[Datasets] Improve Covost 2 (#3281)

* [Datasets] Improve Covost 2

* up

* Delete validated.tsv

* Delete covost_v2.en_de.tsv

* finish

Co-authored-by: Quentin Lhoest <42851186+lhoestq@users.noreply.github.com>

datasets/covost2/covost2.py

@@ -87,10 +87,7 @@ class Covost2(datasets.GeneratorBasedBuilder):
 
     @property
     def manual_download_instructions(self):
-        return """\
-        You should download the Common Voice v4 dataset from https://commonvoice.mozilla.org/en/datasets.
-        and unpack it to a path `{COVOST_ROOT}/{SOURCE_LANG_ID}` and then pass the `{COVOST_ROOT}` path as `data_dir`
-        via `datasets.load_dataset('covost2', data_dir="path/to/covost_root")`
+        return f"""Please download the Common Voice Corpus 4 in {self.config.name.split('_')[0]} from https://commonvoice.mozilla.org/en/datasets and unpack it with `tar xvzf {self.config.name.split('_')[0]}.tar`. Make sure to pass the path to the directory in which you unpacked the downloaded file as `data_dir`: `datasets.load_dataset('covost2', data_dir="path/to/dir")`
         """
 
     def _info(self):
@@ -111,29 +108,27 @@ def _info(self):
 
     def _split_generators(self, dl_manager):
         data_root = os.path.abspath(os.path.expanduser(dl_manager.manual_dir))
+
         source_lang, target_lang = self.config.name.split("_")
-        source_path = os.path.join(data_root, source_lang)
 
-        if not os.path.exists(source_path):
+        if not os.path.exists(data_root):
             raise FileNotFoundError(
-                "{} does not exist. Make sure you insert a manual dir via "
-                "`datasets.load_dataset('covost2', data_dir=...)` that includes files uncompressed files from the "
-                "COVOST2 archive. Manual download instructions: {}".format(
-                    data_root, self.manual_download_instructions
-                )
+                f"You are trying to load the {self.config.name} speech translation dataset."
+                f"It is required that you manually download the input speech data {source_lang}."
+                "Manual download instructions: {}".format(data_root, self.manual_download_instructions)
             )
 
         covost_url = COVOST_URL_TEMPLATE.format(src_lang=source_lang, tgt_lang=target_lang)
         extracted_path = dl_manager.download_and_extract(covost_url)
 
         covost_tsv_path = os.path.join(extracted_path, f"covost_v2.{source_lang}_{target_lang}.tsv")
-        cv_tsv_path = os.path.join(source_path, "validated.tsv")
+        cv_tsv_path = os.path.join(data_root, "validated.tsv")
 
         return [
             datasets.SplitGenerator(
                 name=datasets.Split.TRAIN,
                 gen_kwargs={
-                    "source_path": source_path,
+                    "source_path": data_root,
                     "covost_tsv_path": covost_tsv_path,
                     "cv_tsv_path": cv_tsv_path,
                     "split": "train",
@@ -142,7 +137,7 @@ def _split_generators(self, dl_manager):
             datasets.SplitGenerator(
                 name=datasets.Split.VALIDATION,
                 gen_kwargs={
-                    "source_path": source_path,
+                    "source_path": data_root,
                     "covost_tsv_path": covost_tsv_path,
                     "cv_tsv_path": cv_tsv_path,
                     "split": "dev",
@@ -151,7 +146,7 @@ def _split_generators(self, dl_manager):
             datasets.SplitGenerator(
                 name=datasets.Split.TEST,
                 gen_kwargs={
-                    "source_path": source_path,
+                    "source_path": data_root,
                     "covost_tsv_path": covost_tsv_path,
                     "cv_tsv_path": cv_tsv_path,
                     "split": "test",