From ae0316173aa0a95ed4ba6b07bc07d66a2e3ac592 Mon Sep 17 00:00:00 2001
From: Robb Traister <rtraister@citrine.io>
Date: Thu, 7 May 2026 16:23:03 -0400
Subject: [PATCH] add get_compatible_units function

---
 gemd/__version__.py        |  2 +-
 gemd/units/__init__.py     |  2 ++
 gemd/units/impl.py         | 17 +++++++++++++++++
 tests/units/test_parser.py | 14 ++++++++++++++
 4 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/gemd/__version__.py b/gemd/__version__.py
index ef6497d..3d67cd6 100644
--- a/gemd/__version__.py
+++ b/gemd/__version__.py
@@ -1 +1 @@
-__version__ = "2.3.2"
+__version__ = "2.4.0"
diff --git a/gemd/units/__init__.py b/gemd/units/__init__.py
index fc4bd89..425969a 100644
--- a/gemd/units/__init__.py
+++ b/gemd/units/__init__.py
@@ -3,6 +3,7 @@
     parse_units,
     convert_units,
     get_base_units,
+    get_compatible_units,
     change_definitions_file,
     UndefinedUnitError,
     IncompatibleUnitsError,
@@ -13,6 +14,7 @@
     "parse_units",
     "convert_units",
     "get_base_units",
+    "get_compatible_units",
     "change_definitions_file",
     "UndefinedUnitError",
     "IncompatibleUnitsError",
diff --git a/gemd/units/impl.py b/gemd/units/impl.py
index 3bcd789..1c608de 100644
--- a/gemd/units/impl.py
+++ b/gemd/units/impl.py
@@ -385,6 +385,23 @@ def get_base_units(units: Union[str, UnitRegistry.Unit]) -> Tuple[UnitRegistry.U
     return base_unit, float(ratio), offset
 
 
+def get_compatible_units(units: Union[str, UnitRegistry.Unit]) -> List[str]:
+    """Get all compatible units that match the dimensionality of the provided units.
+
+    Parameters
+    ----------
+    units: str, Unit
+        The representation of the object we wish to compare
+
+    Returns
+    -------
+    List[str]
+        A list of the compatible units.
+
+    """
+    return [f"{u}" for u in _REGISTRY.get_compatible_units(units)]
+
+
 def change_definitions_file(filename: str = None):
     """Change which file is used for units definition.
 
diff --git a/tests/units/test_parser.py b/tests/units/test_parser.py
index 031bc24..13db18f 100644
--- a/tests/units/test_parser.py
+++ b/tests/units/test_parser.py
@@ -13,6 +13,7 @@
     change_definitions_file,
     convert_units,
     get_base_units,
+    get_compatible_units,
     parse_units,
 )
 
@@ -191,6 +192,19 @@ def test_get_base_units():
     assert get_base_units("g / 25 mm") == (_REGISTRY("kg / m"), 0.04, 0)
 
 
+def test_get_compatible_units():
+    """Test that compatible units make sense."""
+    from gemd.units.impl import _REGISTRY
+    assert "kelvin" in get_compatible_units("degC")
+    assert "degree_Celsius" in get_compatible_units("degC")
+    assert "gram" in get_compatible_units("kg")
+    assert "meter" not in get_compatible_units("kg")
+    assert "meter" in get_compatible_units("km")
+    assert "meter" in get_compatible_units(_REGISTRY("km"))
+    assert "meter" in get_compatible_units("[length]")
+    assert "gram" not in get_compatible_units("km")
+
+
 @contextmanager
 def _change_units(filename):
     try: