Add derived unit

src/ifcopenshell-python/ifcopenshell/api/unit/__init__.py

@@ -28,6 +28,7 @@ from .add_context_dependent_unit import add_context_dependent_unit
 from .add_conversion_based_unit import add_conversion_based_unit
 from .add_monetary_unit import add_monetary_unit
 from .add_si_unit import add_si_unit
+from .add_derived_unit import add_derived_unit
 from .assign_unit import assign_unit
 from .edit_derived_unit import edit_derived_unit
 from .edit_monetary_unit import edit_monetary_unit
@@ -42,6 +43,7 @@ __all__ = [
     "add_conversion_based_unit",
     "add_monetary_unit",
     "add_si_unit",
+    "add_derived_unit",
     "assign_unit",
     "edit_derived_unit",
     "edit_monetary_unit",

src/ifcopenshell-python/ifcopenshell/api/unit/add_derived_unit.py

@@ -0,0 +1,80 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2021 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 ifcopenshell.util.unit
+from typing import Any, Optional
+
+
+def add_derived_unit(file: ifcopenshell.file, unit_type: str, userdefinedtype : str, attributes: dict[ifcopenshell.entity_instance, int]) -> ifcopenshell.entity_instance:
+    """Add a new Derive unit
+
+    The supported types are ANGULARVELOCITYUNIT, AREADENSITYUNIT, COMPOUNDPLANEANGLEUNIT,
+    DYNAMICVISCOSITYUNIT, HEATFLUXDENSITYUNIT, INTEGERCOUNTRATEUNIT, ISOTHERMALMOISTURECAPACITYUNIT,
+    KINEMATICVISCOSITYUNIT, LINEARVELOCITYUNIT, MASSDENSITYUNIT, MASSFLOWRATEUNIT, MOISTUREDIFFUSIVITYUNIT,
+    MOLECULARWEIGHTUNIT, SPECIFICHEATCAPACITYUNIT, THERMALADMITTANCEUNIT, THERMALCONDUCTANCEUNIT,
+    THERMALRESISTANCEUNIT, THERMALTRANSMITTANCEUNIT, VAPORPERMEABILITYUNIT, VOLUMETRICFLOWRATEUNIT,
+    ROTATIONALFREQUENCYUNIT, TORQUEUNIT, MOMENTOFINERTIAUNIT, LINEARMOMENTUNIT, LINEARFORCEUNIT,
+    PLANARFORCEUNIT, MODULUSOFELASTICITYUNIT, SHEARMODULUSUNIT, LINEARSTIFFNESSUNIT, ROTATIONALSTIFFNESSUNIT,
+    MODULUSOFSUBGRADEREACTIONUNIT, ACCELERATIONUNIT, CURVATUREUNIT, HEATINGVALUEUNIT, IONCONCENTRATIONUNIT,
+    LUMINOUSINTENSITYDISTRIBUTIONUNIT, MASSPERLENGTHUNIT, MODULUSOFLINEARSUBGRADEREACTIONUNIT,
+    MODULUSOFROTATIONALSUBGRADEREACTIONUNIT, PHUNIT, ROTATIONALMASSUNIT, SECTIONAREAINTEGRALUNIT,
+    SECTIONMODULUSUNIT, SOUNDPOWERLEVELUNIT, SOUNDPOWERUNIT, SOUNDPRESSURELEVELUNIT, SOUNDPRESSUREUNIT,
+    TEMPERATUREGRADIENTUNIT, TEMPERATURERATEOFCHANGEUNIT, THERMALEXPANSIONCOEFFICIENTUNIT, WARPINGCONSTANTUNIT,
+    WARPINGMOMENTUNIT, USERDEFINED.
+
+    In case of choosing USERDEFINED, the UserDefinedType parameter needs to be provided
+
+    :param unit_type: A type of unit chosen from the list above. For
+        example, choosing THERMALCONDUCTANCEUNIT will give you a Thermal conductance.
+    :type unit_type: str
+    :param userdefinedtype: The user defined type in case of choosing USERDEFINED, or None for no
+        user defined type.
+    :type userdefinedtype: str or None
+    :param attributes: a dictionary of attribute names and values.
+    :type attributes: dict
+    :return: The newly created IfcDerivedUnit
+    :rtype: ifcopenshell.entity_instance
+
+    Example:
+
+    .. code:: python
+
+        # Linear velocity in m/s
+        length = ifcopenshell.api.unit.add_si_unit(model, unit_type="LENGTHUNIT")
+        #2=IfcSIUnit(*,.LENGTHUNIT.,$,.METRE.)
+
+        time = ifcopenshell.api.unit.add_si_unit(model, unit_type="TIMEUNIT")
+        #4=IfcSIUnit(*,.TIMEUNIT.,$,.SECOND.)
+
+        linear_velocity = ifcopenshell.api.unit.add_derived_unit(model, 'LINEARVELOCITY', None, {length : 1, time : -1})
+        #10=IfcDerivedUnitElement(#2, 1)
+        #11=IfcDerivedUnitElement(#4, -1)
+        #12=IfcDerivedUnit((#10,#11),.LINEARVELOCITY.,$)
+
+    """
+    settings = {"unit_type": unit_type, "attributes": attributes}
+    
+    derive_unit_elements = []
+
+    for named_unit in settings['attributes']:
+        derive_unit_elements.append(file.create_entity("IfcDerivedUnitElement", Unit=named_unit, Exponent = settings['attributes'][named_unit]))
+                                    
+    return file.create_entity("IfcDerivedUnit",
+                               Elements = derive_unit_elements,
+                               UnitType=settings["unit_type"],
+                               UserDefinedType=userdefinedtype)