How to use Python iter() function

By Ashwani Jaiswal

In this article, we will learn how iterator works and how you can build your own iterator using iter() function in Python.

Introduction of Python Iterators

iter() function is used for creating objects which can be iterated every time.

iter() uses next() for accessing values.Iterator also makes our code look cool.

Examples of using iter() function in Python

Here are some of the examples of iter() function. We will implement this function on the list and tuple.

Use iter() on list

l=[1,2,3,4,5]
# convert this list to iterable iterator
l=iter(l)
# Now using next(iterator) we can iterate every element in given list
print(next(l))
print(next(l))
print(next(l))
print(next(l))
print(next(l))

Output

1
2
3
4
5

Using iter() on tuple

# Creating a tuple having values in string
web=("code","speedy","provides","good","articles")
values=iter(web)
# Now values uses iterable iterator on given list named web
# Now using next() we can iterate every token of given list
for in range(5):
   print(next(values)) 
# printing token of given list

Output

code
speedy
provides
good
articles

Let’s Implement a program using iterators. The iterator you can see below will return all the odd numbers.

class InfiniteOddIterator:
    #Infinite iterator to return all odd numbers

    def __iter__(self):
        self.num = 1
        return self

    def __next__(self):
        num = self.num
        self.num += 2
        return num

We have created the class now let’s make its object and calling it.

object = iter(InfiniteOddIterator())

>>> next(object) 
next(object) 
1
>>> next(object) 
next(object) 
3
>>> next(object) 
next(object) 
5
>>> next(object) 
next(object) 
7
>>> next(object) 
next(object) 
9

Output

1
3
5
7
9

In this program, we could get all the odd numbers without storing the entire number system in memory. We can have infinite items in finite memory.

I hope you found this article helpful How to use iter() in Python.

Also read:

• What are the differences between Python dict.items() and dict.iteritems() method