Basic R Programs for Beginners

Basic R Programs for Beginners - Important Points

6.		What is the output of the following R code snippet? x <- c(1, 2, 3, 4, 5) y <- c(2, 3, 4) z <- x[!x %in% y] print(z)

What is the output of the following R code snippet?

x <- c(1, 2, 3, 4, 5)
y <- c(2, 3, 4)
z <- x[!x %in% y]
print(z)

A. 1 2 3

B. 1 5

C. 2 3 4

D. 4 5

View Answer Discuss Work Space

Answer: option b

Explanation:

The code defines two vectors x and y, then uses the %in% operator to check which elements of x are also present in y, negates the result using the ! operator, and selects the elements of x that are not in y using square brackets. The resulting vector is [1 5].

7.		What is the output of the following R code snippet? x <- 1 while (x < 5) { print(x) x <- x + 1 }

What is the output of the following R code snippet?

x <- 1
while (x < 5) {
print(x)
x <- x + 1
}

A. 1 2 3 4

B. 2 3 4 5

C. 1 2 3 4 5

D. Error

View Answer Discuss Work Space

Answer: option a

Explanation:

The code uses a while loop to repeatedly print the value of x as long as x is less than 5, and increments x by 1 in each iteration. The loop executes 4 times and prints the values 1, 2, 3, 4.

8.		What is the output of the following R code snippet? x <- 1 for (i in 1:5) { x <- x * i } print(x)

What is the output of the following R code snippet?

x <- 1
for (i in 1:5) {
x <- x * i
}
print(x)

A. 5

B. 24

C. 120

D. 720

View Answer Discuss Work Space

Answer: option c

Explanation:

The code uses a for loop to multiply x by the integers from 1 to 5 and store the result back in x. After the loop completes, x contains the product of the integers from 1 to 5, which is 120.

9.		What is the output of the following R code snippet? x <- c(1, 2, 3, 4, 5) y <- c("one", "two", "three", "four", "five") z <- data.frame(x, y) subset(z, x %% 2 == 0)

What is the output of the following R code snippet?

x <- c(1, 2, 3, 4, 5)
y <- c("one", "two", "three", "four", "five")
z <- data.frame(x, y)
subset(z, x %% 2 == 0)

A. A data frame with two columns: x and y, with the rows where x is even.

B. A data frame with two columns: x and y, with the rows where y is even.

C. A data frame with two columns: x and y, with the rows where both x and y are even.

D. Error

View Answer Discuss Work Space

Answer: option a

Explanation:

The code defines two vectors x and y, then combines them into a data frame using the data.frame function. The subset function is used to select only the rows of the data frame where x is even, resulting in a data frame with two columns: x and y, containing the rows where x is even.

10.		What is the output of the following R code snippet? x <- c(1, 2, 3, 4, 5) y <- c("one", "two", "three", "four", "five") z <- data.frame(x, y) z$y <- as.factor(z$y) levels(z$y)

10.

What is the output of the following R code snippet?

x <- c(1, 2, 3, 4, 5)
y <- c("one", "two", "three", "four", "five")
z <- data.frame(x, y)
z$y <- as.factor(z$y)
levels(z$y)

A. 1 "2" "3" "4" "5"

B. one "two" "three" "four" "five"

C. five "four" "one" "three" "two"

D. Error

View Answer Discuss Work Space

Answer: option c

Explanation:

The code defines two vectors x and y, then combines them into a data frame using the data.frame function. The as.factor function is used to convert the y column to a factor, which creates levels for each unique value of y. The levels function is used to extract the levels of the y factor, which are the original character values "five" "four" "one" "three" "two".

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