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How to Normalize a List of Numbers in Python
This Python function normalizes a list of numeric values to the range [0, 1] using min-max scaling, returning a new list and leaving the original unchanged.
def normalize(data):
"""
Normalize a list of numeric values to the range [0, 1].
Returns a new list, leaving the original unchanged.
"""
if not data:
return []
min_val = min(data)
max_val = max(data)
# Handle the edge case where all values are identical
if min_val …How to Normalize a List of Numbers to the 0-1 Range in Python
Scale a list of numbers so the minimum becomes 0 and the maximum becomes 1 using min-max normalization.
def min_max_normalize(values):
"""Normalize a list of numbers to the [0, 1] range."""
if not values:
return []
min_val = min(values)
max_val = max(values)
if min_val == max_val:
return [0.0] * len(values)
return [(x - min_val) / (max_val - min_val) for x in values]
if __name__…How to Validate CLI Integer Option Within a Range in Python
Use argparse with integer type and bounds checking to validate a command-line option falls within a specified min-max range.
import argparse
def main():
parser = argparse.ArgumentParser(description="Validate an integer within a range.")
parser.add_argument("--value", type=int, required=True, help="Integer to validate")
parser.add_argument("--min", type=int, default=0, help="Minimum allowed value")
parser.add_argument("--max…How to Find Gaps Between Sorted Intervals in Python
This code finds gap ranges between sorted intervals using pairwise iteration, returning ranges where no interval covers.
from itertools import pairwise
def find_gaps(intervals):
intervals = sorted(intervals)
gaps = []
for prev, curr in pairwise(intervals):
if prev[1] < curr[0]:
gaps.append((prev[1] + 1, curr[0] - 1))
return gaps
if __name__ == "__main__":
intervals = [(1, 3), (5, 7), (10, 12), (…How to Sort Array by Parity (Even Before Odd) in Python
Rearrange an array so all even numbers appear before all odd numbers using a simple two-list partition approach.
def sort_array_by_parity(nums):
"""
Rearrange the array so that all even integers come first,
followed by all odd integers. The order within even and odd
groups is not required to be sorted.
"""
even = []
odd = []
for num in nums:
if num % 2 == 0:
even.append(nu…How to compress consecutive numbers into range strings in Python
Convert a sorted list of consecutive integers into compact range strings like '1-3', '5-6', and '15'.
def compress_ranges(nums):
"""Convert a list of sorted consecutive numbers into range strings."""
if not nums:
return []
ranges = []
start = prev = nums[0]
for num in nums[1:]:
if num == prev + 1:
prev = num
else:
if start == prev:
…Rearrange array alternately max min in Python
Rearranges a sorted list so its elements alternate between the current maximum and current minimum using two pointers in O(n) time.
def rearrange_alternately(arr):
"""
Rearrange sorted array so elements alternate: max, min, next max, next min...
Returns a new list in O(n) time using O(n) space.
"""
n = len(arr)
result = []
left, right = 0, n - 1
while left <= right:
if left == right:
result.appen…How to Generate Permutations of Length r in Python
Generate all ordered arrangements of length r from a given list of elements using itertools.permutations.
from itertools import permutations
def generate_permutations(elements, r):
"""Generate all r-length permutations of the given elements."""
return list(permutations(elements, r))
if __name__ == "__main__":
elements = ['A', 'B', 'C']
r = 2
result = generate_permutations(elements, r)
print(f"Ele…How to Slice a Generator with islice in Python
Use itertools.islice to take the first n items from any iterable without materializing the whole sequence into a list.
from itertools import islice
def first_n(iterable, n):
"""Return the first n items from an iterable."""
return list(islice(iterable, n))
if __name__ == "__main__":
numbers = range(10, 100) # large iterable
result = first_n(numbers, 5)
print(result) # [10, 11, 12, 13, 14]How to filter even numbers with a Python list comprehension
Build a new list of only the even numbers from 1 to 20 using a single list comprehension with a filter condition.
even_numbers = [num for num in range(1, 21) if num % 2 == 0]
print(even_numbers)How to Split PDF Pages into Ranges in Python
Simulates splitting a PDF into page ranges by validating and returning structured range splits for automation workflows.
import os
def split_pdf_ranges(pdf_name, num_pages, ranges):
"""
Simulates splitting a PDF by returning the page ranges that would be split.
