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# Lint as: python3
"""Introduction to MSRA NER Dataset"""

import datasets


logger = datasets.logging.get_logger(__name__)


_CITATION = """\
@inproceedings{levow2006third,
  author    = {Gina{-}Anne Levow},
  title     = {The Third International Chinese Language Processing Bakeoff: Word
               Segmentation and Named Entity Recognition},
  booktitle = {SIGHAN@COLING/ACL},
  pages     = {108--117},
  publisher = {Association for Computational Linguistics},
  year      = {2006}
}
"""

_DESCRIPTION = """\
The Third International Chinese Language
Processing Bakeoff was held in Spring
2006 to assess the state of the art in two
important tasks: word segmentation and
named entity recognition. Twenty-nine
groups submitted result sets in the two
tasks across two tracks and a total of five
corpora. We found strong results in both
tasks as well as continuing challenges.

MSRA NER is one of the provided dataset.
There are three types of NE, PER (person),
ORG (organization) and LOC (location).
The dataset is in the BIO scheme.

For more details see https://faculty.washington.edu/levow/papers/sighan06.pdf
"""

_URL = "https://raw.githubusercontent.com/OYE93/Chinese-NLP-Corpus/master/NER/MSRA/"
_TRAINING_FILE = "msra_train_bio.txt"
_TEST_FILE = "msra_test_bio.txt"


class MsraNerConfig(datasets.BuilderConfig):
    """BuilderConfig for MsraNer"""

    def __init__(self, **kwargs):
        """BuilderConfig for MSRA NER.

        Args:
          **kwargs: keyword arguments forwarded to super.
        """
        super(MsraNerConfig, self).__init__(**kwargs)


class MsraNer(datasets.GeneratorBasedBuilder):
    """MSRA NER dataset."""

    BUILDER_CONFIGS = [
        MsraNerConfig(name="msra_ner", version=datasets.Version("1.0.0"), description="MSRA NER dataset"),
    ]

    def _info(self):
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                {
                    "id": datasets.Value("string"),
                    "tokens": datasets.Sequence(datasets.Value("string")),
                    "ner_tags": datasets.Sequence(
                        datasets.features.ClassLabel(
                            names=[
                                "O",
                                "B-PER",
                                "I-PER",
                                "B-ORG",
                                "I-ORG",
                                "B-LOC",
                                "I-LOC",
                            ]
                        )
                    ),
                }
            ),
            supervised_keys=None,
            homepage="https://www.microsoft.com/en-us/download/details.aspx?id=52531",
            citation=_CITATION,
        )

    def _split_generators(self, dl_manager):
        """Returns SplitGenerators."""
        urls_to_download = {
            "train": f"{_URL}{_TRAINING_FILE}",
            "test": f"{_URL}{_TEST_FILE}",
        }
        downloaded_files = dl_manager.download_and_extract(urls_to_download)

        return [
            datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"filepath": downloaded_files["train"]}),
            datasets.SplitGenerator(name=datasets.Split.TEST, gen_kwargs={"filepath": downloaded_files["test"]}),
        ]

    def _generate_examples(self, filepath):
        logger.info("⏳ Generating examples from = %s", filepath)
        with open(filepath, encoding="utf-8") as f:
            guid = 0
            tokens = []
            ner_tags = []
            for line in f:
                line_stripped = line.strip()
                if line_stripped == "":
                    if tokens:
                        yield guid, {
                            "id": str(guid),
                            "tokens": tokens,
                            "ner_tags": ner_tags,
                        }
                        guid += 1
                        tokens = []
                        ner_tags = []
                else:
                    splits = line_stripped.split("\t")
                    if len(splits) == 1:
                        splits.append("O")
                    tokens.append(splits[0])
                    ner_tags.append(splits[1])
            # last example
            yield guid, {
                "id": str(guid),
                "tokens": tokens,
                "ner_tags": ner_tags,
            }