Making choices size estimates by name.qmd (solution)

Exercise

You’re going to write a function to estimate a dinosaur’s mass based on its length. The general form of the equation for doing this is:

mass <- a * length ^ b

The parameters a and b vary by the group of dinosaurs, so you decide to create a function that lets you specify which dinosaur group you need to estimate the size of by name and then have the function automatically choose the right parameters.

Create a new function get_mass_from_length_by_name() that takes two arguments, the length and the name of the dinosaur group. Inside this function use if/else if/else statements to check to see if the name is one of the following values and if so use the associated a and b values to estimate the species mass using these equations:

If the name is not any of these values the function should return NA.

Run the function for: 1. A Stegosauria that is 10 meters long. 2. A Theropoda that is 8 meters long. 3. A Sauropoda that is 12 meters long. 4. A Ankylosauria that is 13 meters long.

Challenge (optional): If the name is not one of values that have a and b values print warning that it doesn’t know how to convert that group that includes that groups name in a message like “No known estimation for Ankylosauria”. You can use the function warning("your warning text") to print a warning and the function paste() to combine text with a value from a variable paste("My name is", name). Doing this successfully will modify your answer to (4), which is fine.

Challenge (optional): Change your function so that it uses two different values of a and b for Stegosauria. When Stegosauria is greater than 8 meters long use the equation above. When it is less than 8 meters long use a = 8.5 and b = 2.8. Run the function for a Stegosauria that is 6 meters long.

Output solution 
[1] 4779.848
[1] 1385.286
[1] 8070.685
Warning in get_mass_from_length_by_name(13, "Ankylosauria"): No known
estimation for Ankylosauria
[1] NA

Challenge 1 Adds a warning to the 4th answer above

Challenge 2

[1] 1283.047