Description
>>> f r o m m a t h i m p o r t factorial
>>> factorial( 5)
>>> 120
As shown above, we can use the factorial function from the math module. Here, you’ll write your own factorial function. First, we start with a simple function that returns the pro duct of its two inpu ts:
def mult(x, y):
“””Returns the product of x and y””” return x * y
Nothing too surprising here. Now, take a look at this:
>>> reduce(mult, [2, 3])
6
>>> reduce(mult, [2, 3, 4])
24
>>> reduce(mult, [1, 2, 3, 4])
24
Notice that reduce takes two inputs: A function and a list and it applies that function to “compress” the list into a single value. In this case, it multiplied all of the values together.
Now, write a function factorial(n) that takes a positive integer n and returns n!.
This is “mean”…
>>> len([1, 3, 5])
3
>>> len(range(1,10))
9
Here is the mean function in action:
>>> mean([1, 2, 3])
2
>>> mean([1, 1, 1])
1
