BUG: Preserve original data type for writing to disk

docs/history.rst

@@ -12,6 +12,7 @@ Latest
 - BUG: Return correct transform in `rio.transform` with non-rectilinear transform (discussions #280)
 - BUG: Update to handle WindowError in rasterio 1.2.2 (issue #286)
 - BUG: Don't generate x,y coords in `rio` methods if not previously there (pull #294)
+- BUG: Preserve original data type for writing to disk (issue #305)
 
 0.3.2
 -----

rioxarray/_io.py

@@ -812,6 +812,8 @@ def open_rasterio(
     encoding = {}
     if mask_and_scale and "_Unsigned" in attrs:
         unsigned = variables.pop_to(attrs, encoding, "_Unsigned") == "true"
+    elif masked:
+        encoding["dtype"] = str(riods.dtypes[0])
 
     da_name = attrs.pop("NETCDF_VARNAME", default_name)
     data = indexing.LazilyOuterIndexedArray(

rioxarray/raster_array.py

@@ -882,6 +882,11 @@ def to_raster(
         if driver is None and LooseVersion(rasterio.__version__) < LooseVersion("1.2"):
             driver = "GTiff"
 
+        dtype = (
+            self._obj.encoding.get("dtype", str(self._obj.dtype))
+            if dtype is None
+            else dtype
+        )
         dtype = str(self._obj.dtype) if dtype is None else dtype
         # get the output profile from the rasterio object
         # if opened with xarray.open_rasterio()

test/integration/test_integration__io.py

@@ -270,7 +270,11 @@ def test_open_rasterio_mask_chunk_clip():
         assert np.isnan(xdi.values).sum() == 52119
         test_encoding = dict(xdi.encoding)
         assert test_encoding.pop("source").endswith("small_dem_3m_merged.tif")
-        assert test_encoding == {"_FillValue": 0.0, "grid_mapping": "spatial_ref"}
+        assert test_encoding == {
+            "_FillValue": 0.0,
+            "grid_mapping": "spatial_ref",
+            "dtype": "uint16",
+        }
         attrs = dict(xdi.attrs)
         assert_almost_equal(
             tuple(xdi.rio._cached_transform())[:6],
@@ -307,7 +311,11 @@ def test_open_rasterio_mask_chunk_clip():
         _assert_xarrays_equal(clipped, comp_subset)
         test_encoding = dict(clipped.encoding)
         assert test_encoding.pop("source").endswith("small_dem_3m_merged.tif")
-        assert test_encoding == {"_FillValue": 0.0, "grid_mapping": "spatial_ref"}
+        assert test_encoding == {
+            "_FillValue": 0.0,
+            "grid_mapping": "spatial_ref",
+            "dtype": "uint16",
+        }
 
         # test dataset
         clipped_ds = xdi.to_dataset(name="test_data").rio.clip(
@@ -317,7 +325,11 @@ def test_open_rasterio_mask_chunk_clip():
         _assert_xarrays_equal(clipped_ds, comp_subset_ds)
         test_encoding = dict(clipped.encoding)
         assert test_encoding.pop("source").endswith("small_dem_3m_merged.tif")
-        assert test_encoding == {"_FillValue": 0.0, "grid_mapping": "spatial_ref"}
+        assert test_encoding == {
+            "_FillValue": 0.0,
+            "grid_mapping": "spatial_ref",
+            "dtype": "uint16",
+        }
 
 
 ##############################################################################
@@ -912,6 +924,7 @@ def test_no_mask_and_scale(open_rasterio):
             "_FillValue": 32767.0,
             "missing_value": 32767,
             "grid_mapping": "crs",
+            "dtype": "uint16",
         }
         attrs = rds.air_temperature.attrs
         assert attrs == {

test/integration/test_integration_rioxarray.py

@@ -1160,6 +1160,7 @@ def test_to_raster(
         assert_array_equal(rds.read(1), xds.fillna(xds.rio.encoded_nodata).values)
         assert rds.count == 1
         assert rds.tags() == {"AREA_OR_POINT": "Area", **test_tags, **xds_attrs}
+        assert rds.dtypes == ("int16",)
 
 
 @pytest.mark.parametrize(