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Comprehensions & generators

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

3 matches

Batch Rows in Chunks with a Generator in Python

Group a list of row dicts into fixed-size chunks using a generator that yields one slice per call.

from typing import Iterator, List


def batch_rows(rows: List[dict], batch_size: int) -> Iterator[List[dict]]:
    for i in range(0, len(rows), batch_size):
        yield rows[i:i + batch_size]


if __name__ == "__main__":
    sample_rows = [
        {"id": 1, "name": "Alice"},
        {"id": 2, "name": "Bob"},
      …

15 0 Open

Comprehensions & generators easy

Convert Data in Python with Comprehensions and Generators

Convert mixed data to integers, filter and transform numbers, and extract fields from dicts using list comprehensions and generator expressions.

comprehensions generators list-comprehension

Python

def convert_numbers(data):
    """Convert a list of mixed values into integers using a comprehension."""
    return [int(item) for item in data if item is not None]


def double_even_numbers(numbers):
    """Double only even numbers using a generator expression."""
    return (n * 2 for n in numbers if n % 2 == 0)


d…

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Comprehensions & generators easy

How to Parse CSV Rows as Generator Dicts in Python

Reads a CSV file and yields each row as a dictionary one at a time using a generator, so the file is processed lazily.

csv generator parsing

Python

import csv
from pathlib import Path

def csv_to_dicts(filepath):
    with open(filepath, mode="r", newline="", encoding="utf-8") as file:
        reader = csv.DictReader(file)
        for row in reader:
            yield row

if __name__ == "__main__":
    sample_csv = Path("sample_data.csv")
    sample_csv.write_text…

13 0 Open

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