pythonocc基础使用：导入模型——ifc格式（ifcopenshell）

借用pythonocc强大的内核功能，我们同样可以读取建筑CAD信息，ifc 格式。
此处我们将参考ifcopenshell https://github.com/IfcOpenShell/IfcOpenShell
由于我们之前已经安装了pythonocc环境，因此在此基础上直接安装ifcopenshell

conda create -n pythonocc -c conda-forge -c tpaviot -c 3dhubs -c pythonocc -c ifcopenshell -c dlr-sc -c oce pythonocc-core=0.18.2 ifcopenshell python=3.5

如果使用jupyternotebook 还需要使用pythreejs
-c conda-forge pythreejs

但是在使用后，会提示在linux 64位上并不能编译，不是很清楚原因。。

Using the IfcOpenShell Python interface

$ wget -O duplex.zip http://projects.buildingsmartalliance.org/files/?artifact_id=4278
$ unzip duplex.zip
$ python
>>> import ifcopenshell
>>> f = ifcopenshell.open("Duplex_A_20110907_optimized.ifc")
>>>
>>> # Accessing entity instances by type:
>>> f.by_type("ifcwall")[:2]
[#91=IfcWallStandardCase('2O2Fr$t4X7Zf8NOew3FL9r',#1,'Basic Wall:Interior - Partition (92mm Stud):144586',$,'Basic Wall:Interior - Partition (92mm Stud):128360',#5198,#18806,'144586'), #92=IfcWallStandardCase('2O2Fr$t4X7Zf8NOew3FLIE',#1,'Basic Wall:Interior - Partition (92mm Stud):143921',$,'Basic Wall:Interior - Partition (92mm Stud):128360',#5206,#18805,'143921')]
>>> wall = _[0]
>>> len(wall) # number of EXPRESS attributes
8
>>>
>>> # Accessing EXPRESS attributes by name:
>>> wall.GlobalId 
'2O2Fr$t4X7Zf8NOew3FL9r'
>>> wall.Name = "My wall"
>>> wall.NonExistingAttr
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File ".\\ifcopenshell.py", line 14, in __getattr__
    except: raise AttributeError("entity instance of type '%s' has no attribute'%s'"%(self.wrapped_data.is_a(), name)) from None
AttributeError: entity instance of type 'IfcWallStandardCase' has no attribute 'NonExistingAttr'
>>> wall.GlobalId = 3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File ".\\ifcopenshell.py", line 26, in __setattr__
    self[self.wrapped_data.get_argument_index(key)] = value
  File ".\\ifcopenshell.py", line 30, in __setitem__
    self.wrapped_data.set_argument(idx, entity_instance.map_value(value))
  File ".\\ifc_wrapper.py", line 118, in <lambda>
    set_argument = lambda self,x,y: self._set_argument(x) if y is None else self
._set_argument(x,y)
  File ".\\ifc_wrapper.py", line 114, in _set_argument
    def _set_argument(self, *args): return _ifc_wrapper.entity_instance__set_argument(self, *args)
RuntimeError: INT is not a valid type for 'GlobalId'
>>> # Creating new entity instances
>>> f.createIfcCartesianPoint(Coordinates=(1.0,1.5,2.0))
#27530=IfcCartesianPoint((1.,1.5,2.))
>>> 
>>> # Working with GlobalId attributes:
>>> import uuid
>>> ifcopenshell.guid.compress(uuid.uuid1().hex)
'3x4C8Q_6qHuv$P$FYkANRX'
>>> new_guid = _
>>> owner_hist = f.by_type("IfcOwnerHistory")[0]
>>> new_wall = f.createIfcWallStandardCase(new_guid, owner_hist, None, None, Tag='my_tag')
>>> new_wall.ObjectType = ''
>>> new_wall.ObjectPlacement = new_wall.Representation = None
>>>
>>> # Accessing entity instances by instance id or GlobalId:
>>> f[92]
#92=IfcWallStandardCase('2O2Fr$t4X7Zf8NOew3FLIE',#1,'Basic Wall:Interior - Partition (92mm Stud):143921',$,'Basic Wall:Interior - Partition (92mm Stud):128360',#5206,#18805,'143921')
>>> f['2O2Fr$t4X7Zf8NOew3FLIE']
#92=IfcWallStandardCase('2O2Fr$t4X7Zf8NOew3FLIE',#1,'Basic Wall:Interior - Partition (92mm Stud):143921',$,'Basic Wall:Interior - Partition (92mm Stud):128360',#5206,#18805,'143921')
>>>
>>> # Writing IFC-SPF files to disk:
>>> f.write("out.ifc")