Programming R Quiz

What does the function `install.packages()` do in R?

• It updates installed packages to the latest version.

• It installs new R packages from CRAN.

• It lists all available packages in CRAN.

• It removes specified packages from the system.

Answer explanation

The function 'install.packages()' in R installs new R packages from CRAN, making it the correct choice among the options provided.

Which function is used to read a CSV file in R?

• read.csv()

• read_excel()

• open.csv()

• file.open()

Answer explanation

The correct function to read a CSV file in R is read.csv()

How do you create a vector in R containing the numbers 1 through 5?

• c(1:5)

• vector(1, 5)

• list(1-5)

• sequence(1, 5)

Answer explanation

To create a vector in R containing the numbers 1 through 5, you use the syntax c(1:5), which generates a sequence from 1 to 5.

What symbol is used to assign a value to a variable in R?

• =

• :=

• <-

• ==

Which of the following is a way to generate a sequence of numbers from 1 to 10 in steps of 2 in R?

• seq(1, 10, by=2)

• sequence(1, 10, 2)

• 1:10+2

• c(1, 3, 5, 7, 9)

Answer explanation

The correct way to generate a sequence of numbers from 1 to 10 in steps of 2 in R is by using the 'seq(1, 10, by=2)' function.

How do you check the structure of a data frame named `df` in R?

• structure(df)

• str(df)

• typeof(df)

• describe(df)

Answer explanation

The correct way to check the structure of a data frame in R is by using the 'str(df)' function, which provides a concise summary of the data frame's structure.

What is the output of the following code snippet? ```R x <- c(TRUE, FALSE, TRUE, FALSE) sum(x) ```

• 0

• 2

• 4

• TRUE

Answer explanation

The sum of logical values in R treats TRUE as 1 and FALSE as 0. Therefore, sum(x) will result in 2.

Which function in R is used to apply a function over the margins of an array or matrix?

• lapply()

• apply()

• sapply()

• tapply()

Answer explanation

The 'apply()' function in R is used to apply a function over the margins of an array or matrix, making it the correct choice for this question.

What does the `ggplot2` package in R primarily used for?

• Data manipulation

• Statistical analysis

• Data visualization

• Machine learning

Answer explanation

The `ggplot2` package in R is primarily used for data visualization, making it the correct choice among the options provided.

How do you install multiple packages at once in R?

• install.packages(c("dplyr", "ggplot2"))

• install.packages("dplyr", "ggplot2")

• c(install.packages("dplyr"), install.packages("ggplot2"))

• install.packages("dplyr") + install.packages("ggplot2")

Answer explanation

To install multiple packages at once in R, you should use the syntax install.packages(c("dplyr", "ggplot2")). This allows you to specify multiple package names within a single function call.