Merge pull request openmc-dev#1493 from drewejohnson/numpy-mul-fy

Disallow numpy ufuncs being applied directly to FissionYields

openmc/deplete/nuclide.py

@@ -533,6 +533,7 @@ def items(self):
         return zip(self.products, self.yields)
 
     def __add__(self, other):
+        """Add one set of fission yields to this set, return new yields"""
         if not isinstance(other, FissionYield):
             return NotImplemented
         new = FissionYield(self.products, self.yields.copy())
@@ -550,12 +551,14 @@ def __radd__(self, other):
         return self + other
 
     def __imul__(self, scalar):
+        """Scale these fission yields by a real scalar"""
         if not isinstance(scalar, Real):
             return NotImplemented
         self.yields *= scalar
         return self
 
     def __mul__(self, scalar):
+        """Return a new set of yields scaled by a real scalar"""
         if not isinstance(scalar, Real):
             return NotImplemented
         new = FissionYield(self.products, self.yields.copy())
@@ -568,3 +571,8 @@ def __rmul__(self, scalar):
     def __repr__(self):
         return "<{} containing {} products and yields>".format(
             self.__class__.__name__, len(self))
+
+    # Avoid greedy numpy operations like np.float64 * fission_yield
+    # converting this to an array on the fly. Force __rmul__ and
+    # __radd__. See issue #1492
+    __array_ufunc__ = None

tests/unit_tests/test_deplete_nuclide.py

@@ -149,12 +149,18 @@ def test_fission_yield_distribution():
     # __getitem__ return yields as a view into yield matrix
     assert orig_yields.yields.base is yield_dist.yield_matrix
 
-    # Fission yield feature uses scaled and incremented
+    # Scale and increment fission yields
     mod_yields = orig_yields * 2
     assert numpy.array_equal(orig_yields.yields * 2, mod_yields.yields)
     mod_yields += orig_yields
     assert numpy.array_equal(orig_yields.yields * 3, mod_yields.yields)
 
+    mod_yields = 2.0 * orig_yields
+    assert numpy.array_equal(orig_yields.yields * 2, mod_yields.yields)
+
+    mod_yields = numpy.float64(2.0) * orig_yields
+    assert numpy.array_equal(orig_yields.yields * 2, mod_yields.yields)
+
     # Failure modes for adding, multiplying yields
     similar = numpy.empty_like(orig_yields.yields)
     with pytest.raises(TypeError):