Basics

Importing modules and classes

A Python .py file is created for every compas_fea model and analysis, which is where an empty Structure object is first instantiated and then populated with the components needed for the model. To import these components and to also use other helper functions from the core compas or compas_fea packages, import statements are needed in the first few lines of the Python file. For example, if the user wishes to use a CAD environment for extracting geometry or visualising analysis results, either of the following lines below could be written to use Rhinoceros or Blender. These imports will make a variety of functions available from the compas_fea.cad.blender and compas_fea.cad.rhino modules.

from compas_fea.cad import rhino  # import Rhinoceros support

from compas_fea.cad import blender  # import Blender support

It is useful to use packages, modules and functions from the core compas library, especially compas.geometry and compas.datastructure imports to help build the Structure object. Such imports will be seen in a variety of the example models to construct the Structure.

from compas.datastructures import Mesh  # make the compas Mesh datastructure available
from compas.geometry import distance_point_point  # function to measure distances between two points

There are also many functions from the core compas CAD packages that can be helpful for creating, editing or deleting objects and layers in the CAD workspace:

from compas_blender.utilities import clear_layers  # clear all objects from a given layer
from compas_blender.utilities import delete_objects  # delete specific objects from the scene

The most important imports will be for retrieving classes from compas_fea.structure, including the main Structure class itself. Imports, like with the main compas library, are always available from the second level, with embedded modules on the third level onwards, pulled up to the second level to enable this. This is particularly useful for all of the classes found in compas_fea.structure, as you do not need to know the package structure beyond this level. The special classes in compas_fea.structure are used to make important objects for the model and will be described in more detail throughout the various tutorial topics. Below are three imports that bring in the GeneralStep, PointLoad and Structure classes.

from compas_fea.structure import GeneralStep
from compas_fea.structure import PointLoad
from compas_fea.structure import Structure

Bringing all of the import considerations together, the top of the .py file might look something like:

from compas.datastructures import Mesh
from compas.geometry import distance_point_point
from compas_rhino.helpers import mesh_from_guid

from compas_fea.cad import rhino
from compas_fea.structure import BucklingStep
from compas_fea.structure import Concrete
from compas_fea.structure import ElementProperties as Properties
from compas_fea.structure import GeneralStep
from compas_fea.structure import GravityLoad
from compas_fea.structure import PointLoad
from compas_fea.structure import RectangularSection
from compas_fea.structure import RollerDisplacementY
from compas_fea.structure import ShellSection
from compas_fea.structure import Steel
from compas_fea.structure import Structure
from compas_fea.structure import TrussSection