return heat_index with temperature units

Unidata · Dec 7, 2023 · d9b68b9 · d9b68b9
1 parent f09de38
commit d9b68b9
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Showing 2 changed files with 9 additions and 5 deletions.
diff --git a/src/metpy/calc/basic.py b/src/metpy/calc/basic.py
@@ -251,7 +251,7 @@ def heat_index(temperature, relative_humidity, mask_undefined=True):
     >>> from metpy.calc import heat_index
     >>> from metpy.units import units
     >>> heat_index(30 * units.degC, 90 * units.percent)
-    <Quantity([105.3943646], 'degree_Fahrenheit')>
+    <Quantity([40.774647], 'degree_Celsius')>
     >>> heat_index(90 * units.degF, 90 * units.percent)
     <Quantity([121.901204], 'degree_Fahrenheit')>
     >>> heat_index(60 * units.degF, 90 * units.percent)
@@ -332,6 +332,9 @@ def heat_index(temperature, relative_humidity, mask_undefined=True):
                    * (units.Quantity(87., 'delta_degF') - delta[sel]))
         hi[sel] = hi[sel] + rh85adj
 
+    # Convert heat index to temperature units
+    hi = hi.to(temperature.units)
+
     # See if we need to mask any undefined values
     if mask_undefined:
         mask = np.array(temperature < units.Quantity(80., 'degF'))

diff --git a/tests/calc/test_basic.py b/tests/calc/test_basic.py
@@ -246,19 +246,20 @@ def test_heat_index_undefined_flag():
 
 
 def test_heat_index_units():
-    """Test units coming out of heat index."""
+    """Test units coming out of heat index are unchanged."""
     temp = units.Quantity([35., 20.], units.degC)
     rh = 70 * units.percent
     hi = heat_index(temp, rh)
-    assert_almost_equal(hi.to('degC'), units.Quantity([50.3405, np.nan], units.degC), 4)
+    assert hi.units == temp.units
+    assert_almost_equal(hi, units.Quantity([50.3405, np.nan], units.degC), 4)
 
 
 def test_heat_index_ratio():
     """Test giving humidity as number [0, 1] to heat index."""
     temp = units.Quantity([35., 20.], units.degC)
     rh = 0.7
     hi = heat_index(temp, rh)
-    assert_almost_equal(hi.to('degC'), units.Quantity([50.3405, np.nan], units.degC), 4)
+    assert_almost_equal(hi, units.Quantity([50.3405, np.nan], units.degC), 4)
 
 
 def test_heat_index_vs_nws():
@@ -278,7 +279,7 @@ def test_heat_index_kelvin():
     rh = 0.7
     hi = heat_index(temp, rh)
     # NB rounded up test value here vs the above two tests
-    assert_almost_equal(hi.to('degC'), 50.3406 * units.degC, 4)
+    assert_almost_equal(hi, 50.3406 * units.degC, 4)
 
 
 def test_height_to_geopotential(array_type):