How to Sort a Dictionary in Python

How to Sort a Dictionary in Python

A robust data structure for storing key-value pairs is a Python dictionary. They are mutable, meaning their contents can be modified after creation. However, dictionaries are inherently unordered, which means the data is not stored in a specific sequence.

While a dictionary permits duplicate values, each key must be distinct. Dictionaries are declared using curly braces {}, with key-value pairs separated by commas.

Complete Python Course with Advance topics:-Click here

Example:

student_info = {'name': 'Devansh', 'age': 22, 'Rollno': 90014}
print(student_info)

Output:

{'name': 'Devansh', 'age': 22, 'Rollno': 90014}

Why Is Sorting a Dictionary Necessary?

Sorting dictionaries can be helpful in various scenarios:

• The search time complexity of a list is O(n), while dictionaries offer O(1) lookup time, making them faster for key-based searches.
• Sorting helps in analyzing data efficiently when working with data structures.
• A sorted dictionary improves readability and simplifies complex operations.

Methods to Sort a Dictionary:

1. Sorting by Keys
2. Sorting by Values
3. Using Custom Sorting Algorithms
4. Reversing the Sorted Order

1. Sorting a Dictionary by Keys

Python provides built-in functions like keys() and items() to sort a dictionary based on its keys.

Example:

names = {1: 'Alice', 2: 'John', 4: 'Peter', 3: 'Andrew', 6: 'Ruffalo', 5: 'Chris'}  
# Print sorted keys
print(sorted(names.keys()))  
# Print sorted dictionary items
print(sorted(names.items()))

Output:

[1, 2, 3, 4, 5, 6]
[(1, 'Alice'), (2, 'John'), (3, 'Andrew'), (4, 'Peter'), (5, 'Chris'), (6, 'Ruffalo')]

Explanation:

• The dictionary keys are arranged in ascending order using the sorted() function.
• The sorted dictionary can be obtained as key-value tuples by using items().

2. Sorting a Dictionary by Values

To sort the dictionary according to values, we can combine a lambda function with the sorted() method.

Example:

dict_scores = {'Alice': 85, 'John': 92, 'Peter': 78, 'Andrew': 90}  
# Sort by values
sorted_scores = dict(sorted(dict_scores.items(), key=lambda x: x[1]))  
print(sorted_scores)

Output:

{'Peter': 78, 'Alice': 85, 'Andrew': 90, 'John': 92}

Explanation:

• The sorted() function sorts based on the second element (value) of each key-value pair using lambda x: x[1].
• The outcome is then transformed back into a dictionary.

3. Sorting a Dictionary Using Custom Algorithms

For more individualized sorting, Python lets us utilize additional arguments in the sorted() function.

Example:

daynames = {'one': 'Monday', 'six': 'Saturday', 'three': 'Wednesday', 'two': 'Tuesday', 'five': 'Friday', 'seven': 'Sunday'}  
print(daynames)  
number = {'one': 1, 'two': 2, 'three': 3, 'four': 4, 'five': 5, 'six': 6, 'seven': 7}  
print(sorted(daynames, key=number.__getitem__))  
print([daynames[i] for i in sorted(daynames, key=number.__getitem__)])

Output:

{'one': 'Monday', 'six': 'Saturday', 'three': 'Wednesday', 'two': 'Tuesday', 'five': 'Friday', 'seven': 'Sunday'}
['one', 'two', 'three', 'five', 'six', 'seven']
['Monday', 'Tuesday', 'Wednesday', 'Friday', 'Saturday', 'Sunday']

Explanation:

• The dictionary is sorted based on a predefined numbering of days.
• We use number.__getitem__ to define the sorting order.

4. Reversing the Sorted Order

By using the reverse=True argument, we can sort dictionaries in descending order.

Example:

a = {'a': 2, 'b': 1, 'c': 3, 'd': 4, 'e': 5, 'f': 6}  
print(sorted(a.values(), reverse=True))

Output:

[6, 5, 4, 3, 2, 1]

Explanation:

• reverse=True ensures that the sorted values appear in descending order.

Download New Real Time Projects :-Click here
Complete Advance AI topics:- CLICK HERE

Conclusion

Sorting a dictionary in Python is an essential skill when dealing with large datasets. Whether you sort by keys, values, or use custom sorting logic, Python’s built-in functions make it easy to manipulate dictionaries efficiently. By mastering dictionary sorting, you can improve the performance and readability of your Python applications.

For more Python tutorials, stay tuned to UpdateGadh!

sort dictionary by value python
how to sort a dictionary by key in python
how to sort a dictionary in python without sort function
sort dictionary by value python descending
python sort dictionary by key=lambda
how to sort a dictionary in python alphabetically
how to sort a dictionary in python
how to sort a dictionary in python by value
how to sort a dictionary in python by value descending
how to sort a dictionary in python based on values
how to sort a dictionary in python by keys
how to sort a dictionary in alphabetical order python
lambda function in python
sorted python