Dictionary In Python

In Python, Dictionary is a built-in data structure that stores a collection of key-value pairs.

Dictionaries are unordered, mutable, and can contain elements of different data types.

Each element in a dictionary is accessed by its key rather than by its index.

Here's how to work with dictionaries in Python:

Creating a Dictionary:

We can create a dictionary by enclosing comma-separated key-value pairs within curly braces {}.

Example:

# Syntax
dictVar = {}

# Checking Type of Variable with Empty dictionary object
print(type(dictVar)) # Output: <class 'dict'>

your_dict = {'name': 'Alice', 'age': 24, 'city': 'London'}

# Printing dictionary variable
print(your_dict) # Output: {'name': 'Alice', 'age': 24, 'city': 'London'}

# Checking Type of Variable
print(type(your_dict)) # Output: <class 'dict'>

Accessing Elements:

We can access elements of a dictionary by specifying the key within square brackets [].

Example:

your_dict = {'name': 'Alice', 'age': 24, 'city': 'London'}

print(your_dict['name'])   # Output: 'Alice'
print(your_dict['age'])    # Output: 24
print(your_dict['city'])    # Output: 'London'

Modifying Elements:

We can modify the value associated with a key in a dictionary by assigning a new value to it.

Example:

your_dict = {'name': 'Alice', 'age': 24, 'city': 'London'}

your_dict['age'] = 42
your_dict['city'] = 'New York'

print(your_dict)   # Output: {'name': 'Alice', 'age': 42, 'city': 'New York'}

Adding Elements:

We can add new key-value pairs to a dictionary by assigning a value to a new key.

Example:

your_dict = {'name': 'Alice', 'age': 24, 'city': 'London'}

your_dict['gender'] = 'Female'
print(your_dict)   # Output: {'name': 'Alice', 'age': 24, 'city': 'London', 'gender': 'Female'}

Removing Elements:

We can remove a key-value pair from a dictionary using the "del" keyword or the "pop()" method.

Example:

your_dict = {'name': 'Alice', 'age': 24, 'city': 'London', 'gender': 'Female'}

# Removing attribute using del keyword
del your_dict['city']
print(your_dict)   # Output: {'name': 'Alice', 'age': 24, 'gender': 'Female'}

# Removing attribute using pop method
removed_value = your_dict.pop('age')
print(removed_value)   # Output: 24

Dictionary Methods:

Dictionaries support various methods for common operations such as accessing keys, values, items and performing membership testing.

Methods are keys(), values() and items() to retreive keys and values and both from dictionary.

Example:

your_dict = {'name': 'Alice', 'age': 24, 'gender': 'Female'}

# Accessing keys, values, and items
print(your_dict.keys())      # Output: dict_keys(['name', 'age', 'gender'])
print(your_dict.values())    # Output: dict_values(['Alice', 24, 'Female'])
print(your_dict.items())     # Output: dict_items([('name', 'Alice'), ('age', 24), ('gender', 'Female')])

Checking Attribute Exist in Tuple:

key name followed by `in` keyword and tuple collection, we can check key exists in our tuple collection.

Example:

your_dict = {'name': 'Alice', 'age': 24, 'gender': 'Female'}

# Checking Attributes Exists in Tuple
print('name' in your_dict)   # Output: True
print('city' in your_dict)   # Output: False

Note:

Dictionaries are widely used in Python for tasks such as storing key-value pairs, representing mappings, and organizing data in a structured manner.

They are efficient for lookups and are an essential tool in Python programming.

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