visualdynamics.core.entities

entities

A geometry's entities, grouped the way the project tree lists them.

geometry.nodes, .coordinate_systems, .elements and .groups each return a view: the same rows that can be expanded in the tree, available to a script under the same names. A view reads the geometry's own arrays and is never a copy of them, so writing through a row writes into the geometry:

geometry.nodes[0].xyz = [0.0, 0.1, 0.0]     # moves the node
geometry.nodes.xyz[:, 2] += 0.5             # and so does this

A column has its plural name on the view and its singular name on a row: nodes.ids is every id, and nodes[3].id is one. Adding and deleting are passed to the geometry's own methods, which keep ids unique and make sure elements only refer to nodes that exist. All four kinds of entity are deleted by id.

Classes:

Name	Description
EntityRow	One node, coordinate system, element or element group of a geometry.
EntityView	One of a geometry's four kinds of entity, as rows and columns.

Classes

EntityRow

EntityRow(view: EntityView, row: int)

One node, coordinate system, element or element group of a geometry.

A row holds a row number, not the values, so it always reads and writes the geometry as it is now. If rows before it are deleted, it describes whatever entity moved into its position, so copy the values needed instead of keeping the row.

Attributes:

Name	Type	Description
row	int	The index of this entity in the geometry's arrays.

Source code in src/visualdynamics/core/entities.py

def __init__(self, view: EntityView, row: int) -> None:
    object.__setattr__(self, '_view', view)
    object.__setattr__(self, '_row', row)

Attributes

row property

row: int

The index of this entity in the geometry's arrays.

EntityView

EntityView(geometry: Geometry, kind: str)

One of a geometry's four kinds of entity, as rows and columns.

Returned by geometry.nodes, geometry.coordinate_systems, geometry.elements and geometry.groups. Iterating gives one EntityRow per entity. A column is read by its plural name and is the geometry's own array, so slicing and assigning into it edit the geometry in place.

Methods:

Name	Description
add	Add one entity through the geometry's own method.
delete	Delete entities by id, through the geometry's own method.

Attributes:

Name	Type	Description
columns	tuple[str, ...]	The plural names of this view's columns, in table order.

Source code in src/visualdynamics/core/entities.py

def __init__(self, geometry: Geometry, kind: str) -> None:
    self.geometry: Geometry = geometry
    self.kind: str = kind
    self._by_plural = {plural: attr
                       for plural, _single, attr in COLUMNS[kind]}
    self._by_singular = {single: attr
                         for _plural, single, attr in COLUMNS[kind]}

Attributes

columns property

columns: tuple[str, ...]

The plural names of this view's columns, in table order.

Methods:

add

add(*args: Any, **kwargs: Any) -> int

Add one entity through the geometry's own method.

The arguments and the return value are those of Geometry.add_node, add_coordinate_system, add_element or add_group: the new id, except for an element, which returns its row index. Those methods keep ids unique and check that an element's nodes exist.

Source code in src/visualdynamics/core/entities.py

def add(self, *args: Any, **kwargs: Any) -> int:
    """Add one entity through the geometry's own method.

    The arguments and the return value are those of
    `Geometry.add_node`, `add_coordinate_system`, `add_element` or
    `add_group`: the new id, except for an element, which returns its
    row index. Those methods keep ids unique and check that an
    element's nodes exist.
    """
    return getattr(self.geometry, VERBS[self.kind][0])(*args, **kwargs)

delete

delete(ids: Ids) -> None

Delete entities by id, through the geometry's own method.

Ids that are not present are ignored, so deleting twice is not an error.

Source code in src/visualdynamics/core/entities.py

def delete(self, ids: Ids) -> None:
    """Delete entities by id, through the geometry's own method.

    Ids that are not present are ignored, so deleting twice is not
    an error.
    """
    getattr(self.geometry, VERBS[self.kind][1])(ids)