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Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
How to Truncate a String with Ellipsis in Python
A function that shortens text to a maximum length and appends an ellipsis when truncation occurs, handling edge cases.
def truncate_with_ellipsis(text: str, max_length: int) -> str:
"""Truncate text to max_length, appending ellipsis if truncated."""
if len(text) <= max_length:
return text
if max_length <= 3:
return text[:max_length]
return text[: max_length - 3] + "..."
if __name__ == "__main__":
t…How to Pad a List to Length n in Python with a Fill Value
Create a reusable function that pads a Python list to a specified length n by appending a fill value, or truncates it when the list is already longer than n.
def pad_list(lst, n, fill_value=None):
"""
Pad a list to length n using fill_value for missing elements.
If the list is longer than n, it is truncated to length n.
"""
if n <= len(lst):
return lst[:n]
return lst + [fill_value] * (n - len(lst))
if __name__ == "__main__":
# Examples…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…Truncate List Keeping Last N Elements in Python
Return a new list containing only the last N elements from a sequence, handling edge cases like zero or oversized counts.
def truncate(seq, keep_last_n):
"""Return a new list keeping only the last n elements."""
if keep_last_n <= 0:
return []
return list(seq)[-keep_last_n:]
if __name__ == "__main__":
data = [10, 20, 30, 40, 50, 60]
print(truncate(data, 3))
print(truncate(data, 0))
print(truncate(data…How to Truncate Text to a Token Budget in Python
Truncate a string to a maximum token budget for LLM context using the tiktoken library and OpenAI's tokenizer.
import tiktoken
def truncate_to_token_budget(text, max_tokens, model="gpt-3.5-turbo"):
enc = tiktoken.encoding_for_model(model)
tokens = enc.encode(text)
if len(tokens) <= max_tokens:
return text
truncated_tokens = tokens[:max_tokens]
return enc.decode(truncated_tokens)
if __name__ == "__…How to Truncate Lineage Back to a Checkpoint in Python
Walks a linked list of lineage nodes upward to find the nearest checkpoint and returns that node, truncating the lineage.
class LineageNode:
def __init__(self, name, parent=None, checkpoint=None):
self.name = name
self.parent = parent
self.checkpoint = checkpoint
def truncate_at_checkpoint(self):
"""Truncate lineage back to the last checkpoint."""
current = self
while current.check…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.