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Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
How to Make a Git Commit Heatmap by Hour in Python
Parse a git log output and count commits by weekday and hour, then print a compact heatmap table.
import re
from collections import Counter
from datetime import datetime
def parse_commits(log_text):
"""Parse git log lines and count commits by (weekday, hour)."""
pattern = re.compile(r"^Date:\s+(.+)$")
counts = Counter()
for line in log_text.splitlines():
match = pattern.match(line)
…Mock ECS Task Run Stop Status Dict in Python
Build a mock ECS task status dictionary with RUNNING/STOPPED states using the standard library.
from datetime import datetime, timezone
def mock_ecs_task_status(task_id: str, state: str = "RUNNING") -> dict:
"""Return a mock ECS task status dictionary."""
return {
"taskArn": f"arn:aws:ecs:us-east-1:123456789012:task/cluster/{task_id}",
"taskDefinition": "arn:aws:ecs:us-east-1:1234567890…Data Conversion Helper Functions in Python
A set of beginner-friendly helper functions to convert between JSON strings and Python data, parse dates, and read/write files using pathlib.
from datetime import datetime
from pathlib import Path
import json
def to_json(data, indent=2):
"""Convert Python data to pretty-printed JSON string."""
return json.dumps(data, indent=indent, default=str)
def from_json(json_string):
"""Parse JSON string back into Python data."""
return json.loads(jso…How to Format Data with Python's datetime and JSON Helpers
A beginner-friendly set of helper functions to format dates and safely read/write JSON files in Python.
from datetime import datetime
from pathlib import Path
import json
def format_today(pattern: str = "%Y-%m-%d") -> str:
"""Return today's date formatted with the given pattern."""
return datetime.now().strftime(pattern)
def load_json(file_path: str) -> dict:
"""Read and parse a JSON file safely."""
…How to freeze time in Python tests with freezegun
Use the freezegun decorator to freeze datetime.now() at a fixed timestamp so tests that depend on current time run deterministically.
from datetime import datetime
from freezegun import freeze_time
@freeze_time("2024-01-15 12:30:00")
def test_frozen_time():
now = datetime.now()
return now
if __name__ == "__main__":
result = test_frozen_time()
print(result)Mock datetime with time-machine in Python
Use the time-machine library to travel to a fixed datetime when running tests or scripts, mocking datetime.utcnow().
from time_machine import travel
from datetime import datetime
@travel("2020-01-01 10:30:00")
def check_date():
return datetime.utcnow()
if __name__ == "__main__":
print(check_date())Mock datetime.now to freeze time in Python
Use unittest.mock.patch to replace datetime.now with a fixed value so your code always sees the same time during tests.
from datetime import datetime
from unittest.mock import patch
def current_message():
now = datetime.now()
return f"Current time: {now:%Y-%m-%d %H:%M:%S}"
if __name__ == "__main__":
with patch("__main__.datetime") as mock_dt:
mock_dt.now.return_value = datetime(2024, 3, 15, 10, 30, 0)
prin…How to Implement an Outbox Table Poll Publisher in Python
This code simulates an outbox pattern with a class that polls for pending records and publishes them as JSON messages, removing only those that are due.
import time
import json
from dataclasses import dataclass, asdict
from datetime import datetime, timedelta
@dataclass
class OutboxRecord:
id: int
topic: str
payload: dict
created_at: datetime
class OutboxPollPublisher:
def __init__(self, poll_interval_seconds=1):
self.poll_interval = poll…How to Serialize and Deserialize JSON Event Payloads in Python
Define an EventPayload class with custom to_json and from_json methods to convert event objects to JSON strings and back, using datetime parsing.
import json
from datetime import datetime
class EventPayload:
def __init__(self, event_id, event_type, timestamp, data):
self.event_id = event_id
self.event_type = event_type
self.timestamp = timestamp
self.data = data
def to_json(self):
return json.dumps({
…How to Mock Daily and Monthly Quota Counters in Python
Track daily and monthly API call usage with automatic resets, quota checks, and limits using a Python class.
import random
from datetime import datetime, timedelta
class QuotaCounter:
def __init__(self, daily_limit=1000, monthly_limit=20000):
self.daily_limit = daily_limit
self.monthly_limit = monthly_limit
self.daily_usage = 0
self.monthly_usage = 0
self.current_day = datetime.n…Check if a Timestamp Falls in a Daily Maintenance Window in Python
A small Python function that returns True when a datetime falls inside a daily maintenance window, and a demo printing yes/no for sample timestamps.
