script_10.py - List Grouping

Code

See script_10.py for full code.

Explanation

Line 8: from collections import defaultdict - defaultdict is dict subclass - Provides default value for missing keys

Line 9: from itertools import groupby - groupby() groups consecutive elements

Line 10: from operator import itemgetter - itemgetter() creates function to extract item

Line 24: grouped_manual = defaultdict(list) - Creates defaultdict with list as default factory - Accessing missing key automatically creates empty list - Type: defaultdict, behaves like dict

Line 26: grouped_manual[log["level"]].append(log) - If key doesn't exist, creates empty list automatically - Then appends to that list - No need to check if key exists first

Line 28: for level, entries in grouped_manual.items(): - .items() returns key-value pairs - entries is a list (the grouped logs)

Line 36: sorted_logs = sorted(logs, key=itemgetter("level")) - itemgetter("level") creates function equivalent to lambda x: x["level"] - More efficient than lambda - Sorts by the "level" key

Line 37: for level, group in groupby(sorted_logs, key=itemgetter("level")): - groupby() groups consecutive equal elements - Requires sorted input (groups only consecutive items) - Returns iterator of (key, group) tuples - group is iterator (must convert to list)

Line 38: entries = list(group) - Converts iterator to list - Iterator can only be consumed once

Line 49: region_totals = defaultdict(lambda: {"total": 0, "count": 0}) - Lambda creates default dict with two keys - Each missing region gets own dict with total and count - Useful for aggregating multiple values