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How to Filter Git History to Remove Secret File Entries in Python
A pure-Python mock that filters a repository's history to drop any commit that touched a secret file, so you can plan a cleanup before rewriting Git history.
from pathlib import Path
import json
def filter_history(history, secret_path):
"""Remove entries that touch the secret file."""
return [entry for entry in history if secret_path not in entry["files"]]
if __name__ == "__main__":
repo_history = [
{"commit": "a1b2c3", "message": "Add app", "files": …How to Vectorize a Function with a Pure Python Fallback
Create a decorator that calls a scalar function directly for a single value and routes list inputs to a pure-Python fallback for vectorized processing without NumPy.
import math
def fallback_vectorize(func, fallback=None):
"""Vectorize a scalar function with a pure-Python fallback for lists."""
if fallback is None:
fallback = lambda x: [func(i) for i in x]
def wrapped(*args):
if len(args) == 1 and isinstance(args[0], (list, tuple)):
retur…How to Implement collect_list in Python
Group rows by a key and collect all corresponding values into a list — a pure-Python mock of Spark's collect_list aggregation.
from collections import defaultdict
def collect_list(rows, key_field, value_field):
grouped = defaultdict(list)
for row in rows:
grouped[row[key_field]].append(row[value_field])
return dict(grouped)
if __name__ == "__main__":
data = [
{"dept": "sales", "emp": "alice"},
{"dept"…StandardScaler mock in Python
A pure-Python StandarScaler class that standardizes features to zero mean and unit variance without sklearn.
import math
class StandardScaler:
def __init__(self):
self.mean_ = None
self.std_ = None
def fit(self, X):
n = len(X)
self.mean_ = [sum(col) / n for col in zip(*X)]
self.std_ = []
for col in zip(*X):
variance = sum((x - self.mean_[i]) ** 2 for i, x …Browse by section
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Guide: free Python code samples library
Copy-ready Python snippets for learners and developers
PythonSkillset code samples are short, focused examples organised by topic and difficulty. Every snippet is server-rendered HTML — readable by search engines and easy to copy. Open any sample, read the notes, copy the code, then press Try in editor to run it in the browser with Pyodide.
How to use this library
- Pick a topic section — strings, lists, files, functions, and more
- Open a sample, read How it works, and copy the code block
- Run it in the IDE, tweak values, then take a related quiz or tutorial lesson
Samples vs tutorials and challenges
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.