Dictionary in Python

In a NoSQL database, data structure varies based on requirements. In a List, data is stored in a specific order, and the position of each element matters. For example, to access the first element in a List, you retrieve the value at index 0, which is predictable due to the ordered nature of Lists.

However, when the order of data is not important, a Dictionary (or key-value store) is more suitable. Consider a scenario where you need to store user information like age, address, first name, and last name. In this case, the sequence of these fields doesn’t matter. With a Dictionary, you can directly access a specific value using its key, such as retrieving the first name by querying the "first_name" key, without needing to know the last name or other fields.

Key differences:

• In a List, values are stored with predefined, sequential indices (0, 1, 2, ...), and you access data by its position.
• In a Dictionary, you define custom keys mapped to values, allowing direct access to data via the key, regardless of order.

Thus, for scenarios where you need flexible, key-based access to data without relying on order, a Dictionary is the preferred choice.

Coffee Menu in Python — Dictionary Operations

1. Creating a Coffee Menu (Dictionary)

coffee_menu = {
    "Espresso": "Bold shot!",
    "Latte": "Creamy delight",
    "Cappuccino": "Frothy classic",
    "Mocha": "Choco-coffee",
    "ColdBrew": "Smooth chill",
    "Americano": "Espresso + water",
    "Macchiato": "Espresso kiss"
}

print(coffee_menu)

1. Accessing a Value (Using Key)

print(coffee_menu['Espresso'])

Output:

Bold shot!

1. Changing a Value

   coffee_menu['Espresso'] = 'Tiny Thunder'
   print(coffee_menu)
   

Output:

{
    'Espresso': 'Tiny Thunder',
    'Latte': 'Creamy delight',
    'Cappuccino': 'Frothy classic',
    'Mocha': 'Choco-coffee',
    'ColdBrew': 'Smooth chill',
    'Americano': 'Espresso + water',
    'Macchiato': 'Espresso kiss'
}

1. Iterating Over the Dictionary

• Only Keys

for coffee in coffee_menu:
    print(coffee)

Output:

Espresso
Latte
Cappuccino
Mocha
ColdBrew
Americano
Macchiato

• Keys and Values (Method 1)

  for coffee in coffee_menu:
  print(coffee, ":", coffee_menu[coffee])
  

• Keys and Values (Method 2)

  for key, value in coffee_menu.items():
  print(key, ":", value)
  

1. Adding an Item

   coffee_menu["Flat White"] = "Velvety Smooth"
   print(coffee_menu)
   

2. Removing Items

• Using pop(key)

  coffee_menu.pop('Espresso')
  print(coffee_menu)
  

Output:

{
    'Latte': 'Creamy delight',
    'Cappuccino': 'Frothy classic',
    'Mocha': 'Choco-coffee',
    'ColdBrew': 'Smooth chill',
    'Americano': 'Espresso + water',
    'Macchiato': 'Espresso kiss'
}

• Using popitem()

Removes the last inserted item.

coffee_menu.popitem()
print(coffee_menu)

Example Output:

{
    'Espresso': 'Bold shot!',
    'Latte': 'Creamy delight',
    'Cappuccino': 'Frothy classic',
    'Mocha': 'Choco-coffee',
    'ColdBrew': 'Smooth chill',
    'Americano': 'Espresso + water'
}

⚠️ Note: If the dictionary is empty, popitem() will raise a KeyError.

• Using del Statement

  del coffee_menu["Latte"]
  print(coffee_menu)
  

📝 Note:
Each operation was done individually for demonstration, so dictionary contents might look different in each output. In a real program, you'd typically chain these actions as needed.