fib_list.py

################################################################################
#
# Program: Generate A List Containing The Fibonacci Sequence
# 
# Description: Generate a list containing the Fibonacci Sequence numbers in 
# Python.
#
# YouTube Lesson: https://www.youtube.com/watch?v=Dvk7qqcU7QI 
#
# Author: Kevin Browne @ https://portfoliocourses.com
#
################################################################################

# The Fibonacci sequence is as follows:
# 
# 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...
#
# The first two numbers in the sequence are 0 and 1, with each additional 
# number in the sequence defined as the sum of the previous two.
#
# F0 = 0
# F1 = 1
# Fn = Fn-1 + Fn-2
#
# See: https://en.wikipedia.org/wiki/Fibonacci_sequence

# Returns a list containing the first n numbers of the Fibonacci sequence
def create_fib_sequence(n):

    # n <= 0 does not make sense, we can return None for this (or [])
    if n <= 0:
        return None
    # Return a list containing the first number of the Fibonacci sequence
    elif n == 1:
        return [0]
    else:
        # Begin with a list of the 2 Fibonacci sequence numbers
        fibs = [0,1]

        # This loop will execute n-2 times, and each time we append the next 
        # number in the Fibonacci sequence by summing the LAST two Fibonacci 
        # sequence numbers in the list.
        for i in range(2,n): 
            fibs.append( fibs[-1] + fibs[-2] )

        # Return the generated list
        return fibs

# Output the list containing the first 10 Fibonacci numbers
print( create_fib_sequence(10) )