Iterables
Iterators
An iterator is an object that allows you to traverse through a sequence of data one element at a time. It doesn’t load the entire sequence into memory at once, making it memory-efficient for large datasets.
Key characteristics:
__iter__method: Returns the iterator object itself.__next__method: Returns the next item in the sequence. RaisesStopIterationwhen there are no more items.
Creating an Iterator:
class MyIterator:
def __init__(self, data):
self.data = data
self.index = 0
def __iter__(self):
return self
def __next__(self):
if self.index >= len(self.data):
raise StopIteration
value = self.data[self.index]]
self.index += 1
return value
my_iterator = MyIterator(1, 2, 3, 4, 5)
for item in my_iterator:
print(item)
#Manual Iteration
my_iterator = MyIterator(1,2,3)
print(next(my_iterator))
print(next(my_iterator))
print(next(my_iterator))
#print(next(my_iterator)) #StopIteration
Iterating over different data structures:
Python’s built-in functions and data structures already support iteration. You don’t always need to create custom iterators.
Example with for loop (implicitly using iterators):
my_list = [10, 20, 30]]
for item in my_list: #The for loop implicitly calls iter() and next()
print(item)