of the following R code?

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

A) 32 B) 42 C) 52 D) 46

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Answer & Solution

Answer: Option A

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37

. . . . . . . . function is same as lapply in R.

A) apply() B) lapply() C) sapply() D) mapply()

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Answer & Solution

Answer: Option C

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38

What would be the value of following R expression?

log(-1)

A) Warning in log(-1): NaNs produced B) 1 C) Null D) 0

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Answer & Solution

Answer: Option A

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39

The . . . . . . . . for R are the main feature that make it different from the original S language.

A) scoping rules B) closure rules C) environment rules D) closure & environment rules

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Answer & Solution

Answer: Option A

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40

What will be the output of the following R code?

> f <- function(elt) {
+ elt[, 1]
+ }
> lapply(x, f)

A) $a
[1] 1 2
$b
[1] 1 2 3 B) $a
[1] 1 2 3
$b
[1] 1 2 3 C) $a
[1] 1 2 3
$b
[1] 1 2 D) Error

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Answer & Solution

Answer: Option A

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