Merge pull request #9322 from eric-wieser/ma-astype

BUG: np.ma.astype fails on structured types

2 files changed, 12 insertions, 7 deletions

diff --git a/numpy/ma/core.py b/numpy/ma/core.py
index c2b10d5f8..ab4364706 100644
--- a/numpy/ma/core.py
+++ b/numpy/ma/core.py
@@ -3152,16 +3152,16 @@ class MaskedArray(ndarray):
 
         """
         newtype = np.dtype(newtype)
+        newmasktype = make_mask_descr(newtype)
+
         output = self._data.astype(newtype).view(type(self))
         output._update_from(self)
-        names = output.dtype.names
-        if names is None:
-            output._mask = self._mask.astype(bool)
+
+        if self._mask is nomask:
+            output._mask = nomask
         else:
-            if self._mask is nomask:
-                output._mask = nomask
-            else:
-                output._mask = self._mask.astype([(n, bool) for n in names])
+            output._mask = self._mask.astype(newmasktype)
+
         # Don't check _fill_value if it's None, that'll speed things up
         if self._fill_value is not None:
             output._fill_value = _check_fill_value(self._fill_value, newtype)
diff --git a/numpy/ma/tests/test_core.py b/numpy/ma/tests/test_core.py
index 816e149a9..707fcd1de 100644
--- a/numpy/ma/tests/test_core.py
+++ b/numpy/ma/tests/test_core.py
@@ -4788,6 +4788,11 @@ def test_ufunc_with_output():
     y = np.add(x, 1., out=x)
     assert_(y is x)
 
+def test_astype():
+    descr = [('v', int, 3), ('x', [('y', float)])]
+    x = array(([1, 2, 3], (1.0,)), dtype=descr)
+    assert_equal(x, x.astype(descr))
+
 
 ###############################################################################
 if __name__ == "__main__":