src/align_corpora.py

import json
import warnings
from dataclasses import dataclass
from itertools import chain
from pathlib import Path
from typing import Iterable, Optional

from lxml import etree
from tqdm import tqdm


@dataclass
class Document:
    id: str
    subtitles: dict[str, str]

    @classmethod
    def parse_from_file(cls, path: Path):
        tree = etree.parse(str(path))
        root = tree.getroot()
        id = root.get("id")
        subtitles = dict()
        for sub in root:
            if sub.tag == "s":
                content = etree.ElementTree(sub).xpath("string()")
                subtitles[sub.get("id")] = content
        return cls(id, subtitles)


@dataclass
class Link:
    link_id: str
    src: list[str]
    dest: list[str]
    overlap: Optional[float]

    @classmethod
    def from_attributes(cls, attributes: dict[str, str]):
        link_id = attributes["id"]
        src_str, dest_str = attributes["xtargets"].split(";")
        src = [entry_id for entry_id in src_str.split()]
        dest = [entry_id for entry_id in dest_str.split()]
        overlap = attributes.get("overlap")
        if isinstance(overlap, str):
            overlap = float(overlap)
        return cls(link_id, src, dest, overlap)


@dataclass
class LinkGroup:
    src_file: Path
    dest_file: Path
    links: list[Link]

    @classmethod
    def from_element(cls, element: etree.Element, corpus_dir: Path):
        src_file = corpus_dir.joinpath(
            element.attrib["fromDoc"].removesuffix(".gz")
        )
        dest_file = corpus_dir.joinpath(
            element.attrib["toDoc"].removesuffix(".gz")
        )
        links = []
        for sub in element:
            if sub.tag == "link":
                links.append(Link.from_attributes(sub.attrib))
        return cls(src_file, dest_file, links)

    def generate_entries(
        self, src_lang: str, dest_lang: str
    ) -> Iterable[dict]:
        try:
            src_document = Document.parse_from_file(self.src_file)
            dest_document = Document.parse_from_file(self.dest_file)
        except etree.XMLSyntaxError:
            warnings.warn(
                "Could not generate entries for link group, corrupted files."
            )
            return iter([])
        for link in self.links:
            src_str = " ".join(
                [src_document.subtitles[s_id] for s_id in link.src]
            )
            dest_str = " ".join(
                [dest_document.subtitles[s_id] for s_id in link.dest]
            )
            yield {
                "link_id": link.link_id,
                src_lang: src_str,
                dest_lang: dest_str,
                "overlap": link.overlap,
            }


def parse_alignment(path: Path, corpus_dir: Path) -> Iterable[LinkGroup]:
    tree = etree.parse(path)
    for element in tree.getroot():
        if element.tag == "linkGrp" and element.get("targType") == "s":
            yield LinkGroup.from_element(element, corpus_dir)


def iterlen(iterable: Iterable) -> int:
    n = 0
    for _ in iterable:
        n += 1
    return n


def main():
    alignment_file = Path("raw/da-sv.xml")
    corpus_dir = Path("raw/OpenSubtitles/raw/")
    groups = parse_alignment(alignment_file, corpus_dir)
    print("Counting groups...")
    n_groups = iterlen(groups)
    groups = parse_alignment(alignment_file, corpus_dir)
    groups = tqdm(groups, desc="Extracting all alignments...", total=n_groups)
    entries = chain.from_iterable(
        (group.generate_entries("da", "sv") for group in groups)
    )
    out_path = "aligned.jsonl"
    with open(out_path, "w") as out_file:
        for entry in entries:
            out_file.write(json.dumps(entry) + "\n")
    print("Done")


if __name__ == "__main__":
    main()