How do you sort a dictionary by keys and values?

Python Data Structures - Interview Questions and Answers

Sorting a dictionary in Python can be done in two ways:

Sorting by Keys
Sorting by Values

Since dictionaries are unordered before Python 3.7, sorting creates a new dictionary with a specific order.

1. Sorting a Dictionary by Keys

Use the sorted() function on dict.keys() and reconstruct the dictionary.

Example :

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

# Sorting by keys (ascending order)
sorted_dict = dict(sorted(my_dict.items()))
print(sorted_dict)  # Output: {'a': 1, 'b': 2, 'c': 3}

* Default sorting is in ascending order (A → Z, 0 → 9).
* Use reverse=True for descending order.

2. Sorting a Dictionary by Values

Sort based on the second element in (key, value) pairs.

Example :

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

# Sorting by values (ascending order)
sorted_by_values = dict(sorted(my_dict.items(), key=lambda item: item[1]))
print(sorted_by_values)  # Output: {'a': 1, 'b': 2, 'c': 3}

* Sorting is based on values instead of keys.
* Use reverse=True for descending order.

3. Sorting by Keys in Descending Order

sorted_dict_desc = dict(sorted(my_dict.items(), reverse=True))
print(sorted_dict_desc)  # Output: {'c': 3, 'b': 2, 'a': 1}

4. Sorting by Values in Descending Order

sorted_by_values_desc = dict(sorted(my_dict.items(), key=lambda item: item[1], reverse=True))
print(sorted_by_values_desc)  # Output: {'c': 3, 'b': 2, 'a': 1}

Which Method Should You Use?

Sorting Criteria	Code
Sort by Keys (Ascending)	`dict(sorted(my_dict.items()))`
Sort by Keys (Descending)	`dict(sorted(my_dict.items(), reverse=True))`
Sort by Values (Ascending)	`dict(sorted(my_dict.items(), key=lambda item: item[1]))`
Sort by Values (Descending)	`dict(sorted(my_dict.items(), key=lambda item: item[1], reverse=True))`