Lab 04

Directions

For this lab, you will create a single .R file called lab04.R. The following exercises will ask you to write code. Place all requested code in this .R file separated by comments which indicate which code corresponds to which exercise.

Note: Do not write your name or netID anywhere in the file or in the filename. To the best of our ability, we will try to grade labs anonymously.

Submit your lab to the corresponding assignment on Canvas. You have unlimited attempts before the deadline. Your final submission before the deadline will be graded.

Grading

This lab will be graded based on a mix of correctness and completion. Each exercise is worth two points. For each exercise that you demonstrate a good-faith effort to complete, you will receive at least one point. Because there are only three exercises, by turning in the lab you will start with four points.

Exercise 1 (Fizz Buzz)

Write a function called fizz_buzz. The function will take a single argument x which is a numeric vector of any length.

The function should return a character vector of the same length as the input x that is a modification of x in the following ways:

If an element of x is a multiple of 3, replace it with "fizz".
If an element of x is a multiple of 5, replace it with "buzz".
If an element of x is both a multiple of 3 and a multiple of 5, replace it with "fizzbuzz".

This vector will contain a mix of “numbers” and characters, so any numbers not replaced by "fizz", "buzz", or "fizzbuzz", will need to be characters like "42".

To demonstrate that your code is correct, also run (and place in your .R file) the following lines after writing your function:

fizz_buzz(x = 1:5)
fizz_buzz(x = 10:20)

Note, the following will be useful:

1:10 %% 3

##  [1] 1 2 0 1 2 0 1 2 0 1

The %% operator is used to do modular arithmetic. In particular, when the above code returns 0, those elements of 1:10 are divisible by 3.

Exercise 2 (Leap Years)

Write a function called is_leap that takes as input a numeric vector of length one named year that stores a year. (For simplicity, assume only integer values greater than 0 are used.)

Leap years occur:

on every year that is evenly divisible by 4
- except every year that is evenly divisible by 100
  - unless the year is also evenly divisible by 400

Your function should output TRUE if year is a leap year, FALSE otherwise.

In addition to your function, run it at least five times with different inputs to verify that it works. Include this in your .R file.

Exercise 3 (Multiplicative Sequences)

Write a function called gen_mult_seq that has three arguments:

first: a numeric vector of length one
multi: a numeric vector of length one
length: an integer vector of length one

The output of the function will be a numeric vector of length length which contains a sequence of values.

The first element of the vector will be first.
The vector will contain length elements.
The second element should be first * multi. The third element is the second element multiplied by multi. And so on.

There are many ways to accomplish this task (and try a few if you’re interested) but the intention of this exercise is for you to write a for loop. (Clever math would allow you to avoid it.)