sample_jsonl_first_n.py

#!/usr/bin/env python3
import argparse
from pathlib import Path


def main() -> None:
    parser = argparse.ArgumentParser(description="Write the first N non-empty JSONL lines to a new file.")
    parser.add_argument("--input", required=True, help="Input JSONL file.")
    parser.add_argument("--output", required=True, help="Output JSONL file.")
    parser.add_argument("--limit", type=int, default=100000, help="Number of non-empty lines to keep.")
    args = parser.parse_args()

    input_path = Path(args.input).resolve()
    output_path = Path(args.output).resolve()
    output_path.parent.mkdir(parents=True, exist_ok=True)

    kept = 0
    with input_path.open("r", encoding="utf-8") as src, output_path.open("w", encoding="utf-8") as dst:
        for line in src:
            if not line.strip():
                continue
            dst.write(line)
            kept += 1
            if kept >= args.limit:
                break

    print(f"Wrote {kept} lines to {output_path}")


if __name__ == "__main__":
    main()