Args:
pdf_name (str): Name of the PDF file.
num_pages (int): Total number of pages in the PDF.
ranges (list of tuple): List of (start, end) …How to Write an IP Block List to hosts.deny in Python
This Python script validates a list of IP addresses and CIDR ranges, then writes them to a hosts.deny file to block connections at the TCP wrapper level.
from ipaddress import ip_network
def write_hosts_deny(ip_list, output_file="hosts.deny"):
with open(output_file, "w") as f:
for ip in ip_list:
try:
ip_network(ip)
f.write(f"ALL: {ip}\n")
except ValueError:
continue
print(f"Written…How to Filter Data in Python
Filter a list of dictionaries by exact key-value matches or numerical ranges using concise list comprehensions.
from typing import List, Dict, Any
def filter_data(
data: List[Dict[str, Any]], key: str, value: Any
) -> List[Dict[str, Any]]:
"""Return records where data[key] equals value."""
return [record for record in data if record.get(key) == value]
def filter_by_range(
data: List[Dict[str, Any]], key: str…How to Squash Commits Range into One in Python
A mock script that displays the last N git commits as a single squashed commit, showing original commit subjects.
import subprocess
import re
def squash_last_commits(count):
"""Mock squashing the last N commits into one by display."""
git_log = subprocess.run(
["git", "log", f"-{count}", "--pretty=format:%h %s"],
capture_output=True, text=True
)
if git_log.returncode != 0:
return "Git comm…How to Validate AWS Security Group Ingress Rules in Python
Validates AWS security group ingress rules (protocol, port ranges, CIDR, description) and returns a list of errors or OK.
from dataclasses import dataclass
from typing import List, Optional
@dataclass
class SecurityGroupRule:
protocol: str
port_range: tuple
cidr: str
description: str = ""
def validate_ingress_rule(rule: SecurityGroupRule) -> List[str]:
"""Validate a security group ingress rule against common AWS pat…How to Test Hypotheses with Property-Based Check in Python
A Python search that checks an integer property (palindrome divisible by digit sum) and returns the first counterexample within a range, with exactly reproduced output from the code.
def is_property_satisfied(n):
"""
Demonstrates a mathematically inspired property:
checks whether n is both a palindrome and divisible by its digit sum.
"""
s = str(n)
if s != s[::-1]:
return False
digit_sum = sum(int(d) for d in s)
return digit_sum != 0 and n % digit_sum == 0
…How to Build an Append-Only Event Store in Python
Implement a simple append-only event store class that stores events in a list and supports retrieval by index range.
class EventStore:
def __init__(self):
self._events = []
def append(self, event):
"""Append an event to the store."""
self._events.append(event)
def get_events(self, start=0, end=None):
"""Return events from start index to end (exclusive)."""
return self._events[sta…How to Validate Data in Python for Beginners
A beginner-friendly Python class for validating required fields, types, ranges, and allowed choices in dict payloads.
import json
from typing import Any, Dict, List, Optional, Union
class Validator:
"""A simple validate data helper designed for beginners."""
def __init__(self, data: Union[Dict[str, Any], List[Any]]):
self.data = data
self.errors: Dict[str, str] = {}
def validate_required(self, field: s…How to Build a Redis Leaderboard with ZREVRANGE in Python
Build a sorted leaderboard by storing player scores as a Redis sorted set and reading the top scores with ZREVRANGE in Python.
import redis
import random
# Connect to local Redis (ensure Redis is running on localhost:6379)
r = redis.Redis(host="localhost", port=6379, db=0, decode_responses=True)
# Clear any existing test data
r.delete("game_scores")
# Simulate player scores
players = ["alice", "bob", "charlie", "dave", "eve"]
for player in…How to Use Redis ZADD and ZRANGE in Python
Add members to a Redis sorted set with ZADD and retrieve them in score order with ZRANGE in Python.
import redis
client = redis.Redis(host='localhost', port=6379, db=0)
client.delete('scores')
members = {'alice': 30, 'bob': 20, 'carol': 50}
for name, score in members.items():
client.zadd('scores', {name: score})
result = client.zrange('scores', 0, -1)
print(result)How to Link Parent and Child Span Elements in Python
This code defines a lightweight mock element class and a function that links child elements to a parent when their ranges are nested within the parent's range.
class MockElement:
def __init__(self, name, start, end, children=None):
self.name = name
self.start = start
self.end = end
self.children = children or []
def __repr__(self):
return f"MockElement({self.name}, {self.start}-{self.end})"
def link_parent_child(parent, chil…How to Mock HTTP Client Latency in Python
Simulate outbound HTTP request latency with configurable ranges to test timeouts, retries, and SLO monitoring without external services.
import time
import random
def mock_latency(host: str, min_ms: int = 100, max_ms: int = 500) -> dict:
"""Simulate an outbound HTTP request with mock latency."""
latency_ms = random.randint(min_ms, max_ms)
start = time.perf_counter()
time.sleep(latency_ms / 1000)
elapsed_ms = (time.perf_counter() - …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 …Rebalance Shard Ranges Across Nodes in Python
A mock rebalancing function that shuffles shard ranges and distributes them evenly across nodes using round-robin assignment.
import random
from dataclasses import dataclass
@dataclass
class Shard:
id: int
start: int
end: int
def rebalance_shards(shards: list[Shard], node_count: int) -> dict[int, list[Shard]]:
"""Mock rebalancing of shard ranges across nodes."""
all_ranges = [(s.start, s.end) for s in shards]
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