Sort Python Dictionary by Key or Value - Python

Given a dictionary in Python, the task is to sort it by key or value, either in ascending or descending order. For Example:

Input: {'apple': 5, 'banana': 2, 'cherry': 7}
Output: {'banana': 2, 'apple': 5, 'cherry': 7}
Explanation: The dictionary is sorted by values in ascending order, since 2 < 5 < 7, the order becomes {'banana': 2, 'apple': 5, 'cherry': 7}.

Let's explore different methods to sort dictionary by key or value in Python.

Sorting by Value

1. Using sorted() with lambda: This method sorts the dictionary efficiently by its values using the sorted() function and a lambda expression.

{'watermelon': 1, 'apple': 2, 'banana': 3}

Explanation:

• sorted(d.items(), key=lambda item: item[1]): sorts by values (ascending).
• Dictionary comprehension rebuilds the sorted dictionary.

2. Using OrderedDict: This method sorts a dictionary by values and stores the result in an OrderedDict, which preserves insertion order.

OrderedDict({'tuesday': 9, 'monday': 10, 'wednesday': 15})

Explanation:

• sorted(d.items(), key=lambda item: item[1]): sorts using the value of each key-value pair.
• OrderedDict(): stores the sorted order so it stays preserved.

3. Using for loop with sorted(): This method sorts and displays dictionary values in ascending order using for loop with sorted() function.

(1, 2) (2, 56) (3, 323) 

Explanation:

• sorted(d.items(), key=lambda item: item[1]): sorts dictionary by values.
• Loop prints key-value pairs in ascending order of their values.

4. Using NumPy: This approach uses NumPy’s argsort() for fast value-based sorting in numerical dictionaries.

{'diana': 2, 'ben': 9, 'alex': 10, 'clara': 15, 'eva': 32}

Explanation:

• np.argsort(v): returns indices that would sort the values.
• Dictionary comprehension rebuilds a new dictionary in value-sorted order.

Sorting by Key

1. Using sorted() with lambda: This method sorts the dictionary by its keys using sorted() and a lambda expression.

{'apple': 2, 'banana': 3, 'watermelon': 1}

Explanation:

• key=lambda item: item[0] → sorts using keys.
• Dictionary comprehension rebuilds the key-sorted dictionary.

2. Using OrderedDict: This method sorts dictionary items by key and stores them in an OrderedDict.

Explanation:

• sorted(d.items(), key=lambda item: item[0]): sorts by key.
• OrderedDict() preserves the sorted order.

3. Using for loop with sorted(): This method sorts and prints dictionary items using key-based sorting.

Explanation:

• sorted(d.items(), key=lambda item: item[0]): sorts by key.
• Loop prints key-value pairs in ascending key order.

4 Using NumPy: This method sorts the dictionary by converting keys to a NumPy array and using argsort() to get their sorted order.

{'alex': 10, 'ben': 9, 'clara': 15, 'diana': 2, 'eva': 32}

Explanation:

• np.argsort(k): returns indices that sort the keys alphabetically.
• Dictionary comprehension builds the key-sorted dictionary.

Related Articles:

• Sort a Dictionary
• Different ways of sorting Dictionary by Values and Reverse
• Different ways of sorting Dictionary by Keys and Reverse
• Ways to sort list of dictionaries by values
• Sort Dictionary key and values List