Working with Dictionaries in Python

In Python, dictionaries are used to store data in key-value pairs, where each key is unique. This structure is useful for managing and accessing data where each piece of information can be uniquely identified by a key.

Creating Dictionaries

To create a dictionary in Python, you define a collection of key-value pairs using curly braces {}. Keys can be strings, numbers, or tuples, and values can be of any type.

Python 
# Creating a dictionary
student = {
    "name": "Alice",
    "age": 20,
    "grades": [85, 90, 92]
}

print(student)

Accessing Values

You can access the values in a dictionary by referring to their keys. This allows you to retrieve and manipulate the data stored in the dictionary.

Python 
# Accessing values from the dictionary
print("Student Name:", student["name"])
print("Student Age:", student["age"])
print("Student Grades:", student["grades"])

Adding and Updating Entries

You can add new key-value pairs to an existing dictionary or update the values of existing keys. This flexibility allows you to manage and modify your data easily.

Python 
# Adding a new entry
student["email"] = "alice@example.com"

# Updating an existing entry
student["age"] = 21

print(student)

Deleting Entries

To remove an entry from a dictionary, you use the del statement or the pop() method. This removes the key-value pair from the dictionary.

Python 
# Deleting an entry
del student["email"]

print(student)

Iterating Through a Dictionary

You can loop through a dictionary to access all key-value pairs. This is useful for performing operations on each entry in the dictionary.

Python 
# Iterating through the dictionary
for key, value in student.items():
    print(f"{key}: {value}")

Nested Dictionaries

Dictionaries can contain other dictionaries as values. This allows you to create more complex data structures, such as hierarchical data.

Python 
# Creating a nested dictionary
school = {
    "students": {
        "Alice": {"age": 20, "grades": [85, 90, 92]},
        "Bob": {"age": 22, "grades": [78, 84, 89]}
    },
    "teachers": {
        "Mr. Smith": {"subject": "Math", "years": 10},
        "Ms. Johnson": {"subject": "English", "years": 8}
    }
}

print(school)