BUG: Implemented MaskedArray.dot

MaskedArray used to inherit ndarray.dot which ignored masks in the operands.

Fixes issue #5185.

2 files changed, 17 insertions, 7 deletions

diff --git a/numpy/ma/core.py b/numpy/ma/core.py
index 79924351c..964636595 100644
--- a/numpy/ma/core.py
+++ b/numpy/ma/core.py
@@ -4522,6 +4522,22 @@ class MaskedArray(ndarray):
             return D.astype(dtype).filled(0).sum(axis=None, out=out)
     trace.__doc__ = ndarray.trace.__doc__
 
+    def dot(self, other, out=None):
+        am = ~getmaskarray(self)
+        bm = ~getmaskarray(other)
+        if out is None:
+            d = np.dot(filled(self, 0), filled(other, 0))
+            m = ~np.dot(am, bm)
+            return masked_array(d, mask=m)
+        d = self.filled(0).dot(other.filled(0), out)
+        if out.mask.shape != d.shape:
+            out._mask = numpy.empty(d.shape, MaskType)
+        np.dot(am, bm, out._mask)
+        np.logical_not(out._mask, out._mask)
+        return out
+    dot.__doc__ = ndarray.dot.__doc__
+
+
     def sum(self, axis=None, dtype=None, out=None):
         """
         Return the sum of the array elements over the given axis.
diff --git a/numpy/ma/extras.py b/numpy/ma/extras.py
index 6d812964d..d389099ae 100644
--- a/numpy/ma/extras.py
+++ b/numpy/ma/extras.py
@@ -1047,13 +1047,7 @@ def dot(a, b, strict=False):
     if strict and (a.ndim == 2) and (b.ndim == 2):
         a = mask_rows(a)
         b = mask_cols(b)
-    #
-    d = np.dot(filled(a, 0), filled(b, 0))
-    #
-    am = (~getmaskarray(a))
-    bm = (~getmaskarray(b))
-    m = ~np.dot(am, bm)
-    return masked_array(d, mask=m)
+    return a.dot(b)
 
 #####--------------------------------------------------------------------------
 #---- --- arraysetops ---