BUG: Fix display with nested NumPy arrays (pydata#10222)

Author: basnijholt

xarray/core/formatting.py

@@ -190,7 +190,7 @@ def format_item(x, timedelta_format=None, quote_strings=True):
         if hasattr(x, "dtype"):
             x = x.item()
         return repr(x) if quote_strings else x
-    elif hasattr(x, "dtype") and np.issubdtype(x.dtype, np.floating):
+    elif hasattr(x, "dtype") and np.issubdtype(x.dtype, np.floating) and x.shape == ():
         return f"{x.item():.4}"
     else:
         return str(x)

xarray/tests/test_formatting.py

@@ -101,6 +101,9 @@ def test_format_item(self) -> None:
             (np.float16(1.1234), "1.123"),
             (np.float32(1.0111111), "1.011"),
             (np.float64(22.222222), "22.22"),
+            (np.zeros((1, 1)), "[[0.]]"),
+            (np.zeros(2), "[0. 0.]"),
+            (np.zeros((2, 2)), "[[0. 0.]\n [0. 0.]]"),
         ]
         for item, expected in cases:
             actual = formatting.format_item(item)

xarray/tests/test_plot.py

@@ -828,7 +828,7 @@ def test_slice_in_title_single_item_array(self) -> None:
         darray = self.darray.expand_dims({"d": np.array([10.009])})
         darray.plot.line(x="period")
         title = plt.gca().get_title()
-        assert "d = 10.01" == title
+        assert "d = [10.009]" == title
 
 
 class TestPlotStep(PlotTestCase):