fea: add get_anom_formula_from_prototype_formula

aviary/wren/utils.py

@@ -359,6 +359,22 @@ def prototype_formula(composition: Composition) -> str:
     return anon
 
 
+def get_anom_formula_from_prototype_formula(prototype_formula: str) -> str:
+    """Get an anonymous formula from a prototype formula."""
+    subst = r"\g<1>1"
+    prototype_formula = re.sub(r"([A-z](?![0-9]))", subst, prototype_formula)
+    anom_list = ["".join(g) for _, g in groupby(prototype_formula, str.isalpha)]
+    counts = anom_list[1::2]
+    dummy = anom_list[0::2]
+
+    return "".join(
+        [
+            f"{d}{c}" if c != "1" else d
+            for d, c in zip(dummy, sorted(counts), strict=False)
+        ]
+    )
+
+
 def count_wyckoff_positions(aflow_label: str) -> int:
     """Count number of Wyckoff positions in Wyckoff representation.
 

tests/test_wyckoff_ops.py

@@ -10,7 +10,9 @@
     get_aflow_label_from_aflow,
     get_aflow_label_from_spglib,
     get_aflow_strs_from_iso_and_composition,
+    get_anom_formula_from_prototype_formula,
     get_isopointal_proto_from_aflow,
+    prototype_formula,
 )
 
 from .conftest import TEST_DIR
@@ -81,6 +83,14 @@ def test_get_aflow_strs_from_iso_and_composition(
     assert aflows == expected.split(" ")
 
 
+def test_prototype_formula():
+    assert prototype_formula(Composition("Ce2Al3GaPd4")) == "A3B2CD4"
+
+
+def test_get_anom_formula_from_prototype_formula():
+    assert get_anom_formula_from_prototype_formula("A3B2CD4") == "AB2C3D4"
+
+
 @pytest.mark.parametrize(
     "aflow_label, expected",
     [