from datetime import datetime, timedelta
from zoneinfo import ZoneInfo
def in_maintenance_window(now: datetime, start_hour: int = 2, duration_hours: int = 4) -> bool:
"""Return True if 'now' falls inside the daily maintenance window."""
day_start = now.replace(hour=start_hour, minute=0, second=0, microsecond…Generate Synthetic CPU Utilization Metrics in Python
Creates realistic time-series CPU utilization samples with timestamps, noise, and output as structured JSON for observability demos and testing.
from datetime import datetime, timedelta
import random
import json
def generate_metric_samples(base_value, noise, count=60, interval_minutes=1):
"""Generate realistic CPU utilization samples for a given time window."""
timestamps = []
values = []
now = datetime.utcnow()
start_time = now - timede…Session window gap mock in Python
Group sorted timestamps into sessions where any gap between consecutive events exceeds a threshold starts a new session.
from datetime import datetime, timedelta
def session_windows(timestamps, gap_seconds=300):
"""Group timestamps into sessions where gaps > gap_seconds start new sessions."""
if not timestamps:
return []
# Sort timestamps chronologically to ensure correct windowing
timestamps = sorted(timestam…How to Mock Cron Schedule in Python
Compute the next scheduled run time for a cron expression using a pure-Python mock parser.
import re
from datetime import datetime, timedelta
class CronMock:
def __init__(self, expression):
self.expression = expression
self.minutes = self._parse_field(expression.split()[0], 0, 59)
self.hours = self._parse_field(expression.split()[1], 0, 23)
self.days = self._parse_field(…How to Mock an Exposure Event Log Record in Python
Generate a realistic exposure event record with UUID, UTC timestamp, and risk level for testing or experimentation.
import uuid
from datetime import datetime, timezone
def mock_exposure_event(person_id: str, location: str, duration_minutes: int) -> dict:
return {
"event_id": str(uuid.uuid4()),
"person_id": person_id,
"location": location,
"duration_minutes": duration_minutes,
"timestamp…How to Convert Data with Scaling for Database Optimization in Python
A beginner-friendly helper that normalizes and scales numeric fields in a list of dicts, reducing storage footprint for database efficiency.
import json
from datetime import datetime
def convert_data(data: list[dict], scale_factor: int = 1) -> list[dict]:
"""Convert a list of dicts to a scaled, normalized format for database efficiency."""
converted = []
for row in data:
normalized = {}
for key, value in row.items():
…How to Mock Date Sharding by Range in Python
Split a date interval into fixed-size contiguous shards, returning each window as an ISO date string pair.
from datetime import date, timedelta
def shard_ranges(start_date, end_date, shard_days=7):
if start_date > end_date:
raise ValueError("start_date cannot be after end_date")
shards = []
current = start_date
while current <= end_date:
shard_end = min(current + timedelta(days=shard_days …How to Mock a TLS Certificate Rotation Schedule in Python
Simulate a TLS certificate rotation schedule with a Python class that tracks last and next rotation dates and decides when to rotate.
import datetime
import random
import time
class CertRotator:
def __init__(self, cert_name, rotation_days=30):
self.cert_name = cert_name
self.rotation_days = rotation_days
self.last_rotated = datetime.date.today() - datetime.timedelta(days=random.randint(10, 25))
self.next_rotatio…Generate a Mock Artifact Version Tag in Python
Creates a mock build artifact version tag from a branch name and build number, with a date stamp.
import re
from datetime import datetime
def mock_version_tag(branch_name: str, build_number: int) -> str:
"""Generate a mock build artifact version tag from branch and build number."""
branch_slug = re.sub(r'[^a-zA-Z0-9]+', '-', branch_name).strip('-').lower()
date_part = datetime.utcnow().strftime('%Y%m%…How to build a maintenance mode page in Python
Mock a service maintenance status page that computes remaining downtime and lists affected features from a simple class.
from datetime import datetime
class MaintenanceMode:
"""Mock a maintenance mode status page for a service."""
def __init__(self, service_name: str, scheduled_end: str):
self.service_name = service_name
self.scheduled_end = datetime.fromisoformat(scheduled_end)
self.affected_featur…Browse by section
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Guide: free Python code samples library
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