Size Estimates by Name (Making Choices)
This is a follow up to Use and Modify.
To make it even easier to work with your dinosaur size estimation functions 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.
- Stegosauria:
a=10.95andb=2.64(Seebacher 2001). - Theropoda:
a=0.73andb=3.63(Seebacher 2001). - Sauropoda:
a=214.44andb=1.46(Seebacher 2001).
If the name is not any of these values the function should return NA.
Run the function for:
- A Stegosauria that is 10 meters long.
- A Theropoda that is 8 meters long.
- A Sauropoda that is 12 meters long.
- A Ankylosauria that is 13 meters long.
Challenge (optional): If the name is not one of values that have a and
b values print out a message that it doesn’t know how to convert that group that includes that groups name in a message like “No known estimation for Ankylosauria”. (the function paste() will be helpful here). 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.
Challenge (optional): Rewrite your function so that instead of calculating mass directly it sets the values of a and b to the values for the species (or to NA if the species doesn’t have an equation) and then calls another function to do the basic mass = a * length ^ b calculation.