How to Extract Keys and Values from a Python Dictionary as Lists

A Python Dictionary is a data structure composed of keys and values, and it's used in various data processing tasks. In this post, we will introduce various methods to extract keys and values from a Dictionary separately and convert them into lists.

1. Extracting Only Keys from a Dictionary

To extract keys from a Dictionary, use the keys() method. This method returns all keys of the Dictionary, and you can wrap it with list() to convert it into a list.

Example 1: Using the keys() Method

my_dict = {'name': 'Alice', 'age': 25, 'city': 'Seoul'}

# Extracting keys into a list
keys_list = list(my_dict.keys())
print(keys_list)  # Output: ['name', 'age', 'city']

Example 2: Using List Comprehension

You can also extract keys into a list using the keys() method along with a for loop.

keys_list = [key for key in my_dict]
print(keys_list)  # Output: ['name', 'age', 'city']

2. Extracting Only Values from a Dictionary

To extract values from a Dictionary, use the values() method. This method returns all values of the Dictionary, and you can similarly convert it using list().

Example 1: Using the values() Method

my_dict = {'name': 'Alice', 'age': 25, 'city': 'Seoul'}

# Extracting values into a list
values_list = list(my_dict.values())
print(values_list)  # Output: ['Alice', 25, 'Seoul']

Example 2: Using List Comprehension

You can also extract values from the Dictionary into a list using a for loop.

values_list = [value for value in my_dict.values()]
print(values_list)  # Output: ['Alice', 25, 'Seoul']

3. Extracting Keys and Values Simultaneously

If you want to extract keys and values into their respective lists at the same time, you can use the following methods.

Example: Using keys() and values() Together

my_dict = {'name': 'Alice', 'age': 25, 'city': 'Seoul'}

# Extracting keys and values into lists simultaneously
keys_list = list(my_dict.keys())
values_list = list(my_dict.values())

print(keys_list)   # Output: ['name', 'age', 'city']
print(values_list) # Output: ['Alice', 25, 'Seoul']

Example: Using items() and Unpacking

my_dict = {'name': 'Alice', 'age': 25, 'city': 'Seoul'}

keys_list = [key for key, _ in my_dict.items()]
values_list = [value for _, value in my_dict.items()]

print(keys_list)   # Output: ['name', 'age', 'city']
print(values_list) # Output: ['Alice', 25, 'Seoul']

4. Creating a List of Combined Keys and Values

If you want to store keys and values from a Dictionary as pairs in a list, you can use the items() method.

Example: Creating a List of Key-Value Pairs

my_dict = {'name': 'Alice', 'age': 25, 'city': 'Seoul'}

# Extracting key-value pairs into a list
pairs_list = list(my_dict.items())
print(pairs_list)  # Output: [('name', 'Alice'), ('age', 25), ('city', 'Seoul')]

5. Application: Creating a Sorted List of Keys or Values

If you want to create sorted lists of keys and values, you can use sorted().

Example 1: Sorting Keys into a List

my_dict = {'b': 2, 'a': 1, 'c': 3}

sorted_keys = sorted(my_dict.keys())
print(sorted_keys)  # Output: ['a', 'b', 'c']

Example 2: Sorting Values into a List

sorted_values = sorted(my_dict.values())
print(sorted_values)  # Output: [1, 2, 3]

6. Summary

Utilize the various methods to extract keys and values from a Python Dictionary into lists for more efficient data processing tasks! 😊