You can now choose both input and output units for imperial formatting

src/ifcopenshell-python/ifcopenshell/util/selector.py

@@ -120,7 +120,7 @@ format_grammar = lark.Lark(
     round: "round(" function "," NUMBER ")"
     format_length: metric_length | imperial_length
     metric_length: "metric_length(" function "," NUMBER "," NUMBER ")"
-    imperial_length: "imperial_length(" function "," NUMBER ["," ESCAPED_STRING] ")"
+    imperial_length: "imperial_length(" function "," NUMBER ["," ESCAPED_STRING "," ESCAPED_STRING] ")"
     lower: "lower(" function ")"
     upper: "upper(" function ")"
     title: "title(" function ")"
@@ -195,17 +195,15 @@ class FormatTransformer(lark.Transformer):
 
     def imperial_length(self, args):
         if len(args) == 2:
-            imperial_unit = "foot"
+            input_unit = "foot"
             value, precision = args
         else:
-            value, precision, imperial_unit = args
+            value, precision, input_unit, output_unit = args
-            if imperial_unit == "inch":
+            input_unit = "inch" if input_unit == "inch" else "foot"
-                imperial_unit = "inch"
+            output_unit = "inch" if output_unit == "inch" else "foot"
-            else:
-                imperial_unit = "foot"
 
         return ifcopenshell.util.unit.format_length(
-            float(value), int(precision), unit_system="imperial", imperial_unit=imperial_unit
+            float(value), int(precision), unit_system="imperial", input_unit=input_unit, output_unit=output_unit
         )
 
 
@@ -821,7 +819,7 @@ class Selector:
                     key = "LayerSetName"  # This oddity in the IFC spec is annoying so we account for it.
 
                 if isinstance(key, re.Pattern):
-                    attribute = None # Should we support regex attributes? Probably not for now.
+                    attribute = None  # Should we support regex attributes? Probably not for now.
                 else:
                     attribute = getattr(value, key, None)
 

src/ifcopenshell-python/ifcopenshell/util/unit.py

@@ -548,12 +548,18 @@ def calculate_unit_scale(ifc_file):
 
 
 def format_length(
-    value, precision, decimal_places=2, suppress_zero_inches=True, unit_system="imperial", imperial_unit="foot"
+    value,
+    precision,
+    decimal_places=2,
+    suppress_zero_inches=True,
+    unit_system="imperial",
+    input_unit="foot",
+    output_unit="foot",
 ):
     """Formats a length for readability and imperial formatting
 
     :param value: The value in meters if metric, or either decimal feet or
-        inches if imperial depending on imperial_unit.
+        inches if imperial depending on input_unit.
     :type value: float
     :param precision: How precise the format should be. I.e. round to nearest.
         For imperial, it is 1/Nth. E.g. 12 means to the nearest 1/12th of an
@@ -566,15 +572,18 @@ def format_length(
     :type suppress_zero_inches: bool
     :param unit_system: Choose whether your value is "metric" or "imperial"
     :type unit_system: str
-    :param imperial_unit: If imperial, specify whether your value is "foot" or
+    :param input_unit: If imperial, specify whether your value is "foot" or
         "inch".
-    :type imperial_unit: str
+    :type input_unit: str
+    :param output_unit: If imperial, specify whether your value is "foot" to
+        format as both feet and inches, or "inch" if only inches should be
+        shown.
     """
     if unit_system == "imperial":
-        if imperial_unit == "foot":
+        if input_unit == "foot":
             feet = int(value)
             inches = (value - feet) * 12
-        elif imperial_unit == "inch":
+        elif input_unit == "inch":
             inches = value % 12
             feet = int(round((value - inches) / 12))
 
@@ -587,13 +596,21 @@ def format_length(
         # If fraction is a whole number, format it accordingly
         if frac.denominator == 1:
             if suppress_zero_inches and frac.numerator == 0:
-                return f"{feet}'"
+                if output_unit == "foot":
-            return f"{feet}' - {frac.numerator}\""
+                    return f"{feet}'"
+                return f'{feet * 12}"'
+            if output_unit == "foot":
+                return f"{feet}' - {frac.numerator}\""
+            return f'{(feet * 12) + frac.numerator}"'
         if frac.numerator > frac.denominator:
             remainder = frac.numerator % frac.denominator
             whole = int((frac.numerator - remainder) / frac.denominator)
-            return f"{feet}' - {whole} {remainder}/{frac.denominator}\""
+            if output_unit == "foot":
-        return f"{feet}' - {frac.numerator}/{frac.denominator}\""
+                return f"{feet}' - {whole} {remainder}/{frac.denominator}\""
+            return f'{(feet * 12) + whole} {remainder}/{frac.denominator}"'
+        if output_unit == "foot":
+            return f"{feet}' - {frac.numerator}/{frac.denominator}\""
+        return f'{feet * 12} {frac.numerator}/{frac.denominator}"'
     elif unit_system == "metric":
         rounded_val = round(value / precision) * precision
         return f"{rounded_val:.{decimal_places}f}"

