Merge pull request #8030 from lesteve/fix-ma-median-with-only-one-non-masked-value

charris · web-flow · commit 3333e8b4a033 · 2016-09-07T12:38:23.000-05:00
BUG: fix np.ma.median with only one non-masked value and an axis argument
diff --git a/numpy/ma/extras.py b/numpy/ma/extras.py
@@ -727,9 +727,8 @@ def _median(a, axis=None, out=None, overwrite_input=False):
     ind = np.meshgrid(*axes_grid, sparse=True, indexing='ij')
 
     # insert indices of low and high median
-    ind.insert(axis, h - 1)
+    ind.insert(axis, np.maximum(0, h - 1))
     low = asorted[tuple(ind)]
-    low._sharedmask = False
     ind[axis] = h
     high = asorted[tuple(ind)]
 
diff --git a/numpy/ma/tests/test_extras.py b/numpy/ma/tests/test_extras.py
@@ -790,6 +790,15 @@ def test_out(self):
         assert_equal(r, out)
         assert_(type(r) == MaskedArray)
 
+    def test_single_non_masked_value_on_axis(self):
+        data = [[1., 0.],
+                [0., 3.],
+                [0., 0.]]
+        masked_arr = np.ma.masked_equal(data, 0)
+        expected = [1., 3.]
+        assert_array_equal(np.ma.median(masked_arr, axis=0),
+                           expected)
+
 
 class TestCov(TestCase):
 
