In this exercise, you will work with rivers data. The data pertain to the length of major North American rivers, and it is built-in data in R. You can access the data by typing:
> rivers
Your task is to build a function that returns descriptive statistics for different inputs. The function is named descriptive_function and has three arguments (i.e., another name of inputs).
descriptive_function(list, char, num)
The requirements of the function are as follows:
· The function has three arguments. The first argument is a list of numbers in doubles. The second argument is a character, and the last argument is a number.
· If char is ‘m ’, the function prints the arithmetic mean of the list.
· If char is ‘v’, the function prints the variance of the list.
· If char is ‘s’, the function prints the standard deviation of the list.
· If char is ‘z’, the function prints the z-score of num with respect to the list.
· You can use built-in R functions including mean(), var() and sd().
Sample test cases:
> descriptive_function(rivers, ‘m’, 7)
[1] 591.1844> descriptive_function(rivers, ‘m’)
[1] 591.1844> descriptive_function(rivers, ‘s’)
[1] 493.8708> descriptive_function(rivers, ‘v’, 8)
[1] 243908.4> descriptive_function(rivers, ‘z’, 8)
[1] -1.180844