src/ifcopenshell-python/test/util/test_selector.py

@@ -45,7 +45,8 @@ class TestFormat():
         assert subject.format('imperial_length(3.123, 1)') == "3' - 1\""
         assert subject.format('imperial_length(3.123, 2)') == "3' - 1 1/2\""
         assert subject.format('imperial_length(\"3.123\", 2)') == "3' - 1 1/2\""
-        assert subject.format('imperial_length(\"123.123\", 2, \"inch\")') == "10' - 3\""
+        assert subject.format('imperial_length(\"123.123\", 2, \"inch\", \"foot\")') == "10' - 3\""
+        assert subject.format('imperial_length(\"123.123\", 2, \"inch\", \"inch\")') == "123\""
 
 
 class TestGetElementValue(test.bootstrap.IFC4):

src/ifcopenshell-python/test/util/test_unit.py

@@ -0,0 +1,59 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2023 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import pytest
+import test.bootstrap
+import ifcopenshell.api
+import ifcopenshell.util.unit as subject
+
+
+class TestFormatLength(test.bootstrap.IFC4):
+    def test_run(self):
+        assert subject.format_length(1, 1, decimal_places=0, unit_system="metric") == "1"
+        assert subject.format_length(1, 1, decimal_places=2, unit_system="metric") == "1.00"
+        assert subject.format_length(3, 5, decimal_places=2, unit_system="metric") == "5.00"
+        assert subject.format_length(3.123, 0.01, decimal_places=2, unit_system="metric") == "3.12"
+
+        assert subject.format_length(3, 1, unit_system="imperial", input_unit="foot") == "3'"
+        assert subject.format_length(3.5, 1, unit_system="imperial", input_unit="foot") == "3' - 6\""
+        assert subject.format_length(3.123, 1, unit_system="imperial", input_unit="foot") == "3' - 1\""
+        assert subject.format_length(3.123, 2, unit_system="imperial", input_unit="foot") == "3' - 1 1/2\""
+        assert subject.format_length(3.123, 4, unit_system="imperial", input_unit="foot") == "3' - 1 1/2\""
+        assert subject.format_length(3.123, 32, unit_system="imperial", input_unit="foot") == "3' - 1 15/32\""
+        assert subject.format_length(24, 1, unit_system="imperial", input_unit="inch") == "2'"
+        assert subject.format_length(25.23, 1, unit_system="imperial", input_unit="inch") == "2' - 1\""
+        assert subject.format_length(25.23, 4, unit_system="imperial", input_unit="inch") == "2' - 1 1/4\""
+
+        assert subject.format_length(3, 1, unit_system="imperial", input_unit="foot", output_unit="inch") == '36"'
+        assert subject.format_length(3.5, 1, unit_system="imperial", input_unit="foot", output_unit="inch") == '42"'
+        assert subject.format_length(3.123, 1, unit_system="imperial", input_unit="foot", output_unit="inch") == '37"'
+        assert (
+            subject.format_length(3.123, 2, unit_system="imperial", input_unit="foot", output_unit="inch") == '37 1/2"'
+        )
+        assert (
+            subject.format_length(3.123, 4, unit_system="imperial", input_unit="foot", output_unit="inch") == '37 1/2"'
+        )
+        assert (
+            subject.format_length(3.123, 32, unit_system="imperial", input_unit="foot", output_unit="inch")
+            == '37 15/32"'
+        )
+        assert subject.format_length(24, 1, unit_system="imperial", input_unit="inch", output_unit="inch") == '24"'
+        assert subject.format_length(25.23, 1, unit_system="imperial", input_unit="inch", output_unit="inch") == '25"'
+        assert (
+            subject.format_length(25.23, 4, unit_system="imperial", input_unit="inch", output_unit="inch") == '25 1/4"'
+        )