Recently, in a Python webinar, someone asked me a question about covering a dictionary to list. After researching and testing, I found a few effective ways to accomplish this task. In this tutorial, I will explain how to convert a dictionary to a list in Python with suitable examples and screenshots.
Dictionaries in Python
Before getting into the conversion process, it’s important to understand what a dictionary is in Python. A dictionary is an unordered collection of items that store data in key-value pairs. For instance, consider the following dictionary that holds information about some popular American cities:
cities = {
'New York': 'NY',
'Los Angeles': 'CA',
'Chicago': 'IL',
'Houston': 'TX',
'Phoenix': 'AZ'
}In this example, the city names serve as keys, while their corresponding state abbreviations are the values.
Read How to Randomly Select from a List in Python?
Convert a Dictionary to a List in Python
There are several ways to convert a dictionary to a list in Python. Below, I will outline the most common methods, complete with examples.
1. Convert Keys to a List
If you only need the keys from a Python dictionary, you can easily convert them to a list using the keys() method. Here’s how:
city_keys = list(cities.keys())
print(city_keys)Output:
['New York', 'Los Angeles', 'Chicago', 'Houston', 'Phoenix']You can see the output in the screenshot below.
Check out How to Get the Index of an Element in a List in Python?
2. Convert Values to a List
In some cases, you may want to extract just the values. You can achieve this using the Python values() following method:
city_values = list(cities.values())
print(city_values)Output:
['NY', 'CA', 'IL', 'TX', 'AZ']You can see the output in the screenshot below.
Read How to Merge Lists Without Duplicates in Python?
3. Convert Key-Value Pairs to a List of Tuples
If you want to retain both keys and values, you can convert the dictionary into a list of tuples using the items() method in Python. This method is particularly useful when you need to process both the keys and values together.
city_items = list(cities.items())
print(city_items)Output:
[('New York', 'NY'), ('Los Angeles', 'CA'), ('Chicago', 'IL'), ('Houston', 'TX'), ('Phoenix', 'AZ')]You can see the output in the screenshot below.
Check out How to Convert String to List in Python?
4. Use List Comprehensions
Python list comprehensions provide a concise way to create lists. You can use them to convert dictionary items into a list format that suits your needs. Here are some examples:
Example: List of City Names
city_list = [city for city in cities]
print(city_list)Output:
['New York', 'Los Angeles', 'Chicago', 'Houston', 'Phoenix']Example: List of State Abbreviations
state_list = [state for state in cities.values()]
print(state_list)Output:
['NY', 'CA', 'IL', 'TX', 'AZ']Read Convert String to List in Python Without Using Split
5. Create a List of Custom Objects
Sometimes, you might want to convert a dictionary to a list in Python of custom objects. For instance, if you have a dictionary of cities with their populations, you can create a list of city objects.
class City:
def __init__(self, name, state, population):
self.name = name
self.state = state
self.population = population
cities_with_population = {
'New York': {'state': 'NY', 'population': 8419600},
'Los Angeles': {'state': 'CA', 'population': 3980400},
'Chicago': {'state': 'IL', 'population': 2716000},
}
city_objects = [
City(name, info['state'], info['population'])
for name, info in cities_with_population.items()
]
for city in city_objects:
print(f"{city.name}, {city.state}: {city.population}")Output:
New York, NY: 8419600
Los Angeles, CA: 3980400
Chicago, IL: 2716000Check out How to Iterate Through a List in Python?
Handle Nested Dictionaries
When dealing with nested dictionaries, the conversion process may require a bit more complexity. For example, consider a dictionary that contains information about various cities, including their neighborhoods:
city_data = {
'New York': {
'state': 'NY',
'neighborhoods': ['Manhattan', 'Brooklyn', 'Queens']
},
'Los Angeles': {
'state': 'CA',
'neighborhoods': ['Hollywood', 'Beverly Hills', 'Santa Monica']
}
}To convert this nested dictionary into a list of neighborhoods, you can use a nested list comprehension:
neighborhoods = [
neighborhood
for city in city_data.values()
for neighborhood in city['neighborhoods']
]
print(neighborhoods)Output:
['Manhattan', 'Brooklyn', 'Queens', 'Hollywood', 'Beverly Hills', 'Santa Monica']Check out How to Write a List to a File in Python?
Conclusion
In this article, I explained how to convert a dictionary to a list in Python. I discussed converting keys to a list , converting values to a list , converting key-value pairs to a list of tuples, using list comprehension, and creating a list of custom objects. I also covered how to handle nested dictionaries.
You may read:
- How to Select Items from a List in Python?
- How to Add Tuples to Lists in Python?
- How to Convert Dictionary to List of Tuples in Python?
Bijay Kumar is an experienced Python and AI professional who enjoys helping developers learn modern technologies through practical tutorials and examples. His expertise includes Python development, Machine Learning, Artificial Intelligence, automation, and data analysis using libraries like Pandas, NumPy, TensorFlow, Matplotlib, SciPy, and Scikit-Learn. At PythonGuides.com, he shares in-depth guides designed for both beginners and experienced developers. More about us.
