PYTHON
Dynamic Dictionary Creation with Comprehensions
Master dictionary comprehensions in Python to efficiently create new dictionaries by transforming or filtering iterable items, a powerful technique for web data processing.
# Example 1: Creating a dictionary from a list of key-value pairs
items = [('apple', 3), ('banana', 5), ('orange', 2)]
fruit_counts = {fruit: count for fruit, count in items}
print(f"Fruit counts: {fruit_counts}")
# Example 2: Transforming values from an existing dictionary
price_list = {'laptop': 1200, 'mouse': 25, 'keyboard': 75}
discounted_prices = {item: price * 0.9 for item, price in price_list.items()}
print(f"Discounted prices (10% off): {discounted_prices}")
# Example 3: Filtering items based on a condition
high_value_items = {item: price for item, price in price_list.items() if price > 50}
print(f"High-value items: {high_value_items}")
# Example 4: Creating a dictionary from two lists
keys = ['user_id', 'username', 'email']
values = [101, 'john_doe', '[email protected]']
user_data = {key: value for key, value in zip(keys, values)}
print(f"User data: {user_data}")
How it works: Dictionary comprehensions provide a concise way to create dictionaries from any iterable. They allow you to define key-value pairs using an expression, optionally including conditional logic to filter items. This is extremely useful in web development for tasks like processing form submissions, parsing API responses, or generating configuration objects dynamically, making your code more compact and readable.