Reference library

Dictionaries & sets

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

4 matches

How to Parse Data Into Dictionaries and Sets in Python

Parses raw student strings into a dictionary of lists and finds unique courses using a set.

from collections import defaultdict

def parse_students(raw_data):
    """Parse raw student strings into a dictionary of lists."""
    parsed = defaultdict(list)
    for entry in raw_data:
        name, _, course = entry.partition(":")
        parsed[course.strip()].append(name.strip())
    return dict(parsed)

def fi…

12 0 Open

Dictionaries & sets easy

How to Parse Query String to Dict with Duplicate Keys in Python

Convert a URL query string into a Python dictionary, merging duplicate keys into lists while keeping single values as scalars.

query-string dict url-parsing

Python

from urllib.parse import parse_qs


def parse_query_to_dict(query_string):
    parsed = parse_qs(query_string, keep_blank_values=True)
    return {key: values if len(values) > 1 else values[0] for key, values in parsed.items()}


if __name__ == "__main__":
    query = "name=John&name=Jane&age=30&city=&city=Paris&empty…

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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…

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Dictionaries & sets easy

Parse Env Vars into Typed Dict in Python

Convert a list of environment variable names into a dictionary with automatically detected types (bool, int, float, or string), defaulting missing vars to None.

env-vars type-conversion dict

Python

import os
from typing import Any, Dict


def parse_env_vars(env_names: list[str], env: Dict[str, str] | None = None) -> Dict[str, Any]:
    """Parse a list of environment variable names into a typed dict.

    Each variable is parsed as:
    - bool: "true"/"false" (case-insensitive)
    - int: if it can be converted t…

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