0.python_iterators_generators.md

Code samples to demonstrate Python iterators and the use of yield statements to create a generator.

Examples based directly on the instruction from Programiz' YouTube Channel

• #28: Iterators in Python | Python for Beginners
• #29: Generators in Python: How to Use them & Why? | Python for Beginners

In the second video, the insturctor summarizes "yield" in the following way:

The difference between yield and return is that the return terminates the function completely while yield pauses the function, saving all it's states for next successive calls

1.iterator.py

class Even:
    def __init__(self, max):
        self.n = 2
        self.max = max
    def __iter__(self):
        return self
    def __next__(self):
        if self.n <= self.max:
            result = self.n
            self.n += 2
            return result
        else:
            raise StopIteration

numbers = Even(10)
print(next(numbers)) # 2
print(next(numbers)) # 4
print(next(numbers)) # 6
print(next(numbers)) # 8

2.yield_static.py

def even_generator_static_yield():
    n = 0
    n+=2
    yield n
    n+=2
    yield n
    n+=2
    yield n
    n+=2
    yield n

numbers = even_generator_static_yield()
print(next(numbers)) # 2
print(next(numbers)) # 4
print(next(numbers)) # 6
print(next(numbers)) # 8

3.yield_loop.py

def even_generator_dynamic_yield(max):
    n = 0
    while n <= max:
        yield n
        n += 2

numbers = even_generator_dynamic_yield(10)
print(next(numbers)) # 2
print(next(numbers)) # 4
print(next(numbers)) # 6
print(next(numbers)) # 8