Remove Empty Keys In Dictionary Python

In this Python tutorial, I will explain how to remove empty keys in dictionary Python. We will first define what is an empty key in a Python dictionary, and what are the different methods to remove empty keys from dictionary Python.

Dictionaries in Python are versatile and widely-used data structures that allow the storage of key-value pairs. In various applications, we might encounter dictionaries with empty keys or keys that have empty values. It’s often desirable to remove such entries to clean up the data.

A dictionary is a built-in data type in Python. It’s defined by enclosing key-value pairs within curly braces {}. For instance:

capital_cities = {
    "California": "Sacramento",
    "Texas": "Austin",
    "Florida": "Tallahassee"
}

Table of Contents

What “empty key or value” means in a Python dict

Before we dive into the process, it’s crucial to define what “empty key or empty value” means in this context:

An empty key: A key that’s an empty string "" or any other data type that’s considered “falsy” in the Python dictionary.
An empty value: Typically a value that’s either None, an empty string, list, set, or another dictionary.

For instance, let’s take some states of the USA and store their capital cities in a dictionary but, we don’t know some of them. so the Python dictionary will look like this:

capital_cities = {
    "California": "",
    "": "Austin",
    "Florida": None,
    "New York": [],
    "Alaska": {}
}

print(capital_cities.keys())
print(capital_cities.values())

Here, “California“, “Florida“, “New York“, "", and “Alaska” are considered empty keys or empty values in the Python dictionary.

Remove empty keys in dictionary Python methods

There are four different methods to remove keys with empty values in Python dict:

Using Dictionary Comprehension
Using the dict constructor with an iterator
Using a for loop
Using filter() function

Let’s see them one by one with demonstrative examples:

Method-1: Python remove empty keys from dict using dictionary comprehension

The Dictionary comprehension in Python offers a concise way to construct dictionaries by iterating over an existing one, and filtering out unwanted keys(empty keys or keys with empty values) in the process. It is Ideal for removing multiple keys from dict Python based on a condition.

The syntax of dictionary comprehension in Python is:

{k: v for k, v in original_dict.items() if condition}

For instance, Imagine we have a Python dictionary that links NFL teams to their home stadiums. However, due to incomplete data collection, some teams or stadiums might be missing or empty. To submit the report we need to remove empty keys from dictionary Python.

nfl_stadiums = {
    "San Francisco 49ers": "Levi's Stadium",
    "Dallas Cowboys": "",
    "Green Bay Packers": "Lambeau Field",
    "": "Mercedes-Benz Stadium",
    "Arizona Cardinals": None
}

nfl_stadiums = {team: stadium for team, stadium in nfl_stadiums.items() if team and stadium}
print(nfl_stadiums)

The output is:

{'San Francisco 49ers': "Levi's Stadium", 'Green Bay Packers': 'Lambeau Field'}

remove empty values from dictionary python with dictionary comprehension

Here, we have combinedly removed the empty key and key with empty values. But, we can do it separately too:

Removing Empty Keys:

nfl_stadiums = {team: stadium for team, stadium in nfl_stadiums.items() if team}

This will remove just the empty key "" in this example of Python.

Removing Keys with Empty Values:

nfl_stadiums = {team: stadium for team, stadium in nfl_stadiums.items() if stadium}

This will remove the keys with empty values “Dallas Cowboys” and “Arizona Cardinals” in this example of Python.

Method-2: Python dict remove keys with empty values using the dict constructor within an iterator

The dict constructor is another way to construct Python dictionaries. It can be combined with list comprehension to filter out empty keys/values.

For example, Perhaps we’re working with a Python dictionary that maps U.S. states to their abbreviations. Due to some data inconsistencies, some states or abbreviations are empty or missing. To clean the Python dict., we will remove keys with empty values.

state_abbreviations = {
    "California": "CA",
    "Texas": "",
    "Florida": "FL",
    "": "AZ",
    "Nevada": None
}

state_abbreviations = dict((state, abbrev) for state, abbrev in state_abbreviations.items() if state and abbrev)
print(state_abbreviations)

The output is:

{'California': 'CA', 'Florida': 'FL'}

python dictionary remove empty values using dict constructor

This way the dict constructor, cleans the Python dictionary with empty keys.

Method-3: Python dict remove empty values using a for loop

The For loop manually iterates and filters out keys with empty values in the Python dictionary:

For instance, Imagine a scenario where we have a Python dictionary linking American car brands to the cities they originated from. Due to various reasons, some data might be incomplete. Let’s remove these data from the Python dict.

car_brands_origin = {
    "Ford": "Dearborn",
    "Chevrolet": "",
    "Tesla": "Palo Alto",
    "": "Detroit",
    "Jeep": None
}

filtered_dict = {}
for brand, city in car_brands_origin.items():
    if brand and city:
        filtered_dict[brand] = city
print(filtered_dict)

The output is:

{'Ford': 'Dearborn', 'Tesla': 'Palo Alto'}

python remove empty values from dict using for loop

This way the for loop helps to remove dict Python empty keys.

Method-4: Remove empty keys from dictionary Python from the filter() function

The filter() function allows for processing each key-value pair in a Python dictionary to determine if it should be kept. It’s useful for quickly removing empty or unwanted entries based on a defined condition.

For instance, Imagine we’re building a Python dictionary of U.S. musicians and their most famous songs. Due to various data sources, we might end up with some empty entries.

Here, we will use the filter() function with the lambda function as a conditional statement in Python to filter out the desired keys and create a new Python dictionary using the dict constructor.

musicians_songs = {
    "Elvis Presley": "Jailhouse Rock",
    "Madonna": "",
    "Michael Jackson": "Billie Jean",
    "": "Born in the U.S.A.",
    "Whitney Houston": None
}

musicians_songs = dict(filter(lambda item: item[0] and item[1], musicians_songs.items()))
print(musicians_songs)

The output is:

{'Elvis Presley': 'Jailhouse Rock', 'Michael Jackson': 'Billie Jean'}

python dict remove none using filter() function

This way, in Python dict remove ‘none’ values or empty key.

Conclusion

Here, we have seen how to remove empty keys in dictionary Python with four different methods in Python like dictionary comprehension, dict constructor, for loop, and filter() function using demonstrative examples.

Cleaning Python dictionaries by removing empty keys or values is a straightforward process in Python. With the methods discussed, we can ensure our data remains tidy and meaningful.