REF:reproject: Make NaN default float nodata & update integer defaults (

corteva#797)

docs/history.rst

@@ -3,6 +3,7 @@ History
 
 Latest
 ------
+- REF:reproject: Make NaN default float nodata & update integer defaults
 
 0.16.0
 ------

rioxarray/raster_array.py

@@ -47,21 +47,23 @@
 # Based on: https://github.com/OSGeo/gdal/blob/
 # dee861e7c91c2da7ef8ff849947713e4d9bd115c/
 # swig/python/gdal-utils/osgeo_utils/gdal_calc.py#L61
+# And: https://github.com/rasterio/rasterio/blob/
+# 9e643c3f563a679aa5400d9b1a263df97b34f9e0/rasterio/dtypes.py#L99-L112
 _NODATA_DTYPE_MAP = {
     1: 255,  # GDT_Byte
     2: 65535,  # GDT_UInt16
     3: -32768,  # GDT_Int16
-    4: 4294967293,  # GDT_UInt32
-    5: -2147483647,  # GDT_Int32
-    6: 3.402823466e38,  # GDT_Float32
-    7: 1.7976931348623158e308,  # GDT_Float64
+    4: 4294967295,  # GDT_UInt32
+    5: -2147483648,  # GDT_Int32
+    6: numpy.nan,  # GDT_Float32
+    7: numpy.nan,  # GDT_Float64
     8: None,  # GDT_CInt16
     9: None,  # GDT_CInt32
-    10: 3.402823466e38,  # GDT_CFloat32
-    11: 1.7976931348623158e308,  # GDT_CFloat64
-    12: None,  # GDT_Int64
-    13: None,  # GDT_UInt64
-    14: None,  # GDT_Int8
+    10: numpy.nan,  # GDT_CFloat32
+    11: numpy.nan,  # GDT_CFloat64
+    12: 18446744073709551615,  # GDT_UInt64
+    13: -9223372036854775808,  # GDT_Int64
+    14: -128,  # GDT_Int8
 }
 
 

rioxarray/raster_writer.py

@@ -123,7 +123,11 @@ def _ensure_nodata_dtype(original_nodata, new_dtype):
     if numpy.issubdtype(new_dtype, numpy.complexfloating):
         nodata = original_nodata
     else:
-        original_nodata = float(original_nodata)
+        original_nodata = (
+            float(original_nodata)
+            if not numpy.issubdtype(type(original_nodata), numpy.integer)
+            else original_nodata
+        )
         failure_message = (
             f"Unable to convert nodata value ({original_nodata}) to "
             f"new dtype ({new_dtype})."

test/integration/test_integration_rioxarray.py

@@ -2165,6 +2165,35 @@ def test_reproject_transform_missing_shape():
     assert reprojected.rio.transform() == affine
 
 
+@pytest.mark.parametrize(
+    "dtype, expected_nodata",
+    [
+        (numpy.uint8, 255),
+        (numpy.int8, -128),
+        (numpy.uint16, 65535),
+        (numpy.int16, -32768),
+        (numpy.uint32, 4294967295),
+        (numpy.int32, -2147483648),
+        (numpy.float32, numpy.nan),
+        (numpy.float64, numpy.nan),
+        (numpy.complex64, numpy.nan),
+        (numpy.complex128, numpy.nan),
+        (numpy.uint64, 18446744073709551615),
+        (numpy.int64, -9223372036854775808),
+    ],
+)
+def test_reproject_default_nodata(dtype, expected_nodata):
+    test_da = xarray.DataArray(
+        numpy.zeros((5, 5), dtype=dtype),
+        dims=("y", "x"),
+        coords={"y": numpy.arange(1, 6), "x": numpy.arange(2, 7)},
+    ).rio.write_crs("epsg:3857", inplace=True)
+    if numpy.isnan(expected_nodata):
+        assert numpy.isnan(test_da.rio.reproject(4326).rio.nodata)
+    else:
+        assert test_da.rio.reproject(4326).rio.nodata == expected_nodata
+
+
 class CustomCRS:
     @property
     def wkt(self):