Update folder_based_builder.py

Author: ArjunJagdale

src/datasets/packaged_modules/folder_based_builder/folder_based_builder.py

@@ -67,7 +67,10 @@ def _info(self):
 
         return datasets.DatasetInfo(features=self.config.features)
 
-    def _split_generators(self, dl_manager):
+    def _available_splits(self) -> Optional[List[str]]:
+        return [str(split) for split in self.config.data_files] if isinstance(self.config.data_files, dict) else None
+
+    def _split_generators(self, dl_manager, splits: Optional[List[str]] = None):
         if not self.config.data_files:
             raise ValueError(f"At least one data file must be specified, but got data_files={self.config.data_files}")
         dl_manager.download_config.extract_on_the_fly = True
@@ -119,7 +122,8 @@ def analyze(files_or_archives, downloaded_files_or_dirs, split):
                                 f"The file '{original_file_name}' from the archive '{archive_file_name}' was ignored: it is not a {self.BASE_COLUMN_NAME}, and is not {metadata_filenames} either."
                             )
 
-        data_files = self.config.data_files
+        if splits and isinstance(data_files, dict):
+            data_files = {split: data_files[split] for split in splits}
         splits = []
         for split_name, files in data_files.items():
             if isinstance(files, str):