Reference library

Dictionaries & sets

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

4 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

Find All Leaf Paths in a Nested Dict in Python

Recursively traverse a nested dictionary and yield every leaf path as a list of keys, including paths to empty dictionaries.

dictionary recursion nested-data

Python

def find_leaf_paths(data, path=None):
    if path is None:
        path = []
    
    if not isinstance(data, dict) or not data:
        yield path
        return
    
    for key, value in data.items():
        yield from find_leaf_paths(value, path + [key])

if __name__ == "__main__":
    nested = {
        "a": 1,
…

13 0 Open

Dictionaries & sets medium

How to Build a TTL Cache Dict in Python

Create a dictionary subclass that automatically expires keys after a fixed time-to-live using timestamps.

dictionary cache ttl

Python

import time

class TTLDict(dict):
    def __init__(self, ttl, *args, **kwargs):
        self.ttl = ttl
        self._expires = {}
        super().__init__(*args, **kwargs)

    def __setitem__(self, key, value):
        super().__setitem__(key, value)
        self._expires[key] = time.time() + self.ttl

    def __geti…

16 0 Open

Dictionaries & sets medium

Unflatten Dot Keys to Nested Dict in Python

Convert a flat dictionary with dot-separated keys into a nested dictionary structure using recursive setdefault loops.

dictionaries nested flatten

Python

def unflatten_dot_keys(flat_dict):
    result = {}
    for flat_key, value in flat_dict.items():
        parts = flat_key.split(".")
        current = result
        for part in parts[:-1]:
            current = current.setdefault(part, {})
        current[parts[-1]] = value
    return result


if __name__ == "__main_…

14 0 Open

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