Homework 3

Published

February 17, 2023

Due 2/24/23 @ 11:59 PM

Use an RMD Notebook file from to create the assignment.

You must comment all your code to receive credit.

Submit the *nb.html file to canvas.

Problem 1

Using the vectors below, use sapply() to determine if the numbers are even or odd.

x <- 1:20

Problem 2

Evaluate the following function:

\[ k(j(i(h(g(f(x)))))) \]

  • \(f(x)=\sin(x)\)

  • \(g(x) = x^2 +5\)

  • \(h(x) = \exp{2x}\)

  • \(i(x) = \sin(\pi x)\)

  • \(j(x) = x^2 + 5\)

  • \(k(x) = \sqrt x\)

You are not allowed to store values, but you may create and store functions.

Problem 3

From the penguins data set from palmerpenguins package, create a new variable indicating if the penguin’s flipper length (flipper_length_mm) is greater than the average flipper length. Afterwards, group by the new variable and find the mean body_mass_g.

Problem 4

From the penguins data set from palmerpenguins package, find the mean and standard deviation of flipper_length_mm by species.

Problem 5

Using the vector random_dates generated from the code below:

# Set the start and end dates
start_date <- as.POSIXct("2022-01-01 00:00:00")
end_date <- as.POSIXct("2022-12-31 23:59:59")

# Generate a vector of random dates and times between the start and end dates
random_dates <- as.POSIXct(runif(10, start_date, end_date), origin = "1970-01-01")

# Print the vector of random dates and times
random_dates

Use sapply() to determine what day of the week (in words) does the date represent. Hint: Look at the wday function from lubridate.