From 4aa7622b6ff16647df64fe69f39438b7cbe9576c Mon Sep 17 00:00:00 2001
From: darikg <darikg@users.noreply.github.com>
Date: Thu, 27 Aug 2020 10:56:48 -0400
Subject: [PATCH] Use deepcopy recursively on numpy arrays (#4379)

Closes #4362
---
 xarray/core/variable.py        | 15 +++++++--------
 xarray/tests/test_dataarray.py |  6 ++++++
 xarray/tests/test_dataset.py   |  6 ++++++
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/xarray/core/variable.py b/xarray/core/variable.py
index 7c398066830..39d663410ec 100644
--- a/xarray/core/variable.py
+++ b/xarray/core/variable.py
@@ -932,14 +932,13 @@ def copy(self, deep=True, data=None):
                 # don't share caching between copies
                 data = indexing.MemoryCachedArray(data.array)
 
-            if deep:
-                if hasattr(data, "__array_function__") or isinstance(
-                    data, dask_array_type
-                ):
-                    data = data.copy()
-                elif not isinstance(data, PandasIndexAdapter):
-                    # pandas.Index is immutable
-                    data = np.array(data)
+            if deep and (
+                hasattr(data, "__array_function__")
+                or isinstance(data, dask_array_type)
+                or (not IS_NEP18_ACTIVE and isinstance(data, np.ndarray))
+            ):
+                data = copy.deepcopy(data)
+
         else:
             data = as_compatible_data(data)
             if self.shape != data.shape:
diff --git a/xarray/tests/test_dataarray.py b/xarray/tests/test_dataarray.py
index 842b8962352..9c08ad5d8fd 100644
--- a/xarray/tests/test_dataarray.py
+++ b/xarray/tests/test_dataarray.py
@@ -6833,3 +6833,9 @@ def test_delete_coords():
     assert a1.dims == ("y", "x")
     assert set(a0.coords.keys()) == {"x", "y"}
     assert set(a1.coords.keys()) == {"x"}
+
+
+def test_deepcopy_obj_array():
+    x0 = DataArray(np.array([object()]))
+    x1 = deepcopy(x0)
+    assert x0.values[0] is not x1.values[0]
diff --git a/xarray/tests/test_dataset.py b/xarray/tests/test_dataset.py
index 9ac3af90a17..2d37dc670b6 100644
--- a/xarray/tests/test_dataset.py
+++ b/xarray/tests/test_dataset.py
@@ -6454,3 +6454,9 @@ def test_weakref():
     ds = Dataset()
     r = ref(ds)
     assert r() is ds
+
+
+def test_deepcopy_obj_array():
+    x0 = Dataset(dict(foo=DataArray(np.array([object()]))))
+    x1 = deepcopy(x0)
+    assert x0["foo"].values[0] is not x1["foo"].values[0]