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Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
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 Center Text in a Fixed-Width Banner in Python
Centers any text inside a fixed-width banner using fill characters and computed padding.
def center_text_banner(text, width=40, fill_char="="):
"""Center text within a fixed-width banner."""
if len(text) >= width:
return text
total_padding = width - len(text)
left_padding = total_padding // 2
right_padding = total_padding - left_padding
banner_line = fill_char * w…How to Check and Manipulate Strings in Python
Demonstrates core string inspection and transformation methods like case conversion, trimming, splitting, and membership checks on a sample string.
text = " Hello, Python Learners! "
print(f"Original: '{text}'")
print(f"Lowercase: '{text.lower()}'")
print(f"Uppercase: '{text.upper()}'")
print(f"Title case: '{text.title()}'")
print(f"Stripped: '{text.strip()}'")
print(f"Length: {len(text)}")
print(f"Replace: '{text.replace('Python', 'Programming')}'")
print(f"S…How to Convert camelCase to snake_case in Python
Convert camelCase strings to snake_case using a simple Python function that inserts underscores before uppercase letters and lowercases everything.
def camel_to_snake(s):
result = ""
for i, char in enumerate(s):
if char.isupper() and i > 0:
result += "_"
result += char.lower()
return result
if __name__ == "__main__":
test_cases = ["camelCase", "helloWorld", "thisIsACoolExample", "already_snake", "UPPER"]
for case i…How to Convert snake_case to Title Case in Python
Convert snake_case strings to title case by splitting on underscores, capitalizing each word, and joining them with spaces.
def to_title_case(snake_str):
words = snake_str.split("_")
return " ".join(word.capitalize() for word in words)
if __name__ == "__main__":
examples = ["hello_world", "convert_snake_case", "already_title_case", "multiple__under_scores"]
for example in examples:
print(f"{example!r:35} -> {to_tit…How to Format Strings with Named Placeholders in Python
Format a template string using named placeholders with the str.format() method and a dictionary.
def format_named(template, data):
"""Format a template string using named placeholders."""
return template.format(**data)
if __name__ == "__main__":
template = "Hello {name}, you are {age} years old and live in {city}."
data = {"name": "Alice", "age": 30, "city": "London"}
result = format_named(t…How to Format Text in Python
A beginner-friendly helper that cleans and changes the case of a string, with options for title, upper, lower, and capitalize.
def format_text(text, case="title", strip_whitespace=True, remove_extra_spaces=True):
"""
Formats a string based on common beginner needs.
Args:
text: Input string to format
case: "title", "upper", "lower", or "capitalize"
strip_whitespace: Remove leading/trailing whitespace
…How to Format Text in Python (Beginner's Guide)
This beginner-friendly Python script demonstrates text formatting basics: stripping whitespace, converting to title case, replacing substrings, splitting into words, and generating a snippet.
text = " hello world, welcome to python skillset! "
cleaned = text.strip()
title_cased = cleaned.title()
replaced = title_cased.replace("Python", "PYTHON")
words = replaced.split()
word_count = len(words)
first_three = " ".join(words[:3])
snippet = first_three + "..."
print("Original:", repr(text))
print("Stripped:"…How to Format a Float as Currency in Python
This code defines a function that converts a float to a string formatted as US currency with two decimal places and comma separators.
def format_currency(amount):
return f"${amount:,.2f}"
if __name__ == "__main__":
test_amounts = [1234.5, 0, 9999999.999, -42.867]
for amount in test_amounts:
print(f"{amount} -> {format_currency(amount)}")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 Pad a String with Zeros in Python
Pad a string to a fixed width by left-filling it with zeros using the built-in str.zfill method.
def pad_zeros(s, width):
return s.zfill(width)
if __name__ == "__main__":
print(repr(pad_zeros("42", 6)))
print(repr(pad_zeros("-7", 5)))
print(repr(pad_zeros("hello", 10)))
print(repr(pad_zeros("123", 3)))How to Round Numbers with f-strings in Python
Round numbers directly inside f-string expressions using the built-in round() function for clean, readable output formatting.
def main():
# Values to format with expression-based rounding
price = 19.995
tax_rate = 0.0825
distance = 1234.56789
# Round inside the f-string expression using round()
print(f"Price rounded to cents: ${round(price, 2)}")
# Combine rounding with arithmetic inside the expression
total…How to Transform Text in Python with a Helper Function
Build a simple Python helper to strip extra whitespace and convert text to upper, lower, or title case.
def transform_text(text, upper=False, lower=False, strip_whitespace=False, title_case=False):
"""Apply common string transformations for beginners."""
