Add support for MasakhaPOS Dataset

flair/datasets/__init__.py

@@ -173,6 +173,7 @@
     KEYPHRASE_INSPEC,
     KEYPHRASE_SEMEVAL2010,
     KEYPHRASE_SEMEVAL2017,
+    MASAKHA_POS,
     NER_ARABIC_ANER,
     NER_ARABIC_AQMAR,
     NER_BASQUE,
@@ -447,6 +448,7 @@
     "KEYPHRASE_INSPEC",
     "KEYPHRASE_SEMEVAL2010",
     "KEYPHRASE_SEMEVAL2017",
+    "MASAKHA_POS",
     "NER_ARABIC_ANER",
     "NER_ARABIC_AQMAR",
     "NER_BASQUE",

flair/datasets/sequence_labeling.py

@@ -4795,3 +4795,104 @@ def __init__(
             sample_missing_splits=False,
             name="nermud",
         )
+
+
+class MASAKHA_POS(MultiCorpus):
+    def __init__(
+        self,
+        languages: Union[str, List[str]] = "bam",
+        version: str = "v1",
+        base_path: Optional[Union[str, Path]] = None,
+        in_memory: bool = True,
+        **corpusargs,
+    ) -> None:
+        """Initialize the MasakhaPOS corpus available on https://github.com/masakhane-io/masakhane-pos.
+
+        It consists of 20 African languages. Pass a language code or a list of language codes to initialize the corpus
+        with the languages you require. If you pass "all", all languages will be initialized.
+        :version: Specifies version of the dataset. Currently, only "v1" is supported.
+        :param base_path: Default is None, meaning that corpus gets auto-downloaded and loaded. You can override this
+        to point to a different folder but typically this should not be necessary.
+        :param in_memory: If True, keeps dataset in memory giving speedups in training.
+        """
+        base_path = flair.cache_root / "datasets" if not base_path else Path(base_path)
+
+        # if only one language is given
+        if isinstance(languages, str):
+            languages = [languages]
+
+        # column format
+        columns = {0: "text", 1: "pos"}
+
+        # this dataset name
+        dataset_name = self.__class__.__name__.lower()
+
+        supported_versions = ["v1"]
+
+        if version not in supported_versions:
+            log.error(f"The specified version '{version}' is not in the list of supported version!")
+            log.error(f"Supported versions are '{supported_versions}'!")
+            raise Exception
+
+        data_folder = base_path / dataset_name / version
+
+        supported_languages = [
+            "bam",
+            "bbj",
+            "ewe",
+            "fon",
+            "hau",
+            "ibo",
+            "kin",
+            "lug",
+            "mos",
+            "pcm",
+            "nya",
+            "sna",
+            "swa",
+            "twi",
+            "wol",
+            "xho",
+            "yor",
+            "zul",
+        ]
+
+        data_paths = {
+            "v1": "https://raw.githubusercontent.com/masakhane-io/masakhane-pos/main/data",
+        }
+
+        # use all languages if explicitly set to "all"
+        if languages == ["all"]:
+            languages = supported_languages
+
+        corpora: List[Corpus] = []
+        for language in languages:
+            if language not in supported_languages:
+                log.error(f"Language '{language}' is not in list of supported languages!")
+                log.error(f"Supported are '{supported_languages}'!")
+                log.error("Instantiate this Corpus for instance like so 'corpus = MASAKHA_POS(languages='bam')'")
+                raise Exception
+
+            language_folder = data_folder / language
+
+            # download data if necessary
+            data_path = f"{data_paths[version]}/{language}"
+            cached_path(f"{data_path}/dev.txt", language_folder)
+            cached_path(f"{data_path}/test.txt", language_folder)
+            cached_path(f"{data_path}/train.txt", language_folder)
+
+            # initialize comlumncorpus and add it to list
+            log.info(f"Reading data for language {language}@{version}")
+            corp = ColumnCorpus(
+                data_folder=language_folder,
+                column_format=columns,
+                encoding="utf-8",
+                in_memory=in_memory,
+                name=language,
+                **corpusargs,
+            )
+            corpora.append(corp)
+        super().__init__(
+            corpora,
+            name="africa-pos-" + "-".join(languages),
+        )

tests/test_datasets.py

@@ -808,6 +808,70 @@ def test_german_ler_corpus(tasks_base_path):
     assert len(corpus.test) == 6673, "Mismatch in number of sentences for test split"
 
 
+def test_masakha_pos_corpus(tasks_base_path):
+    # This test covers the complete MasakhaPOS dataset.
+    supported_versions = ["v1"]
+
+    supported_languages = {
+        "v1": [
+            "bam",
+            "bbj",
+            "ewe",
+            "fon",
+            "hau",
+            "ibo",
+            "kin",
+            "lug",
+            "mos",
+            "pcm",
+            "nya",
+            "sna",
+            "swa",
+            "twi",
+            "wol",
+            "xho",
+            "yor",
+            "zul",
+        ],
+    }
+
+    africa_pos_stats = {
+        "v1": {
+            "bam": {"train": 775, "dev": 154, "test": 619},
+            "bbj": {"train": 750, "dev": 149, "test": 599},
+            "ewe": {"train": 728, "dev": 145, "test": 582},
+            "fon": {"train": 810, "dev": 161, "test": 646},
+            "hau": {"train": 753, "dev": 150, "test": 601},
+            "ibo": {"train": 803, "dev": 160, "test": 642},
+            "kin": {"train": 757, "dev": 151, "test": 604},
+            "lug": {"train": 733, "dev": 146, "test": 586},
+            "mos": {"train": 757, "dev": 151, "test": 604},
+            "pcm": {"train": 752, "dev": 150, "test": 600},
+            "nya": {"train": 728, "dev": 145, "test": 582},
+            "sna": {"train": 747, "dev": 149, "test": 596},
+            "swa": {"train": 693, "dev": 138, "test": 553},
+            "twi": {"train": 785, "dev": 157, "test": 628},
+            "wol": {"train": 782, "dev": 156, "test": 625},
+            "xho": {"train": 752, "dev": 150, "test": 601},
+            "yor": {"train": 893, "dev": 178, "test": 713},
+            "zul": {"train": 753, "dev": 150, "test": 601},
+        },
+    }
+
+    def check_number_sentences(reference: int, actual: int, split_name: str, language: str, version: str):
+        assert actual == reference, f"Mismatch in number of sentences for {language}@{version}/{split_name}"
+
+    for version in supported_versions:
+        for language in supported_languages[version]:
+            corpus = flair.datasets.MASAKHA_POS(languages=language, version=version)
+
+            gold_stats = africa_pos_stats[version][language]
+
+            check_number_sentences(len(corpus.train), gold_stats["train"], "train", language, version)
+            check_number_sentences(len(corpus.dev), gold_stats["dev"], "dev", language, version)
+            check_number_sentences(len(corpus.test), gold_stats["test"], "test", language, version)
+
+
 def test_multi_file_jsonl_corpus_should_use_label_type(tasks_base_path):
     corpus = MultiFileJsonlCorpus(
         train_files=[tasks_base_path / "jsonl/train.jsonl"],