What Is Map Data Type in Python?
In Python, a map is a built-in data type that allows you to store key-value pairs. It is also known as a dictionary or associative array in other programming languages. Maps are incredibly useful when you need to store and retrieve data based on unique keys rather than numeric indices.
Creating a Map
To create a map in Python, you can use curly braces ({}) or the built-in dict() function. Let’s take a look at some examples:
# Using curly braces
my_map = {'name': 'John', 'age': 25, 'country': 'USA'}
# Using dict() function
my_map = dict(name='John', age=25, country='USA')
In both cases, we have created a map with three key-value pairs: ‘name’ with the value ‘John’, ‘age’ with the value 25, and ‘country’ with the value ‘USA’.
Accessing Values in a Map
To access values in a map, you can use square brackets ([]). Let’s see how it works:
my_map = {'name': 'John', 'age': 25, 'country': 'USA'}
print(my_map['name']) # Output: John
print(my_map['age']) # Output: 25
print(my_map['country']) # Output: USA
In this example, we access the values of keys ‘name’, ‘age’, and ‘country’ using square brackets and print them to the console.
Modifying a Map
Maps in Python are mutable, which means you can modify their values or add new key-value pairs after creation. Let’s see some examples:
# Modifying a value
my_map[‘age’] = 30
# Adding a new key-value pair
my_map[‘city’] = ‘New York’
print(my_map)
The output will be:
{'name': 'John', 'age': 30, 'country': 'USA', 'city': 'New York'}
In this example, we modify the value of the ‘age’ key to 30 and add a new key-value pair ‘city’ with the value ‘New York’.
Iterating Over a Map
You can iterate over the keys or values of a map using loops. Let’s see how it works:
# Iterating over keys
for key in my_map:
print(key)
# Iterating over values
for value in my_map.values():
print(value)
# Iterating over key-value pairs
for key, value in my_map.items():
print(key, value)
The output will be:
name
age
country
John
25
USA
name John
age 25
country USA
In these examples, we use different loops to iterate over keys, values, and key-value pairs of the map.
Checking if a Key Exists
You can check if a specific key exists in a map using the in keyword. Here’s an example:
if ‘name’ in my_map:
print(‘Key exists’)
else:
print(‘Key does not exist’)
Key exists
In this example, we check if the key ‘name’ exists in the map and print the corresponding message.
Conclusion
In Python, maps are a powerful data type that allows you to store and retrieve data based on unique keys. With their ability to hold key-value pairs, maps provide efficient ways to organize and manipulate data in your programs.