result = text
if strip_whitespace:
result = " ".join(result.split())
if upper and lower:
raise ValueError("Cannot apply both upper and…How to wrap long text to a specified width in Python
Uses Python's textwrap.fill to wrap a long string to a specified width at word boundaries, preserving readability in console output or logs.
import textwrap
text = """This is a long piece of text that definitely exceeds the width limit
if we try to print it on a single line without any wrapping applied."""
wrapped = textwrap.fill(text, width=40)
print(wrapped)Validate email format with regex in Python
A Python function using a regex pattern to validate simple email formats, returning True or False for each input.
import re
def is_valid_email(email):
pattern = r'^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$'
return bool(re.match(pattern, email))
if __name__ == "__main__":
test_emails = [
"user@example.com",
"first.last@sub.domain.org",
"invalid-email",
"user@.com",
"user@…Format Lists of Tuples into Numbered Lines in Python
This code loops through a list of (name, grade) tuples and formats each into a numbered line using enumerate and f-strings.
def format_students(students):
formatted = []
for i, student in enumerate(students, start=1):
name, grade = student
formatted.append(f"{i}. {name}: {grade}")
return "\n".join(formatted)
if __name__ == "__main__":
students = [
("Alice", 92),
("Bob", 85),
("Charl…How to check list items by type and emptiness in Python
Loop through a list with enumerate(), classify each item as empty, number, or text, and print a formatted status for each element.
def check_data(data):
"""Check each item in a list and print whether it's valid."""
for i, item in enumerate(data):
if item is None or item == "":
status = "empty"
elif isinstance(item, (int, float)):
status = "number"
else:
status = "text"
pr…Replace Negative Values in a List with Python
This code defines a function that replaces every negative number in a list with a replacement value, defaulting to zero, using a list comprehension.
def replace_if_negative(values, replacement=0):
return [replacement if value < 0 else value for value in values]
if __name__ == "__main__":
numbers = [5, -3, 8, -1, 0, -7, 2]
result = replace_if_negative(numbers)
print(f"Original: {numbers}")
print(f"Replaced: {result}")Format CLI help text in Python
Build a readable usage string for a command-line tool, aligning flags and wrapping descriptions with the textwrap module.
import textwrap
def format_help(command_name: str, description: str, options: list[tuple[str, str]]) -> str:
"""Format CLI help text into a readable usage string."""
header = f"Usage: {command_name} [OPTIONS]"
lines = [header, "", description, "", "Options:"]
for flag, help_text in options:
…How to Print Colored Text in Python with ANSI Codes
Define a small Colors class and a colored() helper to print styled terminal text using ANSI escape codes.
class Colors:
RESET = "\033[0m"
RED = "\033[31m"
GREEN = "\033[32m"
YELLOW = "\033[33m"
BLUE = "\033[34m"
MAGENTA = "\033[35m"
CYAN = "\033[36m"
WHITE = "\033[37m"
BOLD = "\033[1m"
UNDERLINE = "\033[4m"
def colored(text, color):
return f"{color}{text}{Colors.RESET}"
if _…How to Assert an Invariant After a Complex Transformation in Python
Use assert to verify that a multi-step transformation preserves a mathematical invariant, catching regressions early.
def transform_value(value):
"""Apply several transformations to a value."""
doubled = value * 2
shifted = doubled + 10
normalized = shifted / 2
return int(normalized)
def assert_invariant(value):
"""Assert that the transformation preserves a key invariant."""
original = value
transform…How to Log Exceptions with traceback.format_exc in Python
Capture and log a full traceback string when an exception occurs using Python's traceback.format_exc() and logging module.
import traceback
import logging
def risky_operation(value):
return 10 / value
logging.basicConfig(level=logging.ERROR, format='%(asctime)s - %(levelname)s - %(message)s')
def main():
try:
result = risky_operation(0)
print(f"Result: {result}")
except ZeroDivisionError:
error_msg =…How to Raise a Custom Exception with Extra Context in Python
Define a custom exception that carries extra context fields and raise it to provide richer error information.
class InsufficientFundsError(Exception):
def __init__(self, balance, amount):
self.balance = balance
self.amount = amount
super().__init__(f"Withdrawal of ${amount} failed: balance ${balance} is insufficient")
def withdraw(balance, amount):
if amount > balance:
raise Insuffici…Log to stderr with Python logging basicConfig
Configure Python's logging module to send all log messages to standard error (stderr) instead of the default stderr, with a readable timestamped format.
import logging
def main():
logging.basicConfig(
level=logging.DEBUG,
format="%(asctime)s — %(name)s — %(levelname)s — %(message)s",
stream=__import__("sys").stderr,
)
logger = logging.getLogger("example")
logger.debug("Debug message")
logger.info("Info message")
logger.…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.