Appending a Dictionary to a List in Python

Appending a dictionary allows us to expand a list by including a dictionary as a new element. For example, when building a collection of records or datasets, appending dictionaries to a list can help in managing data efficiently. Let's explore different ways in which we can append a dictionary to a list in Python.

Using append()

append() method is the most straightforward and simple way to append a dictionary to a list.

a = [{'name': 'kate', 'age': 25}]
b = {'name': 'Nikki', 'age': 30}

# Append the dictionary to the list
a.append(b)

print(a)

[{'name': 'kate', 'age': 25}, {'name': 'Nikki', 'age': 30}]

Explanation:

• The append method directly adds the dictionary to the end of the list.
• This is the most efficient and straightforward way to achieve the task.

Let's explore some other methods and see how we can append a dictionary to a list.

Using += Operator

+=Operator combines the list with a single dictionary by creating a list containing the dictionary. We can extend the list with a single dictionary wrapped in a list.

a = [{'name': 'Kate', 'age': 25}]
b = {'name': 'Nikki', 'age': 30}

# Append the dictionary using += operator
a += [b]

print(a)

[{'name': 'Kate', 'age': 25}, {'name': 'Nikki', 'age': 30}]

Explanation:

• += operator modifies the original list in-place by concatenating it with another list.
• Wrapping the dictionary in a list ensures compatibility with the += operation.

Using extend()

extend() method expects an iterable so we must wrap the dictionary inside a list. While typically this is used to add multiple elements it works with a single dictionary as well.

a = [{'name': 'Kate', 'age': 25}]
b = {'name': 'Nikki', 'age': 30}

# Extend the list with a single dictionary
a.extend([b])

print(a)

[{'name': 'Kate', 'age': 25}, {'name': 'Nikki', 'age': 30}]

Explanation:

• The dictionary is wrapped in a list and added to the existing list using extend.
• This method is less efficient than append for single dictionaries.

Creating a New List with Concatenation

This method creates a new list by combining the existing list and the dictionary. + operator creates a new list without modifying the original list. This is useful when we want to retain the original list intact.

a = [{'name': 'Kate', 'age': 25}]
b = {'name': 'Nikki', 'age': 30}

# Create a new list by concatenating
c = a + [b]

print(c)

[{'name': 'Kate', 'age': 25}, {'name': 'Nikki', 'age': 30}]

Explanation:

• The dictionary is wrapped in a list and concatenated with the existing list.
• Although this method works, it is less efficient due to the creation of a new list.