functional.py

# Map, filter, and reduce are all operations that we can apply against a list, tuple, or sequence
# These types of operations follow the "functional" approach to programming
# I won't go into too much detail here, but a Google search of "functional vs OOP" will give you a synopsis

# Here are some examples. We can talk more about them when we chat.
# Let's start with a simple list...
>>> my_list = [0, 1, 2, 3, 4, 5]

# Using filter, we can filter values out of the list, returning a new list!
# (If you haven't seen lambdas yet, don't worry! Basically, this filter uses modulo 2 to check if the number is even/odd)
>>> filtered = filter(lambda x: x % 2, my_list)
>>> [x for x in filtered]
[1, 3, 5]

# Using map, we also get a new list. This time, runs a function for every value in the list to get a new "mapped" value
# The lambda here multiplies each value in the list times two
>>> mapped = map(lambda x: x * 2, my_list)
>>> [x for x in mapped]
[0, 2, 4, 6, 8, 10]

# Using reduce, we can "reduce" an entire list down to a single value
# Here, the lambda just does a simple sum for every value in the list
>>> from functools import reduce
>>> reduced = reduce(lambda a, b: a+b, my_list)
>>> reduced
15