Reference library

Dictionaries & sets

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

5 matches

Build a Case-Insensitive Dict with a Wrapper Class in Python

Create a custom dict subclass that treats keys as case-insensitive by normalizing them to lowercase, with a full set of common dict methods.

dictionary case-insensitive wrapper

Python

class CaseInsensitiveDict:
    def __init__(self, data=None):
        self._data = {}
        if data:
            self.update(data)

    def __setitem__(self, key, value):
        self._data[str(key).lower()] = value

    def __getitem__(self, key):
        return self._data[str(key).lower()]

    def __delitem__(sel…

13 0 Open

Dictionaries & sets medium

How to Build a Two-Way Dictionary in Python

Implement a BiDict class that supports both forward key-to-value and reverse value-to-key lookups with a simple add, delete, and update API.

dictionary bidirectional class

Python

class BiDict:
    def __init__(self, data=None):
        self.forward = {}
        self.backward = {}
        if data:
            self.update(data)

    def update(self, data):
        for key, value in data.items():
            self[key] = value

    def __setitem__(self, key, value):
        self.forward[key] = val…

11 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)

12 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 medium

LRU Cache with OrderedDict in Python

Implement an LRU cache using collections.OrderedDict to track insertion order and evict the least-recently-used item when capacity is exceeded.

lru-cache ordereddict caching

Python

from collections import OrderedDict

class LRUCache:
    def __init__(self, capacity):
        self.capacity = capacity
        self.cache = OrderedDict()

    def get(self, key):
        if key not in self.cache:
            return -1
        self.cache.move_to_end(key)
        return self.cache[key]

    def put(sel…

14 0 Open

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