Fix to xr dataset merge error with conflicting values in coordinate

satpy/scene.py

@@ -1,4 +1,4 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 # Copyright (c) 2010-2022 Satpy developers
 #
@@ -1076,12 +1076,16 @@
 
 
 
-    def to_xarray_dataset(self, datasets=None):
+    def to_xarray_dataset(self, datasets=None, compat="minimal"):
         """Merge all xr.DataArrays of a scene to a xr.DataSet.
 
         Parameters:
             datasets (list):
                 List of products to include in the :class:`xarray.Dataset`
+            compat (str):
+                How to compare variables with the same name for conflicts.
+                See :func:`xarray.merge` for possible options. Defaults to
+                "minimal" which drops conflicting variables.
 
         Returns: :class:`xarray.Dataset`
 
@@ -1097,7 +1101,7 @@
         mdata = combine_metadata(*tuple(i.attrs for i in dataarrays))
         if mdata.get("area") is None or not isinstance(mdata["area"], SwathDefinition):
             # either don't know what the area is or we have an AreaDefinition
-            ds = xr.merge(ds_dict.values())
+            ds = xr.merge(ds_dict.values(), compat=compat)
         else:
             # we have a swath definition and should use lon/lat values
             lons, lats = mdata["area"].get_lonlats()

satpy/tests/scene_tests/test_conversions.py

@@ -17,7 +17,9 @@
 """Unit tests for Scene conversion functionality."""
 
 import datetime as dt
+from datetime import datetime
 
+import numpy as np
 import pytest
 import xarray as xr
 from dask import array as da
@@ -47,14 +49,6 @@
 class TestSceneConversions:
     """Test Scene conversion to geoviews, xarray, etc."""
 
-    def test_to_xarray_dataset_with_empty_scene(self):
-        """Test converting empty Scene to xarray dataset."""
-        scn = Scene()
-        xrds = scn.to_xarray_dataset()
-        assert isinstance(xrds, xr.Dataset)
-        assert len(xrds.variables) == 0
-        assert len(xrds.coords) == 0
-
     def test_geoviews_basic_with_area(self):
         """Test converting a Scene to geoviews with an AreaDefinition."""
         from pyresample.geometry import AreaDefinition
@@ -157,6 +151,42 @@
         scn["var1"] = data_array
         return scn
 
+    def test_to_xarray_dataset_with_conflicting_variables(self):
+        """Test converting Scene with DataArrays with conflicting variables.
+
+        E.g. "acq_time" in the seviri_l1b_nc reader
+        """
+        from pyresample.geometry import AreaDefinition
+        area = AreaDefinition("test", "test", "test",
+                              {"proj": "geos", "lon_0": -95.5, "h": 35786023.0},
+                              2, 2, [-200, -200, 200, 200])
+        scn = Scene()
+
+        acq_time_1 = ("y", [np.datetime64("1958-01-02 00:00:01"),
+                            np.datetime64("1958-01-02 00:00:02")])
+        ds = xr.DataArray(da.zeros((2, 2), chunks=-1), dims=("y", "x"),
+                attrs={"start_time": datetime(2018, 1, 1), "area": area})
+        ds["acq_time"] = acq_time_1
+
+        scn["ds1"] = ds
+
+        acq_time_2 = ("y", [np.datetime64("1958-02-02 00:00:01"),
+                            np.datetime64("1958-02-02 00:00:02")])
+        ds2 = ds.copy()
+        ds2["acq_time"] = acq_time_2
+
+        scn["ds2"] = ds2
+
+        # drop case (compat="minimal")
+        xrds = scn.to_xarray_dataset()
+        assert isinstance(xrds, xr.Dataset)
+        assert "acq_time" not in xrds.coords
+
+        xrds = scn.to_xarray_dataset(compat="override")
+        assert isinstance(xrds, xr.Dataset)
+        assert "acq_time" in xrds.coords
+        xr.testing.assert_equal(xrds["acq_time"], ds2["acq_time"])
+
     @pytest.fixture()
     def multi_area_scn(self):
         """Define Scene with multiple area."""
@@ -210,6 +240,6 @@
 
     def test_to_xarray_with_multiple_area_scene(self, multi_area_scn):
         """Test converting muiltple area Scene to xarray."""
         # TODO: in future adapt for DataTree implementation
         with pytest.raises(ValueError, match="Datasets to be saved .* must have identical projection coordinates."):
             _ = multi_area_scn.to_xarray()