Adds tests for specific humidity and mixing ratio conversions

Author: daflack

tests/operators/test_humidity.py

@@ -0,0 +1,160 @@
+# © Crown copyright, Met Office (2022-2026) and CSET contributors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Test humidity operators."""
+
+import cf_units
+import iris.cube
+import numpy as np
+
+from CSET.operators import humidity
+
+
+def test_mixing_ratio_from_specific_humidity(specific_humidity_for_conversions_cube):
+    """Test calculation of mixing ratio from specific humidity."""
+    expected_data = specific_humidity_for_conversions_cube / (
+        1 - specific_humidity_for_conversions_cube
+    )
+    assert np.allclose(
+        expected_data.data,
+        humidity.mixing_ratio_from_specific_humidity(
+            specific_humidity_for_conversions_cube
+        ).data,
+        rtol=1e-6,
+        atol=1e-2,
+    )
+
+
+def test_mixing_ratio_from_specific_humidity_name(
+    specific_humidity_for_conversions_cube,
+):
+    """Test naming of mixing ratio cube."""
+    expected_name = "mixing_ratio"
+    assert (
+        expected_name
+        == humidity.mixing_ratio_from_specific_humidity(
+            specific_humidity_for_conversions_cube
+        ).name()
+    )
+
+
+def test_mixing_ratio_from_specific_humidity_unit(
+    specific_humidity_for_conversions_cube,
+):
+    """Test units for mixing ratio."""
+    expected_units = cf_units.Unit("kg/kg")
+    assert (
+        expected_units
+        == humidity.mixing_ratio_from_specific_humidity(
+            specific_humidity_for_conversions_cube
+        ).units
+    )
+
+
+def test_mixing_ratio_from_specific_humidity_cubelist(
+    specific_humidity_for_conversions_cube,
+):
+    """Test calculation of mixing ratio from specific humidity for a CubeList."""
+    expected_data = specific_humidity_for_conversions_cube / (
+        1 - specific_humidity_for_conversions_cube
+    )
+    expected_list = iris.cube.CubeList([expected_data, expected_data])
+    input_list = iris.cube.CubeList(
+        [specific_humidity_for_conversions_cube, specific_humidity_for_conversions_cube]
+    )
+    actual_cubelist = humidity.mixing_ratio_from_specific_humidity(input_list)
+    for cube_a, cube_b in zip(expected_list, actual_cubelist, strict=True):
+        assert np.allclose(cube_a.data, cube_b.data, rtol=1e-6, atol=1e-2)
+
+
+def test_mixing_ratio_from_specific_humidity_using_calculated(
+    mixing_ratio_for_conversions_cube,
+):
+    """Test mixing ratio calculation using calculated q from mixing ratio."""
+    calculated_w = humidity.mixing_ratio_from_specific_humidity(
+        humidity.specific_humidity_from_mixing_ratio(mixing_ratio_for_conversions_cube)
+    )
+    assert np.allclose(
+        mixing_ratio_for_conversions_cube.data, calculated_w.data, rtol=1e-6, atol=1e-2
+    )
+
+
+def test_specific_humidity_from_mixing_ratio(mixing_ratio_for_conversions_cube):
+    """Test specific humidity calculation from mixing ratio."""
+    expected_data = mixing_ratio_for_conversions_cube / (
+        1 + mixing_ratio_for_conversions_cube
+    )
+    assert np.allclose(
+        expected_data.data,
+        humidity.specific_humidity_from_mixing_ratio(
+            mixing_ratio_for_conversions_cube
+        ).data,
+        rtol=1e-6,
+        atol=1e-2,
+    )
+
+
+def test_specific_humidity_from_mixing_ratio_name(mixing_ratio_for_conversions_cube):
+    """Test specific humidity cube is named."""
+    expected_name = "specific_humidity"
+    assert (
+        expected_name
+        == humidity.specific_humidity_from_mixing_ratio(
+            mixing_ratio_for_conversions_cube
+        ).name()
+    )
+
+
+def test_specific_humidity_from_mixing_ratio_units(mixing_ratio_for_conversions_cube):
+    """Test units of specific humidity."""
+    expected_units = cf_units.Unit("kg/kg")
+    assert (
+        expected_units
+        == humidity.specific_humidity_from_mixing_ratio(
+            mixing_ratio_for_conversions_cube
+        ).units
+    )
+
+
+def test_specific_humidity_from_mixing_ratio_cubelist(
+    mixing_ratio_for_conversions_cube,
+):
+    """Test specific humidity calculation from mixing ratio with a CuebList."""
+    expected_data = mixing_ratio_for_conversions_cube / (
+        1 + mixing_ratio_for_conversions_cube
+    )
+    expected_list = iris.cube.CubeList([expected_data, expected_data])
+    input_list = iris.cube.CubeList(
+        [mixing_ratio_for_conversions_cube, mixing_ratio_for_conversions_cube]
+    )
+    actual_cubelist = humidity.specific_humidity_from_mixing_ratio(input_list)
+    for cube_a, cube_b in zip(expected_list, actual_cubelist, strict=True):
+        assert np.allclose(cube_a.data, cube_b.data, rtol=1e-6, atol=1e-2)
+
+
+def test_specific_humidity_from_mixing_ratio_using_calculated(
+    specific_humidity_for_conversions_cube,
+):
+    """Test specific humidity calculation using calculated w from specific humidity."""
+    calculated_q = humidity.specific_humidity_from_mixing_ratio(
+        humidity.mixing_ratio_from_specific_humidity(
+            specific_humidity_for_conversions_cube
+        )
+    )
+    assert np.allclose(
+        specific_humidity_for_conversions_cube.data,
+        calculated_q.data,
+        rtol=1e-6,
+        atol=1e-2,
+    )