Comprehensions & generators
List/dict/set comprehensions, generator expressions, and lazy iteration.
Flatten a Nested List in Python (Recursive Generator)
Recursively flatten arbitrarily nested lists into a single-level list using both a function and a generator with `yield from`.
def flatten(nested_list):
"""Recursively flatten a nested list into a single-level list."""
result = []
for item in nested_list:
if isinstance(item, list):
result.extend(flatten(item))
else:
result.append(item)
return result
def flatten_generator(nested_list):
…How to filter a generator with a predicate function in Python
This code defines a generator function that yields only items from an iterable that satisfy a given predicate, then tests it with even and positive number filters.
def filter_gen(predicate, iterable):
for item in iterable:
if predicate(item):
yield item
def is_even(num):
return num % 2 == 0
def is_positive(num):
return num > 0
if __name__ == "__main__":
numbers = range(-5, 10)
even_numbers = list(filter_gen(is_even, numbers))
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Comprehensions & generators — Python code examples
What you will find here
This page collects comprehensions & generators snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
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.