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Comprehensions & generators

List/dict/set comprehensions, generator expressions, and lazy iteration.

3 matches

Build a Generator Pipeline in Python: Filter Then Map

Create a lazy data pipeline by chaining generator functions that read, filter, map, and write data step by step.

def read_data():
    return ["a", "bb", "ccc", "dd", "eeeee", "f"]


def filter_short(words):
    return (word for word in words if len(word) >= 2)


def map_to_upper(words):
    return (word.upper() for word in words)


def write_data(words):
    for word in words:
        print(word)


if __name__ == "__main__":
   …

12 0 Open

Comprehensions & generators medium

How to Create a Generator Context Manager in Python with contextlib

Create a custom context manager with the @contextlib.contextmanager decorator to manage resources using a generator function.

contextlib context-manager generator

Python

import contextlib

@contextlib.contextmanager
def temporary_directory():
    """Yield a string and clean up after the block exits."""
    print("Creating temp directory...")
    dir_name = "/tmp/example"
    try:
        yield dir_name
    finally:
        print(f"Removing {dir_name}...")

if __name__ == "__main__":
 …

13 0 Open

Comprehensions & generators medium

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.

generators filtering lazy evaluation

Python

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))
    p…

10 0 Open

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