Expose is_seg_dataset argument in sam dataset (#736)

Expose is_seg_dataset argument in sam dataset

micro_sam/training/training.py

@@ -389,6 +389,7 @@ def default_sam_dataset(
     is_train: bool = True,
     min_size: int = 25,
     max_sampling_attempts: Optional[int] = None,
+    is_seg_dataset: Optional[bool] = None,
     **kwargs,
 ) -> Dataset:
     """Create a PyTorch Dataset for training a SAM model.
@@ -412,6 +413,8 @@ def default_sam_dataset(
         is_train: Whether this dataset is used for training or validation.
         min_size: Minimal object size. Smaller objects will be filtered.
         max_sampling_attempts: Number of sampling attempts to make from a dataset.
+        is_seg_dataset: Whether the dataset is built 'from torch_em.data import SegmentationDataset'
+            or 'from torch_em.data import ImageCollectionDataset'
 
     Returns:
         The dataset.
@@ -443,8 +446,8 @@ def default_sam_dataset(
     # Set a minimum number of samples per epoch.
     if n_samples is None:
         loader = torch_em.default_segmentation_loader(
-            raw_paths, raw_key, label_paths, label_key,
-            batch_size=1, patch_shape=patch_shape, ndim=2
+            raw_paths, raw_key, label_paths, label_key, batch_size=1,
+            patch_shape=patch_shape, ndim=2, is_seg_dataset=is_seg_dataset,
         )
         n_samples = max(len(loader), 100 if is_train else 5)
 
@@ -454,6 +457,7 @@ def default_sam_dataset(
         raw_transform=raw_transform, label_transform=label_transform,
         with_channels=with_channels, ndim=2,
         sampler=sampler, n_samples=n_samples,
+        is_seg_dataset=is_seg_dataset,
         **kwargs,
     )