Merge pull request #5962 from mhvk/ma-getitem-nomask-correction

BUG Ensure masked object arrays can always return single items.

2 files changed, 18 insertions, 0 deletions

diff --git a/numpy/ma/core.py b/numpy/ma/core.py
index 24e18a9d6..703580d27 100644
--- a/numpy/ma/core.py
+++ b/numpy/ma/core.py
@@ -3046,6 +3046,7 @@ class MaskedArray(ndarray):
         # mask of being reshaped if it hasn't been set up properly yet...
         # So it's easier to stick to the current version
         _mask = self._mask
+        # Did we extract a single item?
         if not getattr(dout, 'ndim', False):
             # A record ................
             if isinstance(dout, np.void):
@@ -3057,6 +3058,11 @@ class MaskedArray(ndarray):
             # Just a scalar............
             elif _mask is not nomask and _mask[indx]:
                 return masked
+        elif self.dtype.type is np.object_ and self.dtype is not dout.dtype:
+            # self contains an object array of arrays (yes, that happens).
+            # If masked, turn into a MaskedArray, with everything masked.
+            if _mask is not nomask and _mask[indx]:
+                return MaskedArray(dout, mask=True)
         else:
             # Force dout to MA ........
             dout = dout.view(type(self))
diff --git a/numpy/ma/tests/test_core.py b/numpy/ma/tests/test_core.py
index 9cc784d02..2bf782724 100644
--- a/numpy/ma/tests/test_core.py
+++ b/numpy/ma/tests/test_core.py
@@ -685,6 +685,18 @@ class TestMaskedArray(TestCase):
         finally:
             masked_print_option.set_display(ini_display)
 
+    def test_object_with_array(self):
+        mx1 = masked_array([1.], mask=[True])
+        mx2 = masked_array([1., 2.])
+        mx = masked_array([mx1, mx2], mask=[False, True])
+        assert mx[0] is mx1
+        assert mx[1] is not mx2
+        assert np.all(mx[1].data == mx2.data)
+        assert np.all(mx[1].mask)
+        # check that we return a view.
+        mx[1].data[0] = 0.
+        assert mx2[0] == 0.
+
 
 #------------------------------------------------------------------------------
 class TestMaskedArrayArithmetic(TestCase):