Functions and Arguments Answer Key

Exercise 1

1. Let’s use base R function to calculate mean value of the glengths vector. You might need to search online to find what function can perform this task.

# Obtain the mean of glengths
mean(glengths)

[1] 10624.92

2. Create a new vector test <- c(1, NA, 2, 3, NA, 4). Use the same base R function from exercise 1 (with addition of proper argument), and calculate mean value of the test vector. The output should be 2.5.

# Create the test vector
test <- c(1, NA, 2, 3, NA, 4)
# Take the mean of the test vector while excluding NA values
mean(test, na.rm = TRUE)

[1] 2.5

3. Another commonly used base function is sort(). Use this function to sort the glengths vector in descending order.

# Sort the glengths vector in descending order
sort(glengths, decreasing = TRUE)

[1] 50000.0  3000.0    90.0    30.0     4.6

Exercise 2

Write a function called multiply_it, which takes two inputs: a numeric value x, and a numeric value y. The function will return the product of these two numeric values, which is x * y. For example, multiply_it(x=4, y=6) will return output 24.

# Create the multiply_it function that accepts values of x and y
multiply_it <- function(x,y) {
  # Multiply x and y and assign the product to the object called product
  product <- x * y
  # Return the product object to the console
  return(product)
}

# Using the multiply_it function, multiply x and y using 4 and 6, respectively
multiply_it(x = 4, y = 6)

[1] 24