python sort dictionary alphabetically by key with code examples

Python offers several ways to sort a dictionary based on its keys. Sorting the keys in alphabetical order can be done using the built-in sorted function or by converting the dictionary to a list of tuples, sorting the list, and then constructing a new dictionary from the sorted list.

In this article, we will explore both methods in detail, including code examples for each method.

Method 1: Using the built-in sorted function

The simplest way to sort a dictionary in alphabetical order by its keys is to use the built-in sorted function. The sorted function takes an iterable object as its input and returns a sorted list of elements.

Here is an example of how to sort a dictionary in alphabetical order by its keys using the sorted function:

d = {'dog': 10, 'cat': 5, 'bird': 20}

sorted_keys = sorted(d.keys())

sorted_dict = {}
for key in sorted_keys:
    sorted_dict[key] = d[key]

print(sorted_dict)

Output:

{'bird': 20, 'cat': 5, 'dog': 10}

In this example, we first sorted the keys of the dictionary using the sorted function and stored the result in a list named sorted_keys. Then, we created a new dictionary sorted_dict and populated it with the key-value pairs from the original dictionary d, using the sorted keys as the keys in the new dictionary.

Method 2: Converting the dictionary to a list of tuples

Another way to sort a dictionary in alphabetical order by its keys is to convert the dictionary to a list of tuples, sort the list, and then construct a new dictionary from the sorted list.

Here is an example of how to sort a dictionary in alphabetical order by its keys using this method:

d = {'dog': 10, 'cat': 5, 'bird': 20}

sorted_list = sorted(d.items(), key=lambda x: x[0])

sorted_dict = dict(sorted_list)

print(sorted_dict)

Output:

{'bird': 20, 'cat': 5, 'dog': 10}

In this example, we used the items method to convert the dictionary d to a list of tuples. The items method returns a list of key-value pairs as tuples, where each tuple consists of a key and its corresponding value.

Next, we used the sorted function to sort the list of tuples based on the first element of each tuple (the key), using the key parameter. The key parameter is set to a lambda function that returns the first element of the tuple.

Finally, we used the dict constructor to create a new dictionary sorted_dict from the sorted list of tuples.

Conclusion

In this article, we explored two methods for sorting a dictionary in alphabetical order by its keys in Python. The first method used the built-in sorted function to sort the keys and then construct a new dictionary from the sorted keys. The second method converted the dictionary to a list of tuples, sorted the list, and then constructed a new dictionary from the sorted list.

Both
In addition to sorting a dictionary by its keys, it is also possible to sort a dictionary by its values. This can be done using similar methods as described above, but with a few modifications.

Method 1: Using the built-in sorted function with items method

To sort a dictionary by its values, you can use the built-in sorted function in combination with the items method. The items method returns a list of key-value pairs as tuples, which can be sorted based on the values.

Here is an example of how to sort a dictionary in ascending order by its values using the sorted function with the items method:

d = {'dog': 10, 'cat': 5, 'bird': 20}

sorted_list = sorted(d.items(), key=lambda x: x[1])

sorted_dict = dict(sorted_list)

print(sorted_dict)

Output:

{'cat': 5, 'dog': 10, 'bird': 20}

In this example, the items method returns a list of tuples, where each tuple consists of a key and its corresponding value. The sorted function sorts this list of tuples based on the second element of each tuple (the value), using the key parameter. The key parameter is set to a lambda function that returns the second element of the tuple.

Finally, we used the dict constructor to create a new dictionary sorted_dict from the sorted list of tuples.

To sort the dictionary in descending order by its values, you can use the reverse parameter of the sorted function, as shown in the following example:

d = {'dog': 10, 'cat': 5, 'bird': 20}

sorted_list = sorted(d.items(), key=lambda x: x[1], reverse=True)

sorted_dict = dict(sorted_list)

print(sorted_dict)

Output:

{'bird': 20, 'dog': 10, 'cat': 5}

Method 2: Using the sorted method with a key function

It is also possible to sort a dictionary by its values using the sorted method directly on the dictionary, with a key function that returns the value for each key-value pair.

Here is an example of how to sort a dictionary in ascending order by its values using the sorted method with a key function:

d = {'dog': 10, 'cat': 5, 'bird': 20}

sorted_dict = dict(sorted(d.items(), key=lambda x: x[1]))

print(sorted_dict)

Output:

{'cat': 5, 'dog': 10, 'bird': 20}

In this example, the sorted method is applied directly to the dictionary, and the key parameter is set to a lambda function that returns the second element of each tuple (the value). The result of the sorted method is a sorted list of tuples, which is then passed to the dict constructor to create a new dictionary sorted_dict.

To sort the dictionary in descending order

Popular questions

1. What is the most common way to sort a dictionary by its keys in Python?

The most common way to sort a dictionary by its keys in Python is to use the built-in sorted function in combination with the items method. The items method returns a list of key-value pairs as tuples, which can then be sorted based on the keys using the sorted function.

2. How can you sort a dictionary in descending order by its keys?

To sort a dictionary in descending order by its keys, you can use the reverse parameter of the sorted function and set it to True. This will sort the list of key-value pairs in reverse order, effectively sorting the dictionary in descending order by its keys.

3. What is the difference between using the sorted function with the items method and using the sorted method directly on the dictionary?

The difference between using the sorted function with the items method and using the sorted method directly on the dictionary is that the items method returns a list of key-value pairs as tuples, which can then be sorted using the sorted function, while the sorted method directly on the dictionary returns a sorted view of the dictionary, which is not a dictionary itself.

4. How can you sort a dictionary by its values instead of its keys?

To sort a dictionary by its values instead of its keys, you can use the same methods as described above, but with a few modifications. You can either use the sorted function with the items method and a key function that returns the value for each key-value pair, or use the sorted method directly on the dictionary with a key function that returns the value for each key-value pair.

5. Can you provide a code example for sorting a dictionary in descending order by its values?

Yes, here is a code example for sorting a dictionary in descending order by its values:

d = {'dog': 10, 'cat': 5, 'bird': 20}

sorted_list = sorted(d.items(), key=lambda x: x[1], reverse=True)

sorted_dict = dict(sorted_list)

print(sorted_dict)

Output:

{'bird': 20, 'dog': 10, 'cat': 5}

In this example, the sorted function is used with the items method to sort the list of key-value pairs based on the values. The reverse parameter is set to True, which sorts the list in reverse order, effectively sorting the dictionary in descending order by its values.

Tag

Dictionary-Sorting