Use compute instead of load in plot (#9818)

* Only compute this array, load computes in place

* Add test

* Update whats-new.rst

* Update whats-new.rst

Author: Illviljan

doc/whats-new.rst

@@ -36,7 +36,8 @@ Deprecations
 
 Bug fixes
 ~~~~~~~~~
-
+- Fix unintended load on datasets when calling :py:meth:`DataArray.plot.scatter` (:pull:`9818`).
+  By `Jimmy Westling <https://github.com/illviljan>`_.
 
 Documentation
 ~~~~~~~~~~~~~

xarray/plot/dataarray_plot.py

@@ -946,7 +946,7 @@ def newplotfunc(
             # Remove any nulls, .where(m, drop=True) doesn't work when m is
             # a dask array, so load the array to memory.
             # It will have to be loaded to memory at some point anyway:
-            darray = darray.load()
+            darray = darray.compute()
             darray = darray.where(darray.notnull(), drop=True)
         else:
             size_ = kwargs.pop("_size", linewidth)

xarray/tests/test_plot.py

@@ -33,6 +33,7 @@
     assert_no_warnings,
     requires_cartopy,
     requires_cftime,
+    requires_dask,
     requires_matplotlib,
     requires_seaborn,
 )
@@ -3326,6 +3327,24 @@ def test_datarray_scatter(
         )
 
 
+@requires_dask
+@requires_matplotlib
+@pytest.mark.parametrize(
+    "plotfunc",
+    ["scatter"],
+)
+def test_dataarray_not_loading_inplace(plotfunc: str) -> None:
+    ds = xr.tutorial.scatter_example_dataset()
+    ds = ds.chunk()
+
+    with figure_context():
+        getattr(ds.A.plot, plotfunc)(x="x")
+
+    from dask.array import Array
+
+    assert isinstance(ds.A.data, Array)
+
+
 @requires_matplotlib
 def test_assert_valid_xy() -> None:
     ds = xr.tutorial.scatter_example_dataset()