Add dtype field to RasterDataset (#1149)

* Adding dtype to RasterDataset

* Removing explicit cast to float for images

* Updating test case

* Reverting

* Compromising on a UserWarning

* Update torchgeo/datasets/geo.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* Adding test

* Changing back

* Set the docstring of dtype

* Good grief

* pydocstyle workaround

* REquested changes

---------

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

torchgeo/datasets/geo.py

@@ -296,6 +296,20 @@ class RasterDataset(GeoDataset):
     #: Color map for the dataset, used for plotting
     cmap: dict[int, tuple[int, int, int, int]] = {}
 
+    @property
+    def dtype(self) -> torch.dtype:
+        """The dtype of the dataset (overrides the dtype of the data file via a cast).
+
+        Returns:
+            the dtype of the dataset
+
+        .. versionadded:: 5.0
+        """
+        if self.is_image:
+            return torch.float32
+        else:
+            return torch.long
+
     def __init__(
         self,
         root: str = "data",
@@ -429,10 +443,12 @@ def __getitem__(self, query: BoundingBox) -> dict[str, Any]:
             data = self._merge_files(filepaths, query, self.band_indexes)
 
         sample = {"crs": self.crs, "bbox": query}
+
+        data = data.to(self.dtype)
         if self.is_image:
-            sample["image"] = data.float()
+            sample["image"] = data
         else:
-            sample["mask"] = data.long()
+            sample["mask"] = data
 
         if self.transforms is not None:
             sample = self.transforms(sample)