Description
Writing your own factorial function
>>> from math import 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 product of its two inputs:
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”…
|
Finally, write a function called mean(L) that takes a list as input and returns the mean (average) |
|
value in that list. Using reduce will be handy here. You may also want to define an add function that |
CS115 – Hw 1
|
returns the sum of two numbers. You’ll need to know the number of elements in the list. This can be |
|
found using the built-in function len. For example: >>> len([1, 3, 5]) 9 |
Here is the mean function in action:
>>> mean([1, 2, 3]) 2 >>> mean([1, 1, 1]) 1
CS115 – Hw 1
