pass kwargs through from save_mfdataset to to_netcdf

doc/whats-new.rst

@@ -30,6 +30,10 @@ Deprecations
 Bug fixes
 ~~~~~~~~~
 
+- :py:meth:`xarray.save_mfdataset` now passes ``**kwargs`` on to ``to_netcdf``,
+  allowing the ``encoding`` and ``unlimited_dims`` options with ``save_mfdataset``.
+  (:issue:`6684`)
+  By `Travis A. O'Brien <https://github.com/taobrienlbl>`_.
 
 Documentation
 ~~~~~~~~~~~~~

xarray/backends/api.py

@@ -1258,7 +1258,14 @@ def dump_to_store(
 
 
 def save_mfdataset(
-    datasets, paths, mode="w", format=None, groups=None, engine=None, compute=True
+    datasets,
+    paths,
+    mode="w",
+    format=None,
+    groups=None,
+    engine=None,
+    compute=True,
+    **kwargs,
 ):
     """Write multiple datasets to disk as netCDF files simultaneously.
 
@@ -1280,6 +1287,7 @@ def save_mfdataset(
         these locations will be overwritten.
     format : {"NETCDF4", "NETCDF4_CLASSIC", "NETCDF3_64BIT", \
               "NETCDF3_CLASSIC"}, optional
+    **kwargs : additional arguments are passed along to ``to_netcdf``
 
         File format for the resulting netCDF file:
 
@@ -1358,7 +1366,15 @@ def save_mfdataset(
     writers, stores = zip(
         *[
             to_netcdf(
-                ds, path, mode, format, group, engine, compute=compute, multifile=True
+                ds,
+                path,
+                mode,
+                format,
+                group,
+                engine,
+                compute=compute,
+                multifile=True,
+                **kwargs,
             )
             for ds, path, group in zip(datasets, paths, groups)
         ]

xarray/tests/test_backends.py

@@ -3706,6 +3706,29 @@ def test_save_mfdataset_pathlib_roundtrip(self) -> None:
                 ) as actual:
                     assert_identical(actual, original)
 
+    def test_save_mfdataset_pass_kwargs():
+        # create a timeseries to store in a netCDF file
+        times = [0, 1]
+        time = xr.DataArray(times, dims=("time",))
+
+        # create a simple dataset to write using save_mfdataset
+        test_ds = xr.Dataset()
+        test_ds["time"] = time
+
+        # make sure the times are written as double and
+        # turn off fill values
+        encoding = dict(time=dict(dtype="double"))
+        unlimited_dims = ["time"]
+
+        # set the output file name
+        output_path = "test.nc"
+
+        # attempt to write the dataset with the encoding and unlimited args
+        # passed through
+        xr.save_mfdataset(
+            [test_ds], [output_path], encoding=encoding, unlimited_dims=unlimited_dims
+        )
+
     def test_open_and_do_math(self) -> None:
         original = Dataset({"foo": ("x", np.random.randn(10))})
         with create_tmp_file() as tmp: