How to Sort a Dictionary in Python

In Python, dictionaries are unordered collections of items. However, you can sort a dictionary by its keys or values and create a new sorted dictionary or a list of tuples. Below are some common methods to sort a dictionary in Python.

1. Sorting a Dictionary by Keys

To sort a dictionary by its keys, you can use the sorted() function, which returns a list of sorted keys. You can then use a dictionary comprehension or convert the sorted list back to a dictionary.

Example:

# Sorting a dictionary by keys
my_dict = {'b': 3, 'a': 2, 'c': 1}
sorted_dict = {k: my_dict[k] for k in sorted(my_dict)}
print(sorted_dict)

Output:

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

In this example, the dictionary is sorted by its keys in ascending order.

2. Sorting a Dictionary by Values

To sort a dictionary by its values, you can use the sorted() function with a lambda function to specify that the sorting should be done based on the dictionary’s values.

Example:

# Sorting a dictionary by values
my_dict = {'b': 3, 'a': 2, 'c': 1}
sorted_dict = {k: v for k, v in sorted(my_dict.items(), key=lambda item: item[1])}
print(sorted_dict)

Output:

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

In this example, the dictionary is sorted by its values in ascending order.

3. Sorting a Dictionary by Keys in Descending Order

You can sort the dictionary by keys in descending order by setting the reverse parameter of the sorted() function to True.

Example:

# Sorting a dictionary by keys in descending order
my_dict = {'b': 3, 'a': 2, 'c': 1}
sorted_dict = {k: my_dict[k] for k in sorted(my_dict, reverse=True)}
print(sorted_dict)

Output:

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

In this example, the dictionary is sorted by its keys in descending order.

4. Sorting a Dictionary by Values in Descending Order

Similarly, you can sort the dictionary by its values in descending order by setting the reverse parameter to True.

Example:

# Sorting a dictionary by values in descending order
my_dict = {'b': 3, 'a': 2, 'c': 1}
sorted_dict = {k: v for k, v in sorted(my_dict.items(), key=lambda item: item[1], reverse=True)}
print(sorted_dict)

Output:

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

In this example, the dictionary is sorted by its values in descending order.

5. Sorting a Dictionary by Keys and Values Using OrderedDict

The collections.OrderedDict can be used to maintain the order of the sorted dictionary.

Example:

from collections import OrderedDict

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

Output:

OrderedDict([('a', 2), ('b', 3), ('c', 1)])

In this example, OrderedDict maintains the order of the sorted items.