Reference library

Python Code Samples

Medium snippets you can copy, study, and run in the browser editor.

8 matches
Errors & debugging medium

How to Diff Two Dicts in Python for Config Drift

Recursively compare two dictionaries and report added, removed, and changed keys with their old and new values for debugging configuration drift.

dict diff config
Python
def diff_dicts(a, b, path=""):
    differences = []

    for key in a.keys() | b.keys():
        new_path = f"{path}.{key}" if path else key

        if key not in a:
            differences.append((new_path, "<missing>", b[key], "added"))
        elif key not in b:
            differences.append((new_path, a[key], "<…
13 0 Open
Dictionaries & sets medium

How to Deep Merge Nested Dicts Recursively in Python

Recursively merge two Python dictionaries, with overlay values taking precedence while preserving nested structures.

dict-merge recursion nested-dicts
Python
def deep_merge(base, overlay):
    """
    Recursively merge two dictionaries.
    Values in 'overlay' take precedence over 'base'.
    """
    result = base.copy()
    
    for key, value in overlay.items():
        if key in result and isinstance(result[key], dict) and isinstance(value, dict):
            result[key…
14 0 Open
Dictionaries & sets medium

Traverse Nested Dict Paths Depth-First in Python

Recursively walk a nested dictionary depth-first and yield each full path from root to leaf as lists.

recursion generators nested-dicts
Python
def depth_first_paths(node, path=None):
    if path is None:
        path = []
    
    if not isinstance(node, dict):
        yield path + [node]
        return
    
    for key, value in node.items():
        new_path = path + [key]
        if isinstance(value, dict):
            yield from depth_first_paths(value, …
13 0 Open
Data pipelines & processing medium

How to perform a star schema join in Python

Denormalize mock fact and dimension tables by building lookup dicts and enriching each sales fact with customer, product, and date attributes.

star-schema data-joins dimensional-modeling
Python
from datetime import date

# Mock dimension tables
customers = [
    {"customer_id": 1, "name": "Alice", "city": "New York"},
    {"customer_id": 2, "name": "Bob", "city": "Los Angeles"},
    {"customer_id": 3, "name": "Carol", "city": "Chicago"},
]

products = [
    {"product_id": 101, "name": "Laptop", "category": "…
12 0 Open
Big data & Spark medium

How to Implement a Mock MapReduce for Word Count in Python

Simulates a MapReduce word count pipeline with mapper, shuffle, and reducer phases using Python dicts and standard library modules.

mapreduce word-count big-data
Python
from collections import defaultdict
import re

def mapper(text):
    """Split text into words and emit (word, 1) pairs."""
    words = re.findall(r'\b\w+\b', text.lower())
    return [(word, 1) for word in words]

def reducer(pairs):
    """Group word-count pairs and sum counts."""
    counts = defaultdict(int)
    fo…
15 0 Open
A/B testing & experimentation medium

How to join assignment logs with outcomes in Python

Merge submission log entries with grading outcomes using left join and full outer join patterns in pure Python.

join data-merge ab-testing
Python
from datetime import datetime, timedelta

class AssignmentLog:
    def __init__(self):
        self.logs = [
            {"assignment_id": 101, "student_id": "S001", "submitted_at": "2024-03-01 10:30:00"},
            {"assignment_id": 101, "student_id": "S002", "submitted_at": "2024-03-02 14:15:00"},
            {"as…
12 0 Open
A/B testing & experimentation medium

Synthetic Control in Python: Mock Example

Implements synthetic control from scratch: learns donor weights via ridge regression on pre-period data, then predicts a counterfactual for the treated unit.

synthetic-control causal-inference numpy
Python
import numpy as np

class SyntheticControl:
    def __init__(self, data, treated_index, pre_periods, post_periods):
        self.data = np.array(data, dtype=float)
        self.treated_index = treated_index
        self.pre_periods = pre_periods
        self.post_periods = post_periods
        
    def fit_weights(sel…
15 0 Open
Production deployment patterns medium

How to Mock Image Signing Cost in Python

Create a deterministic mock signing cost calculator that predicts resource usage for image signatures before real signing infrastructure is staged.

mock signing cost-model
Python
import math
import struct


def sign_image_cost(image_signature: bytes) -> int:
    """Deterministic mock signing cost based on image signature bytes."""
    if not image_signature:
        raise ValueError("Empty image signature")
    digest = 0
    for byte in image_signature:
        digest = (digest * 31 + byte) &…
14 0 Open

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Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.