Iterators and iterables¶
Explore numbers object
numbers = [1,2,3,4]
print(dir(numbers))
value = iter(numbers)
item1 = value.__next__()
print(item1)
item2 = next(value)
print(item2)
Iterator objects¶
When running a for loop python builds an iterator behind the scenes as using a while loop as shown in the next code cell. Iterators are simply objects that implement the iter() method and the next() method.
num_list = [1,4,9]
iter_obj = iter(num_list) # builds an iterator object from an object
while(True):
try:
element = next(iter_obj)
print(element)
except StopIteration:
break
Generators¶
Generators allows to create iterators in an easier way. lets implement the code creating a custom iterator. Then less use the generator function to create the same iterator. (Generators are much simpler and they handle implcitly many things you do when implementing a custom iterator,not using the generator function)
Implementing a fibonacci generator¶
def generate_fibonacci(sequence_number):
result = []
count = 0
def generate_number():
n1 = 0
n2 = 1
while True:
result.append(n1)
n1, n2 = n2, n1 + n2
count += 1
while count <= sequence_number:
generate_number()
print(generate_fibonacci(5))