BUG: Look up methods on MaskedArray in _frommethod

Fixes #8019

2 files changed, 19 insertions, 14 deletions

diff --git a/numpy/ma/core.py b/numpy/ma/core.py
index 1b25725d1..e87460521 100644
--- a/numpy/ma/core.py
+++ b/numpy/ma/core.py
@@ -6372,21 +6372,16 @@ class _frommethod:
     def __call__(self, a, *args, **params):
         if self.reversed:
             args = list(args)
-            arr = args[0]
-            args[0] = a
-            a = arr
-        # Get the method from the array (if possible)
+            a, args[0] = args[0], a
+
+        marr = asanyarray(a)
         method_name = self.__name__
-        method = getattr(a, method_name, None)
-        if method is not None:
-            return method(*args, **params)
-        # Still here ? Then a is not a MaskedArray
-        method = getattr(MaskedArray, method_name, None)
-        if method is not None:
-            return method(MaskedArray(a), *args, **params)
-        # Still here ? OK, let's call the corresponding np function
-        method = getattr(np, method_name)
-        return method(a, *args, **params)
+        method = getattr(type(marr), method_name, None)
+        if method is None:
+            # use the corresponding np function
+            method = getattr(np, method_name)
+
+        return method(marr, *args, **params)
 
 
 all = _frommethod('all')
diff --git a/numpy/ma/tests/test_core.py b/numpy/ma/tests/test_core.py
index 9d8002ed0..f9d032f09 100644
--- a/numpy/ma/tests/test_core.py
+++ b/numpy/ma/tests/test_core.py
@@ -433,6 +433,11 @@ class TestMaskedArray(TestCase):
         assert_not_equal(y._data.ctypes.data, x._data.ctypes.data)
         assert_not_equal(y._mask.ctypes.data, x._mask.ctypes.data)
 
+    def test_copy_on_python_builtins(self):
+        # Tests copy works on python builtins (issue#8019)
+        self.assertTrue(isMaskedArray(np.ma.copy([1,2,3])))
+        self.assertTrue(isMaskedArray(np.ma.copy((1,2,3))))
+
     def test_copy_immutable(self):
         # Tests that the copy method is immutable, GitHub issue #5247
         a = np.ma.array([1, 2, 3])
@@ -1032,6 +1037,11 @@ class TestMaskedArrayArithmetic(TestCase):
         assert_(res.dtype.type is np.intp)
         assert_raises(np.AxisError, ott.count, axis=1)
 
+    def test_count_on_python_builtins(self):
+        # Tests count works on python builtins (issue#8019)
+        assert_equal(3, count([1,2,3]))
+        assert_equal(2, count((1,2)))
+
     def test_minmax_func(self):
         # Tests minimum and maximum.
         (x, y, a10, m1, m2, xm, ym, z, zm, xf) = self.d