Home » Python » Python Iterate over dictionaries Example

About Idris Azeez

Idris Azeez
Idris Azeez, is currently running a Masters program at the Nile University Of Nigeria, Abuja. He is a Java Developer with more than of 3 years programming experience. He has a strong passion for solving challenging tasks in the areas of health and education.

Python Iterate over dictionaries Example

1. Introduction

In programming, to iterate means to go over the items in an element. And when you iterate, you visit the various items in the element performing a specified action. Consider you have a bag of balls and you want to iterate over the balls, you visit each ball in the bag and perform a specified action. That is basically what iterating means.

And to iterate over a dictionary means to go over the items in a dictionary. But before proceeding any further, what exactly is a dictionary in Python? A dictionary is an unordered key-value store. The keys in a dictionary are unique while the values can be unique or not. With dictionaries, you can choose to loop over the keys, the values or both the keys and values at the same time.

When you iterate over a dictionary by key, it means that you go through the keys in the dictionary one after the other, and when you iterate over the values in a dictionary, you go from one value to another. Same with iterating over key-value pair.

So let us begin by looking at the various ways to iterate over a dictionary.

2. Iterate Over Keys

To iterate over a dictionary by keys, let us consider the following example.

student_details  = {'Name': 'AbdulBasit Kabir', 'Age': 32, 'Location': 'Abuja, Nigeria'}

If you directly run a for loop through the dictionary, you would be iterating over the keys in the dictionary. For example, consider the following:

for details in student_details:
    print(details)

And the output would be the following:

Name
Age
Location

You would get the same output if you run the for loop explicitly over the keys of the dictionary. To get the keys of the dictionary, you simply use keys() method. Consider the following example:

for details in student_details.keys():
    print(details)

And the output would be the following:

Name
Age
Location

You can also be interested in iterating over the keys in sorted order. That way, all you need is to call the sorted method in Python to sort the keys before you begin iteration. Consider when we sort the keys in student_details before iterating as follows:

for details in sorted(student_details.keys()):
    print(details)

The output in this case would have the keys sorted alphabetically

Age
Location
Name

3. Iterate Over Values

Remember when we said dictionaries are made of unordered keys and values. We have learned how to iterate over keys. Now the next question to ask is whether we can iterate over values. And the answer is YES.

To iterate over values in a dictionary, using a for loop, we do the following:

for values in student_details.values():
    print(values)

And the output is the following:

AbdulBasit Kabir
32
Abuja, Nigeria

If you would like to have the values sorted, you can call the sorted method right before you start printing. However, since our values are not all strings, we need to pass in a parameter to the method sorted as follows:

for values in sorted(student_details.values(), key=str):
    print(values)

And the output would be as follows:

32
AbdulBasit Kabir
Abuja, Nigeria

4. Iterate Over Keys and Values

Sometimes, you need to iterate not only on the keys or values but on both at the same time. Even in this situation, Python got you covered. The method items()is invoked on the dictionary so that it returns both the key and value during each iteration and with that, you can iterate over it as follows:

for items in student_details.items():
    print(items)

And the output would be as follows:

('Name', 'AbdulBasit Kabir')
('Age', 32)
('Location', 'Abuja, Nigeria')

To return both keys and values separately in each iteration, we can follow this pattern:

for key, value in student_details.items():
    print('Key: ', key)
    print('Value: ', value)

And the output would be:

Key:  Name
Value:  AbdulBasit Kabir
Key:  Age
Value:  32
Key:  Location
Value:  Abuja, Nigeria

And if you wish to print the key-value pair but sorted by key, then you can try the following:

for key, value in sorted(student_details.items()):
    print('Key: ', key)
    print('Value: ', value)

And the output would be as follows:

Key:  Age
Value:  32
Key:  Location
Value:  Abuja, Nigeria
Key:  Name
Value:  AbdulBasit Kabir

5. Python Iterate over dictionaries – Conclusion

In this example, we have learned what it means to iterate in programming and also how to iterate over dictionaries in Python. We learned a little on what dictionaries are and how we can iterate over them by key, value and both key or value.

6. Download the Source Code

This was an example of how to Iterate over dictionaries in Python

Download
You can download the full source code of this example here: Python Iterate over dictionaries Example
(0 rating, 0 votes)
You need to be a registered member to rate this.
Start the discussion Views Tweet it!
Do you want to know how to develop your skillset to become a Java Rockstar?
Subscribe to our newsletter to start Rocking right now!
To get you started we give you our best selling eBooks for FREE!
1. JPA Mini Book
2. JVM Troubleshooting Guide
3. JUnit Tutorial for Unit Testing
4. Java Annotations Tutorial
5. Java Interview Questions
6. Spring Interview Questions
7. Android UI Design
and many more ....
I agree to the Terms and Privacy Policy

Leave a Reply

avatar

This site uses Akismet to reduce spam. Learn how your comment data is processed.

  Subscribe  
Notify of