Fix bug caused by dl_manager returning list instead of str

oe_dataset.py

@@ -25,7 +25,7 @@ else:
 
 from typing import Optional, IO
 
-import datasets
+import datasets, itertools
 
 
 # ---- Constants ----
@@ -121,20 +121,26 @@ class OEDataset(datasets.GeneratorBasedBuilder):
 
         train_masks_paths = dl_manager.download(self.config._masks_urls["train"])
         val_masks_paths = dl_manager.download(self.config._masks_urls["val"])
+
+        train_imgs_gen = itertools.chain.from_iterable([dl_manager.iter_archive(path) for path in train_imgs_paths])
+        val_imgs_gen = itertools.chain.from_iterable([dl_manager.iter_archive(path) for path in val_imgs_paths])
+
+        train_masks_gen = itertools.chain.from_iterable([dl_manager.iter_archive(path) for path in train_masks_paths])
+        val_masks_gen = itertools.chain.from_iterable([dl_manager.iter_archive(path) for path in val_masks_paths])
         
         return [
             datasets.SplitGenerator(
                 name=datasets.Split.TRAIN,
                 gen_kwargs={
-                    "images": dl_manager.iter_archive(train_imgs_paths),
-                    "masks": dl_manager.iter_archive(train_masks_paths),
+                    "images": train_imgs_gen,
+                    "masks": train_masks_gen,
                 },
             ),
             datasets.SplitGenerator(
                 name=datasets.Split.VALIDATION,
                 gen_kwargs={
-                    "images": dl_manager.iter_archive(val_imgs_paths),
-                    "masks": dl_manager.iter_archive(val_masks_paths),
+                    "images": val_imgs_gen,
+                    "masks": val_masks_gen,
                 },
             ),
         ]