Reference library

Dictionaries & sets

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

3 matches

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.

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

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 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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