A Python dictionary is a data structure that allows for flexible storage and retrieval of key-value pairs. It is an unordered collection of data, meaning that items within the dictionary are not stored in any specific order.
In Python, dictionaries are denoted by curly braces { }, with each key-value pair separated by a colon (:). For example:
my_dict = {‘name’: ‘John’, ‘age’: 25, ‘occupation’: ‘developer’}
In this example, the keys are ‘name’, ‘age’, and ‘occupation’ and the corresponding values are ‘John’, 25, and ‘developer’, respectively.
One of the main advantages of using a dictionary in Python is its fast look-up time. Because dictionaries use a special data structure called a hashtable, which allows for constant-time look-ups, accessing a value using its key is efficient even for large dictionaries.
Let’s take a closer look at how a Python dictionary works and how you can use it in your code.
Creating a dictionary in Python
To create a dictionary in Python, we use the dict() function or simply use curly braces { }. The syntax for creating a dictionary using the dict() function is as follows:
dict_name = dict(key1=value1, key2=value2, key3=value3)
The syntax for creating a dictionary using curly braces is:
dict_name = {key1: value1, key2: value2, key3: value3}
Here, the keys are unique and can be of any immutable data type such as strings, integers, tuples, or even other dictionaries. The values, on the other hand, can be of any data type, including strings, integers, lists, or even objects.
Accessing values in a dictionary
To access a value in a dictionary, we use its corresponding key. For example:
print(my_dict[‘name’])