Reference library

Dictionaries & sets

Key–value maps, uniqueness, counting, grouping, and fast lookups.

6 matches

Group Data by Key in Python with Dictionaries and Sets

Group items into a dictionary of sets using a key function, a beginner-friendly pattern for organizing data by categories.

grouping dictionaries sets

Python

def group_data(items, key_func):
    """Group items into a dictionary of sets based on a key function."""
    grouped = {}
    for item in items:
        key = key_func(item)
        if key not in grouped:
            grouped[key] = set()
        grouped[key].add(item)
    return grouped


if __name__ == "__main__":
 …

15 0 Open

Dictionaries & sets easy

How to Create a Dict from Two Parallel Lists in Python (zip)

Build a dictionary by pairing elements from two parallel lists using Python's built-in zip function and dict constructor.

dictionary zip lists

Python

keys = ["name", "age", "city"]
values = ["Alice", 30, "New York"]

result = dict(zip(keys, values))
print(result)

13 0 Open

Dictionaries & sets easy

How to Group a List of Dictionaries by Key in Python

Group a list of dictionaries by a specified key field using dict.setdefault to build a dictionary of lists.

dictionaries grouping setdefault

Python

def group_by_key(records, key):
    grouped = {}
    for record in records:
        grouped.setdefault(record[key], []).append(record)
    return grouped

if __name__ == "__main__":
    data = [
        {"name": "Alice", "dept": "engineering"},
        {"name": "Bob", "dept": "sales"},
        {"name": "Carol", "dept"…

14 0 Open

Dictionaries & sets easy

How to Use Dictionaries and Sets in Python for Beginners

Demonstrates Python dictionary operations and set operations with examples, including access, modification, defaults, and set algebra.

dictionary set beginner

Python

def demonstrate_collections():
    # Dictionary basics
    student = {
        "name": "Alice",
        "age": 20,
        "courses": ["Math", "Physics"]
    }
    print("Dictionary:", student)

    # Access and modify
    student["age"] = 21
    student["grade"] = "A"
    print("Modified:", student)

    # Get with d…

11 0 Open

Dictionaries & sets easy

How to Use Dictionaries and Sets in Python for Beginners

Introduces Python dictionaries and sets with practical examples including creating, modifying, and performing set operations, plus a word-frequency counter.

dictionaries sets data structures

Python

def demonstrate_dict_sets():
    # Create a dictionary with basic info
    person = {
        "name": "Alice",
        "age": 30,
        "city": "New York"
    }
    print("Dictionary:", person)

    # Access and modify dictionary values
    person["age"] = 31
    person["email"] = "alice@example.com"
    print("Afte…

15 0 Open

Dictionaries & sets easy

How to merge dictionaries and sets in Python

Merges multiple dictionaries with the ** unpacking operator and combines sets using union operations into a single structure.

dict-merge set-union unpacking

Python

def merge_dictionaries_and_sets(school_dict, teacher_dict, course_dict, student_sets):
    """
    Merges multiple dictionaries and sets into a single combined structure.
    Demonstrates dict unpacking and set union operations.
    """
    # Merge all dictionaries using the unpacking operator (Python 3.9+)
    merged…

12 0 Open

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