Merge pull request #8142 from ahaldane/ma_mean_scalar

BUG: np.ma.mean and var should return scalar if no mask

2 files changed, 25 insertions, 3 deletions

diff --git a/numpy/ma/core.py b/numpy/ma/core.py
index 44b64bdc8..c4a54acb4 100644
--- a/numpy/ma/core.py
+++ b/numpy/ma/core.py
@@ -5057,7 +5057,7 @@ class MaskedArray(ndarray):
 
         if self._mask is nomask:
             result = super(MaskedArray, self).mean(axis=axis,
-                                                   dtype=dtype, **kwargs)
+                                                   dtype=dtype, **kwargs)[()]
         else:
             dsum = self.sum(axis=axis, dtype=dtype, **kwargs)
             cnt = self.count(axis=axis, **kwargs)
@@ -5134,8 +5134,14 @@ class MaskedArray(ndarray):
 
         # Easy case: nomask, business as usual
         if self._mask is nomask:
-            return self._data.var(axis=axis, dtype=dtype, out=out,
-                                  ddof=ddof, **kwargs)
+            ret = super(MaskedArray, self).var(axis=axis, dtype=dtype, out=out,
+                                               ddof=ddof, **kwargs)[()]
+            if out is not None:
+                if isinstance(out, MaskedArray):
+                    out.__setmask__(nomask)
+                return out
+            return ret
+
         # Some data are masked, yay!
         cnt = self.count(axis=axis, **kwargs) - ddof
         danom = self - self.mean(axis, dtype, keepdims=True)
diff --git a/numpy/ma/tests/test_core.py b/numpy/ma/tests/test_core.py
index be06e7230..a4887aaf0 100644
--- a/numpy/ma/tests/test_core.py
+++ b/numpy/ma/tests/test_core.py
@@ -3353,6 +3353,22 @@ class TestMaskedArrayMathMethods(TestCase):
         assert_almost_equal(z.filled(0), [[1, 0], [15, 16]])
         assert_almost_equal(z.mask, [[0, 1], [0, 0]])
 
+    def test_varmean_nomask(self):
+        # gh-5769
+        foo = array([1,2,3,4], dtype='f8')
+        bar = array([1,2,3,4], dtype='f8')
+        assert_equal(type(foo.mean()), np.float64)
+        assert_equal(type(foo.var()), np.float64)
+        assert((foo.mean() == bar.mean()) is np.bool_(True))
+
+        # check array type is preserved and out works
+        foo = array(np.arange(16).reshape((4,4)), dtype='f8')
+        bar = empty(4, dtype='f4')
+        assert_equal(type(foo.mean(axis=1)), MaskedArray)
+        assert_equal(type(foo.var(axis=1)), MaskedArray)
+        assert_(foo.mean(axis=1, out=bar) is bar)
+        assert_(foo.var(axis=1, out=bar) is bar)
+
     def test_varstd(self):
         # Tests var & std on MaskedArrays.
         (x, X, XX, m, mx, mX, mXX, m2x, m2X, m2XX) = self.d