Penguin Body Condition (Functions)

Body condition describes the mass of an animal relative to the mass expected given its size. Individuals that are heavier than expected are considered to be in better condition.

If the file penguins.csv is not in your working directory then download it.

1. Write a function called est_mass_from_flipper that takes flipper_length (in mm), a, and b as arguments. Set default arguments for a = 0.018 and b = 2.33. The function should estimate the expected body mass using mass = a * flipper_length ^ b. Use the function to estimate the expected mass of a penguin with a flipper length of 200 mm.

2. Write a function called calc_body_condition that takes observed_mass and expected_mass as arguments and returns the body condition, where body condition is observed_mass / expected_mass. Use the function to calculate the body condition of a penguin that weighs 4200 g but was expected to weigh 4000 g.

3. Load penguins.csv using read_csv(). Use mutate() and the two functions you wrote to add a new column named body_condition to the data frame.

4. Calculate the average body_condition for each sex of each species.

5. Make an unstacked histogram of body condition with the bars colored by island with one subplot (facet) for each year.

Expected outputs for Penguin Body Condition