How to Create a Data Dictionary in Python

In the world of programming, a data dictionary, also known as a hash map or associative array, is a very useful structure for storing data.

In Python specifically, the dictionary data type is essential due to its flexibility and efficient data access. This tutorial will guide you through creating and manipulating data dictionaries in Python.

What is a Python dictionary?

A Python dictionary is an unordered collection of data values. Unlike other data types that hold only a single value as an element, a dictionary holds key:value pairs.

The keys in a dictionary must be immutable (like numbers or strings) and unique. However, the dictionary values can be of any type and can be duplicated.

Creating a Dictionary

To create a dictionary in Python, you use curly brackets {} and separate the keys and values with a colon. If you want to add more items, you can use a comma as a separator.

1 2	# create a dictionary details = {'name':'John', 'age':25, 'country':'USA'}

You can also create a dictionary using the built-in dict() function.

1 2	# create a dictionary using dict() function details = dict(name='John', age=25, country='USA')

Accessing Items

To access dictionary elements, you can use the familiar square brackets along with the key to obtain its value. You can also use the get() method to access the value.

# access elements from the dictionary

print(details['name'])

print(details.get('age'))

Updating a Dictionary

Updating a dictionary means adding a new item or changing the value of an existing item. If the key already exists, then the existing value gets updated. In case the key is not present, a new key:value pair is added to the dictionary.

# update a dictionary

details['age'] = 26 # update existing value

details['profession'] = 'Doctor' # add new key:value pair

Before the conclusion, let’s quickly review the full code content.

Full Code

# create a dictionary

details = {'name':'John', 'age':25, 'country':'USA'}

# create a dictionary using dict() function

details = dict(name='John', age=25, country='USA')