Merge pull request #4843 from juliantaylor/subclass-writeable

BUG: retain writeable flag when indexing subclasses

2 files changed, 17 insertions, 0 deletions

diff --git a/numpy/core/src/multiarray/mapping.c b/numpy/core/src/multiarray/mapping.c
index bf4851519..20488fb85 100644
--- a/numpy/core/src/multiarray/mapping.c
+++ b/numpy/core/src/multiarray/mapping.c
@@ -1058,6 +1058,9 @@ array_boolean_subscript(PyArrayObject *self,
             Py_DECREF(ret);
             return NULL;
         }
+        if (_IsWriteable(ret)) {
+            PyArray_ENABLEFLAGS(ret, NPY_ARRAY_WRITEABLE);
+        }
     }
 
     return ret;
@@ -1583,6 +1586,9 @@ array_subscript(PyArrayObject *self, PyObject *op)
             result = NULL;
             goto finish;
         }
+        if (_IsWriteable(result)) {
+            PyArray_ENABLEFLAGS(result, NPY_ARRAY_WRITEABLE);
+        }
     }
 
   finish:
diff --git a/numpy/core/tests/test_indexing.py b/numpy/core/tests/test_indexing.py
index 44928b264..2dfaf6f3c 100644
--- a/numpy/core/tests/test_indexing.py
+++ b/numpy/core/tests/test_indexing.py
@@ -285,6 +285,17 @@ class TestIndexing(TestCase):
         assert_((a == 1).all())
 
 
+    def test_subclass_writeable(self):
+        d = np.rec.array([('NGC1001', 11), ('NGC1002', 1.), ('NGC1003', 1.)],
+                         dtype=[('target', 'S20'), ('V_mag', '>f4')])
+        ind = np.array([False,  True,  True], dtype=bool)
+        assert_(d[ind].flags.writeable)
+        ind = np.array([0, 1])
+        assert_(d[ind].flags.writeable)
+        assert_(d[...].flags.writeable)
+        assert_(d[0].flags.writeable)
+
+
     def test_memory_order(self):
         # This is not necessary to preserve. Memory layouts for
         # more complex indices are not as simple.