Merge pull request #1539 from keewis/where-quantity-condition

avoid the `RecursionError` raised by `np.where`

CHANGES

@@ -11,6 +11,8 @@ Pint Changelog
   (Issue #1030, #574)
 - Added angular frequency documentation page.
 - Move ASV benchmarks to dedicated folder. (Issue #1542)
+- Fix a recursion error that would be raised when passing quantities to `cond` and `x`.
+  (Issue #1510, #1530)
 
 0.19.2 (2022-04-23)
 -------------------

pint/facets/numpy/numpy_func.py

@@ -552,6 +552,12 @@ def _interp(x, xp, fp, left=None, right=None, period=None):
 
 @implements("where", "function")
 def _where(condition, *args):
+    if not getattr(condition, "_is_multiplicative", True):
+        raise ValueError(
+            "Invalid units of the condition: Boolean value of Quantity with offset unit is ambiguous."
+        )
+
+    condition = getattr(condition, "magnitude", condition)
     args, output_wrap = unwrap_and_wrap_consistent_units(*args)
     return output_wrap(np.where(condition, *args))
 

pint/testsuite/test_numpy.py

@@ -1103,6 +1103,18 @@ def test_where(self):
                 0 * self.ureg.J,
             )
 
+        helpers.assert_quantity_equal(
+            np.where([-1, 0, 1] * self.ureg.m, [1, 2, 1] * self.ureg.s, np.nan),
+            [1, np.nan, 1] * self.ureg.s,
+        )
+        with pytest.raises(
+            ValueError,
+            match=".*Boolean value of Quantity with offset unit is ambiguous",
+        ):
+            np.where(
+                self.ureg.Quantity([-1, 0, 1], "degC"), [1, 2, 1] * self.ureg.s, np.nan
+            )
+
     @helpers.requires_array_function_protocol()
     def test_fabs(self):
         helpers.assert_quantity_equal(