python dict

Python dictionary is a built-in data type used to store multiple values in a single variable. It is also known as a map or associative array in some other programming languages. In this article, we will explore the Python dictionary data type, its characteristics, how to create, access, modify, and delete elements from it.

Characteristics of Python Dictionary

1. Unordered: Unlike sequences (lists, tuples), dictionaries are unordered, which means the elements are not stored in any particular order.

2. Mutable: Dictionaries are mutable, which means you can add, delete, or modify elements after the dictionary has been created.

3. Key-Value Pair: The dictionary is a collection of key-value pairs, where each key is unique and associated with a value.

4. Indexed: Dictionaries are indexed using keys instead of numeric indices, unlike lists or tuples.

5. Dynamic: The size of the dictionary can change as elements are added or deleted from it.

6. Unchangeable Keys: The keys in a dictionary are immutable, which means they cannot be changed once they are created. Keys can only be of immutable data types like strings, numbers, or tuples.

Creating a Python Dictionary

To create a dictionary, we use curly braces ({}) with colon (:) separating the key-value pairs. Each key-value pair is separated by a comma (,).

Example:

# Creating a dictionary
student = {"name": "John", "age": 25, "city": "New York"}

In this example, we have created a dictionary student with three key-value pairs, "name", "age", and "city".

Accessing Elements in a Python Dictionary

To access the elements in a dictionary, we use the key associated with it. The key serves as an index for the value.

Example:

# Accessing elements in a dictionary
print(student["name"]) # Output: John
print(student["age"]) # Output: 25

In this example, we have accessed the elements of the dictionary student using the key.

Modifying Elements in a Python Dictionary

To modify an element in a dictionary, we access it using the key and then assign it a new value.

Example:

# Modifying elements in a dictionary
student["age"] = 26
print(student) # Output: {'name': 'John', 'age': 26, 'city': 'New York'}

In this example, we have modified the age of the student in the dictionary student.

Adding Elements to a Python Dictionary

To add a new element to the dictionary, we use a new key-value pair.

Example:

# Adding elements to a dictionary
student["phone"] = "123-456-7890"
print(student) # Output: {'name': 'John', 'age': 26, 'city': 'New York', 'phone': '123-456-7890'}

In this example, we have added a new key-value pair to the dictionary student.

Deleting Elements from a Python Dictionary

To delete an element from a dictionary, we use the del keyword with the key.

Example:

# Deleting elements from a dictionary
del student["phone"]
print(student) # Output: {'name': 'John', 'age': 26, 'city': 'New York'}

In this example, we have deleted the "phone" key-value pair from the dictionary student.