Calculate the average of the petal lengths (Petal.Length) of each flower species (Species), and store the results in the vector a. The average values should be in the order setosa, versicolor, virginica. Hint: for example, you can use the aggregate function.
(b) Among individuals with a sepal width (Sepal.Width) less than 3.2, find the maximum sepal length (Sepal.Length) for each flower species. Store the largest lengths in vector b in the order setosa, versicolor, virginica.