Python Dictionaries

# Python Dictionary Operations Example
# Initialize dictionary with current key-value pairs
{ = true
    "name": "Alice",
    "age": 25,
    "city": "NYC"
}
# Current state: 3 key-value pairs
# Dictionary length: len(my_dict) = 3
# Key Constraints: Keys must be immutable (strings, numbers, tuples)
# Valid keys: 'name', 42, (1, 2), True
# Invalid keys: ['list'], {'dict': 'value'}
# === BASIC OPERATIONS ===
# Access value by key
# my_dict["name"] returns "Alice"
# my_dict["age"] returns 25
# my_dict["city"] returns "NYC"
# === DICTIONARY METHODS ===
# Get all keys, values, and items
my_dict.keys()      # dict_keys(['name', 'age', 'city']) = true
my_dict.values()  # dict_values(["Alice", 25, "NYC"]) = true
my_dict.items()    # dict_items([(key, value), ...]) = true
# Safe access with default values
my_dict.get("key", "default")  # Returns "default" if key not found = true
# === NESTED DICTIONARIES ===
# Multi-level dictionary access
{ = true
    "user": {"name":"Alice","age":25},
    "settings": {"theme":"dark","notifications":true}
}
# Access nested values
# nested_dict["user"]["name"] returns the name
# nested_dict.get("user", {}).get("age", 0) for safe access
# === PERFORMANCE NOTES ===
# Dictionary lookup is O(1) average case due to hashing
# Much faster than list search which is O(n)
# Display dictionary
print(f"Dictionary: {my_dict}")
print(f"Size: {len(my_dict)} key-value pairs")