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Dictionaries & sets

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

4 matches

Flatten a Nested Dict to Dot Notation Keys in Python

Recursively flatten a nested dictionary into a flat dictionary with dot-separated keys using a small recursive function.

dict flatten recursion

Python

def flatten_dict(nested, parent_key='', sep='.'):
    items = {}
    for key, value in nested.items():
        new_key = f"{parent_key}{sep}{key}" if parent_key else key
        if isinstance(value, dict):
            items.update(flatten_dict(value, new_key, sep))
        else:
            items[new_key] = value
    …

11 0 Open

Dictionaries & sets easy

How to Count Co-occurrence Pairs in Python with Nested Dictionaries

This code counts how often any two items appear together in the same group, using a nested defaultdict keyed by item pairs.

dictionaries co-occurrence counter

Python

from itertools import combinations
from collections import defaultdict

def count_cooccurrences(items_per_group):
    cooccurrence = defaultdict(lambda: defaultdict(int))
    for group in items_per_group:
        for a, b in combinations(sorted(group), 2):
            cooccurrence[a][b] += 1
            cooccurrence[b…

12 0 Open

Dictionaries & sets easy

How to Set Nested Dict Value Creating Missing Keys in Python

Set a value deep inside a nested dictionary, automatically creating any missing intermediate dicts along the path.

dictionary nested mutation

Python

def set_nested_value(d, keys, value):
    """
    Set a value in a nested dict, creating missing intermediate keys.
    
    Args:
        d: The dict to modify
        keys: Iterable of keys forming the path (e.g., ['a', 'b', 'c'])
        value: The value to set at the final key
    """
    current = d
    for key i…

13 0 Open

Dictionaries & sets easy

How to convert string values to int or float in Python dicts

Recursively convert string values in nested dicts and lists to ints or floats when possible, leaving other strings untouched.

dict type-conversion recursion

Python

def coerce_str_values(data):
    """Recursively convert string values that look like ints or floats."""
    if isinstance(data, dict):
        return {key: coerce_str_values(val) for key, val in data.items()}
    elif isinstance(data, list):
        return [coerce_str_values(item) for item in data]
    elif isinstance…

13 0 Open

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