Python Code
Samples
Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
Automatically Detect Weak Passwords from Large Password Lists in Python
This Python script identifies weak passwords from a list by checking length, common patterns, sequential characters, and uniform characters, returning those that fail the security checks.
import re
COMMON_PASSWORDS_FILE = "common_passwords.txt"
def is_weak(password):
# Check length
if len(password) < 8:
return True
# Check for common patterns
if password.lower() in {"password", "123456", "qwerty", "letmein", "admin", "welcome"}:
return True
# Check for sequential c…Extract Email-Like Tokens from Text in Python
Uses a regular expression to find all email-like tokens in a string, returning them as a list with re.findall.
import re
def extract_email_like_tokens(text):
pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b'
return re.findall(pattern, text)
if __name__ == "__main__":
sample_text = (
"Contact us at support@example.com or sales@company.co.uk. "
"Invalid: hello@world, user@.com, test@do…How to Align Text in Two Columns with ljust in Python
Format pairs of strings into two aligned columns using ljust padding.
items = [
("apple", "red"),
("banana", "yellow"),
("cherry", "dark red"),
("date", "brown")
]
col1_width = max(len(name) for name, _ in items) + 2
for name, color in items:
print(name.ljust(col1_width) + color)How to Check if a String is Alphanumeric in Python
Uses the built-in str.isalnum() method to test whether a string contains only letters and numbers.
def is_alphanumeric(s: str) -> bool:
return s.isalnum()
if __name__ == "__main__":
test_cases = ["Hello123", "Hello World", "12345", "", "Hello@World", "Python3"]
for case in test_cases:
result = is_alphanumeric(case)
print(f"{case!r:15} -> {result}")How to Compare Two Strings in Python
Compares two string values and returns a detailed report with equality, case-insensitive comparison, lengths, and uppercase versions.
def compare_data(first_value, second_value):
"""Compare two string values and return a report."""
if first_value == second_value:
status = "MATCH"
else:
status = "DIFFER"
return {
"first_value": first_value,
"second_value": second_value,
"status": status,
…How to Convert Data to Strings in Python
Convert common data types like bytes, numbers, containers, and None to readable strings with a safe helper function.
def to_str(value):
"""Convert common types to a readable string, safe for beginners."""
if isinstance(value, bytes):
return value.decode("utf-8")
if isinstance(value, (dict, list, tuple, set)):
return str(value)
if value is None:
return ""
return str(value)
if __name__ == …How to Detect Expired Domains Using Python
Parse a list of domain registration data and compare expiry dates to today to find expired domains.
import datetime
# List of test domains with fake registration and expiry dates
# Format: (domain, registration_date, expiry_date)
test_domains = [
('example.com', '2020-01-15', '2024-01-15'), # Expired
('google.com', '1997-09-15', '2026-09-15'), # Still active
('test-site.org', '2019-06-01', '2023-06-0…How to Detect PII in Documents Using Python
Use regex patterns to automatically detect emails, phone numbers, SSNs, and credit card numbers in text documents.
import re
from typing import List, Dict
def detect_pii(text: str) -> Dict[str, List[str]]:
patterns = {
"email": r"[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}",
"phone": r"\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}",
"ssn": r"\b\d{3}-\d{2}-\d{4}\b",
"credit_card": r"\b\d{4}[- ]?\d{4}[-…How to Detect if a String Contains Only ASCII in Python
This code defines a function that checks whether every character in a given string is an ASCII character (Unicode code point < 128) and demonstrates it with multiple test cases.
def is_ascii_only(text: str) -> bool:
"""Return True if all characters in text are ASCII, False otherwise."""
return all(ord(char) < 128 for char in text)
if __name__ == "__main__":
# Test cases
samples = [
"Hello, world!",
"Café au lait",
"日本語テキスト",
"ASCII only 123",
…How to Inspect String Statistics in Python
A beginner-friendly function that returns detailed statistics about a string, including length, word count, character types, and easy text transformations.
def inspect_text(text: str) -> dict:
"""Return useful stats about a string for beginners."""
words = text.split()
return {
"length": len(text),
"word_count": len(words),
"uppercase": sum(1 for ch in text if ch.isupper()),
"lowercase": sum(1 for ch in text if ch.islower()),
…How to Join Multiline Text with a Semicolon Separator in Python
This code joins non-empty lines of multiline text into a single string separated by semicolons, stripping leading and trailing whitespace from each line.
def join_multiline_text_with_semicolon(text):
"""Join lines of multiline text with a semicolon separator."""
lines = [line.strip() for line in text.splitlines() if line.strip()]
return "; ".join(lines)
if __name__ == "__main__":
sample_text = """First line
Second line
Third line"""
result = join_…How to Strip Whitespace in Python
This code demonstrates how to remove leading and trailing whitespace from a string using the built-in strip() method.
def strip_whitespace(text: str) -> str:
return text.strip()
if __name__ == "__main__":
sample = " Hello, world! "
result = strip_whitespace(sample)
print(f"Original: '{sample}'")
print(f"Stripped: '{result}'")How to parse key=value pairs in Python
Parse a single line of key=value pairs separated by a delimiter into a Python dictionary.
