Merge pull request #1163 from wright-group/issue-1105

constants propagate units

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/).
 
 ## [Unreleased]
 
+### Fixed
+- constants in chopped data will inherit the units of the original data
+
 ## [3.5.2]
 
 ### Added

WrightTools/data/_data.py

@@ -596,6 +596,11 @@ def _from_slice(self, idx, name=None, parent=None) -> Data:
 
         for const in list(self.constant_expressions) + constants:
             out.create_constant(const, verbose=False)
+            if const in self.constant_expressions:
+                dest_units = self.constants[self.constant_expressions.index(const)].units
+            else:
+                dest_units = self.axes[self.axis_expressions.index(const)].units
+            out.constants[out.constant_expressions.index(const)].convert(dest_units)
         for j, units in enumerate(new_axis_units):
             out.axes[j].convert(units)
 

tests/data/chop.py

@@ -111,8 +111,10 @@ def test_3D_to_2D_units():
         assert d.w2.size == 11
         assert d.axis_expressions == ("wm", "w2")
         assert d.units == ("eV", "eV")
-    data.close()
+        w1 = d.constants[d.constant_names.index("w1")]
+        assert w1.units == "eV"
     chop.close()
+    data.close()
 
 
 def test_parent():