script_16.py - List Searching

Code

See script_16.py for full code.

Explanation

Line 20: prices = [p["price"] for p in products] - List comprehension extracting one field - p is dict, p["price"] is value - Creates list of integers from list of dicts

Line 22: print(f"Is $300 in prices? {300 in prices}") - in operator for membership testing - Linear search O(n) - Returns boolean

Line 29: def find_by_id(products, target_id): - Function to find first match

Line 31: for product in products: - Iterates until match found

Line 32: if product["id"] == target_id: - Compares dict value

Line 33: return product - Exits function immediately - Returns the matching dict

Line 34: return None - If loop completes without return - Indicates "not found"

Line 40: def find_product(products, **criteria): - **criteria captures keyword arguments as dict - Allows flexible search: find_product(name="Laptop") or find_product(category="furniture", price=300)

Line 41: return next(...) - next() gets first element from iterator - Second argument is default if iterator empty

Line 42: (p for p in products if all(p.get(k) == v for k, v in criteria.items())) - Generator expression (parentheses, not brackets) - all() returns True if all conditions True - p.get(k) safely accesses dict (returns None if key missing) - criteria.items() is dict of search criteria - Checks all criteria must match

Line 49: electronics = [p for p in products if p["category"] == "electronics"] - List comprehension for filtering - Returns all matches (not just first)

Line 59: idx = numbers.index(30) - .index() finds first occurrence - Returns integer position - Raises ValueError if not found

Line 65: all_indices = [i for i, x in enumerate(numbers) if x == 30] - enumerate provides indices - Comprehension filters matching positions - Returns list of all indices

Line 71: import bisect - bisect module for binary search

Line 73: sorted_prices = sorted(prices) - Binary search requires sorted data - sorted() creates new sorted list

Line 77: idx = bisect.bisect_left(sorted_prices, target) - .bisect_left() finds insertion point - O(log n) complexity (fast) - Returns index where target should be inserted - Maintains sorted order

Line 78: if idx < len(sorted_prices) and sorted_prices[idx] == target: - Verifies element actually exists at that position - bisect only finds position, must check value

Line 84: has_expensive = any(p["price"] > 1000 for p in products) - any() returns True if any element satisfies condition - Generator expression (not list) - Short-circuits (stops at first True)

Line 87: all_positive_prices = all(p["price"] > 0 for p in products) - all() returns True if all elements satisfy condition - Short-circuits (stops at first False)