Python built-in Method - iter()

In Python, the iter() method is a built-in function that returns an iterator object for a given iterable. An iterator is an object that allows you to traverse through all the elements of an iterable, one at a time, without having to store the entire iterable in memory.

The syntax for iter() is as follows:

iter(iterable, sentinel)

Here, iterable is the iterable object for which the iterator is to be created, and sentinel is an optional parameter that can be used to specify a stopping condition for the iterator. If sentinel is not provided, the iterator will continue indefinitely.

For example:

my_list = [1, 2, 3, 4, 5]
my_iterator = iter(my_list)

print(next(my_iterator))    # 1
print(next(my_iterator))    # 2
print(next(my_iterator))    # 3

In the example above, we create a list my_list and an iterator my_iterator using the iter() function. We then use the next() method to iterate through the first three elements of my_list.

The iter() function is useful when you need to process large amounts of data that cannot be stored in memory all at once. It allows you to process the data in small chunks, one at a time, and can be used in conjunction with the for loop to simplify the processing code.

Note that the iter() function can be called on any iterable object in Python, including lists, tuples, dictionaries, strings, and custom objects that implement the __iter__() method. If the iter() function is called on an object that is already an iterator, the same iterator object will be returned.