How to Count Tags with Sets and Dictionaries in Python

from collections import Counter
import json


def count_tags(entries):
    """Count tag frequencies across a list of entry dicts, using sets/dicts."""
    tag_counter = Counter()
    all_tags = set()
    for entry in entries:
        tags = set(entry["tags"])
        all_tags.update(tags)
        tag_counter.update(tags)
    return dict(tag_counter), sorted(all_tags)


if __name__ == "__main__":
    sample_data = [
        {"title": "Apple pie", "tags": ["baking", "dessert"]},
        {"title": "Beef stew", "tags": ["cooking", "dinner"]},
        {"title": "Fruit salad", "tags": ["dessert", "fresh"]},
        {"title": "Chicken curry", "tags": ["cooking", "spicy", "dinner"]},
    ]

    frequencies, unique = count_tags(sample_data)
    print("Tag frequencies:", frequencies)
    print("Unique tags:", unique)

    with open("tag_output.json", "w") as f:
        json.dump(frequencies, f, indent=2)
    print("Saved tag_output.json")