offsets as deltas

hgrecco · May 21, 2024 · b161850 · b161850
1 parent f2e4081
commit b161850
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Showing 3 changed files with 12 additions and 8 deletions.
diff --git a/pint/facets/numpy/numpy_func.py b/pint/facets/numpy/numpy_func.py
@@ -197,7 +197,7 @@ def get_op_output_unit(unit_op, first_input_units, all_args=None, size=None):
                 product /= x.units
         result_unit = product
     elif unit_op == "variance":
-        result_unit = ((1 * first_input_units + 1 * first_input_units) ** 2).units
+        result_unit = ((1 * first_input_units - 1 * first_input_units) ** 2).units
     elif unit_op == "square":
         result_unit = first_input_units**2
     elif unit_op == "sqrt":
@@ -429,7 +429,7 @@ def implementation(*args, **kwargs):
 ]
 copy_units_output_ufuncs = ["ldexp", "fmod", "mod", "remainder"]
 op_units_output_ufuncs = {
-    "var": "square",
+    "var": "variance",
     "multiply": "mul",
     "true_divide": "div",
     "divide": "div",
@@ -438,7 +438,7 @@ def implementation(*args, **kwargs):
     "cbrt": "cbrt",
     "square": "square",
     "reciprocal": "reciprocal",
-    "std": "sum",
+    "std": "delta",
     "sum": "sum",
     "cumsum": "sum",
     "matmul": "mul",

diff --git a/pint/testsuite/test_numpy.py b/pint/testsuite/test_numpy.py
@@ -850,7 +850,7 @@ def test_nanmedian_numpy_func(self):
         assert np.nanmedian(self.q_nan) == 2 * self.ureg.m
 
     def test_var(self):
-        assert self.q.var() == 1.25 * self.ureg.m**2
+        assert self.q_temperature.var() == 1.25 * self.ureg.delta_degC**2
 
     @helpers.requires_array_function_protocol()
     def test_var_numpy_func(self):
@@ -866,14 +866,18 @@ def test_std(self):
         helpers.assert_quantity_almost_equal(
             self.q.std(), 1.11803 * self.ureg.m, rtol=1e-5
         )
+        helpers.assert_quantity_almost_equal(
+            self.q_temperature.std(), 1.11803 * self.ureg.delta_degC, rtol=1e-5
+        )
 
     @helpers.requires_array_function_protocol()
     def test_std_numpy_func(self):
         helpers.assert_quantity_almost_equal(
             np.std(self.q), 1.11803 * self.ureg.m, rtol=1e-5
         )
-        with pytest.raises(OffsetUnitCalculusError):
-            np.std(self.q_temperature)
+        helpers.assert_quantity_almost_equal(
+            np.std(self.q_temperature) , 1.11803 * self.ureg.delta_degC, rtol=1e-5
+        )
 
     def test_cumprod(self):
         with pytest.raises(DimensionalityError):

diff --git a/pint/testsuite/test_numpy_func.py b/pint/testsuite/test_numpy_func.py
@@ -172,8 +172,8 @@ def test_op_output_unit_div(self):
 
     def test_op_output_unit_variance(self):
         assert get_op_output_unit("variance", self.ureg.m) == self.ureg.m**2
-        with pytest.raises(OffsetUnitCalculusError):
-            get_op_output_unit("variance", self.ureg.degC)
+        # with pytest.raises(OffsetUnitCalculusError):
+        assert get_op_output_unit("variance", self.ureg.degC) == self.ureg.delta_degC**2
 
     def test_op_output_unit_square(self):
         assert get_op_output_unit("square", self.ureg.m) == self.ureg.m**2