Dictionaries & sets
Key–value maps, uniqueness, counting, grouping, and fast lookups.
How to Count Tags with Sets and Dictionaries in Python
Count tag frequencies and collect unique tags from a list of dictionaries using Counter and sets 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(ta…How to Filter a List of Dictionaries by Category in Python
Filter a list of dictionaries to include only records whose category is in an allowed set.
def filter_data(records, categories):
"""Return only records whose category is in the allowed set."""
allowed = set(categories)
filtered = []
for record in records:
if record["category"] in allowed:
filtered.append(record)
return filtered
if __name__ == "__main__":
data = …How to Group Data by Category in Python with a Split Data Helper
This code groups a list of (category, item) pairs into a dictionary where each key is a category and each value is a list of items belonging to that category.
def split_data(categories):
"""
Group data items into buckets based on a key function.
Returns a dict where keys are bucket names and values are lists of items.
"""
buckets = {}
for category, item in categories:
if category not in buckets:
buckets[category] = []
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Dictionaries & sets — Python code examples
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