def parse_key_value_pairs(line: str, delimiter: str = "&") -> dict:
"""Parse a single line of key=value pairs into a dictionary."""
pairs = {}
for token in line.split(delimiter):
if not token.strip():
continue
key, _, value = token.partition("=")
pairs[key.strip()] = val…Python String isalpha() Method: Check if String is Alphabetic
This code defines a function that uses Python's str.isalpha() method to determine if a string contains only alphabetic characters, with a demonstration on several test strings.
def is_alphabetic(s):
return s.isalpha()
if __name__ == "__main__":
test_strings = ["Hello", "Hello123", "World!", "Python", ""]
for s in test_strings:
print(f"{s!r}: {is_alphabetic(s)}")Validate email format with regex in Python
A Python function using a regex pattern to validate simple email formats, returning True or False for each input.
import re
def is_valid_email(email):
pattern = r'^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$'
return bool(re.match(pattern, email))
if __name__ == "__main__":
test_emails = [
"user@example.com",
"first.last@sub.domain.org",
"invalid-email",
"user@.com",
"user@…How to Check if a List is Sorted in Descending Order in Python
This code defines a function that returns True if a given list is sorted in descending order, using a generator expression with all() to compare each adjacent pair.
def is_descending(lst):
"""Return True if list is sorted in descending order."""
return all(lst[i] >= lst[i + 1] for i in range(len(lst) - 1))
if __name__ == "__main__":
test_cases = [
[5, 4, 3, 2, 1],
[3, 3, 2, 1],
[1, 2, 3],
[10, 8, 9],
[]
]
for case in …How to Interleave Two Lists in Python Until One List Exhausted
Interleave elements from two lists pairwise using zip, stopping when either list runs out of items.
def interleave(a, b):
result = []
for x, y in zip(a, b):
result.extend([x, y])
return result
if __name__ == "__main__":
list1 = [1, 2, 3, 4, 5]
list2 = ["a", "b", "c"]
print(interleave(list1, list2))How to Merge Two Sorted Lists in Python
Merge two sorted lists into one sorted list using a two-pointer loop, then extend with remaining elements.
def merge_sorted_lists(list1, list2):
merged = []
i = j = 0
while i < len(list1) and j < len(list2):
if list1[i] <= list2[j]:
merged.append(list1[i])
i += 1
else:
merged.append(list2[j])
j += 1
merged.extend(list1[i:])
merged…How to Safely Convert a List of Strings to Integers in Python
Convert a list of strings to integers while skipping invalid entries and collecting the failed values for inspection.
def safe_to_int(values):
"""Safely convert a list of strings to integers, skipping invalid entries."""
result = []
errors = []
for value in values:
try:
result.append(int(value))
except (ValueError, TypeError):
errors.append(value)
return result, errors
if …How to Truncate a List to Max Length in Python (Keep Head)
This code returns a new list containing only the first max_length items from the original list, using Python's slice syntax.
from typing import List
def truncate_head(lst: List[object], max_length: int) -> List[object]:
"""Return a new list with at most max_length items from the head."""
if max_length < 0:
raise ValueError("max_length must be non-negative")
return lst[:max_length]
if __name__ == "__main__":
# Examp…How to Validate Text Against Forbidden Words in Python
Checks whether a given text contains any forbidden words and returns a tuple with validity and offending words.
def validate_text(text, forbidden_words):
"""
Checks that text does not contain any forbidden words.
Returns (is_valid, offending_words) tuple.
"""
words = text.lower().split()
found = [word for word in words if word in forbidden_words]
return len(found) == 0, found
if __name__ == "__main…How to Zip Two Lists into Pairs in Python
Combine two lists element-wise into a list of tuples using Python's built-in zip() function.
def zip_lists_into_pairs(list1, list2):
pairs = list(zip(list1, list2))
return pairs
if __name__ == "__main__":
fruits = ["apple", "banana", "cherry"]
quantities = [3, 5, 2]
result = zip_lists_into_pairs(fruits, quantities)
print(result)How to unzip a list of pairs into two lists in Python
Split a list of (a, b) tuples into two separate lists by iterating with a for loop and appending each element to its own output list.
def unzip(pairs):
"""Split a list of (a, b) pairs into two separate lists."""
if not pairs:
return [], []
firsts = []
seconds = []
for a, b in pairs:
firsts.append(a)
seconds.append(b)
return firsts, seconds
if __name__ == "__main__":
pairs = [(1, 'a'), (…Pairwise Adjacent Differences in a Python List
Computes the absolute differences between each pair of adjacent elements in a list using a concise list comprehension.
def adjacent_differences(nums):
"""Return list of absolute differences between adjacent elements."""
return [abs(nums[i] - nums[i + 1]) for i in range(len(nums) - 1)]
if __name__ == "__main__":
sample = [3, 7, 2, 9, 5]
diffs = adjacent_differences(sample)
print("Original list:", sample)
print…Browse by section
Each section groups closely related Python snippets.
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.