edgegraph.structure.universe.Universe

class edgegraph.structure.universe.Universe(*, vertices=None, laws=None, uid=None, attributes=None)

Bases: Vertex

Represents a universe that can contain vertices and links.

This is the container of vertices. It may also reasonably be called a “graph” object – the collection of all edges and vertices under examination at any given moment. However, it is more flexible in implementation, and can actually contain any subclass of BaseObject (though they may not appear in graph-related operations, such as traversals or searches, if they do not subclass Vertex.)

Pay attention that this class itself is a subclass of Vertex; this means that while containing an entire graph (or more) on its own, this object can also be treated as a vertex inside another universe. In this way, you can create graphs of other graphs, even recursively if you like. Whether or not this is a good idea greatly depends on the situation, but the implementation allows it (this is a feature, not an implementation detail).

__init__(*, vertices=None, laws=None, uid=None, attributes=None)

Instantiate a Universe.

Parameters:

• vertices (set[Vertex] | None) – a set of vertices to link to this universe

• laws (UniverseLaws | None) – the laws of nature that apply to this universe

See also

• edgegraph.structure.vertex.Vertex.__init__(), the superclass constructor

Methods

__init__(*[, vertices, laws, uid, attributes])	Instantiate a Universe.
add_to_link(link)	Add this vertex to a link.
add_to_universe(universe)	Adds this object to a new universe.
add_vertex(vert)	Adds a new vertex to this universe.
remove_from_link(link)	Remove this vertex from a link.
remove_from_universe(universe)	Remove this vertex from the specified universe.
remove_vertex(vert)	Remove a vertex from this universe.
total_cache_stats()	Return a ready-to-print summary of caching statistics.

Attributes

NEIGHBOR_CACHING	Enable / disable neighbor caching program-wide.
laws	Get the laws of this universe.
links	Return a tuple of links that are attached to this object.
uid	Get the UID of this object.
universes	Get the universes this object belongs to.
vertices	Return a (frozen) set of the vertices in this universe.

NEIGHBOR_CACHING: bool = False

Enable / disable neighbor caching program-wide.

See also

Vertex neighbor caching for more information on usage

add_to_link(link)

Add this vertex to a link.

Roughly equivalent to calling the Link’s add_vertex() with this object as an argument.

If the given link is already associated with this vertex, no action is taken.

Attention

Duplicate links ARE allowed! However, the same link twice is not. The difference is that of a == vs is comparison. == duplicate links are allowed, is duplicate links are ignored.

Parameters:

link (Link) – the link to add this vertex to

add_to_universe(universe)

Adds this object to a new universe. If it is already there, no action is taken.

In addition to the action(s) taken by the superclass (add_to_universe()), this method also adds this vertex to the universes’ reference of vertices, if needed.

Parameters:

universe (Universe) – the new universe to add this object to

add_vertex(vert)

Adds a new vertex to this universe.

The vertex in question will automatically have its universes updated to include this one, if needed.

Parameters:

vert (Vertex) – the vertex to be added

property laws: UniverseLaws | None

Get the laws of this universe.

property links: tuple[Link, ...]

Return a tuple of links that are attached to this object.

A tuple is given specifically to prevent the addition or removal of link objects using this attribute; it is intended to be immutable.

remove_from_link(link)

Remove this vertex from a link.

Parameters:

link (Link) – the link to remove this vertex from.

remove_from_universe(universe)

Remove this vertex from the specified universe.

In addition to the superclass method, also removes the vertex from the universe’s record of vertices as well as simply removing the universe from this vertices’ record of universes if necessary.

Parameters:

universe (Universe) – the universe that this vertex will be removed from

Raises:

KeyError – if this object is not present in the given universe

remove_vertex(vert)

Remove a vertex from this universe.

The vertex in question will be removed from this universe’s record of vertices. If necessary. this universe will then be removed from the vertices’ record of universes as well.

Parameters:

vert (Vertex) – the vertex to be removed

classmethod total_cache_stats()

Return a ready-to-print summary of caching statistics.

This function can be used to get human-readable cache statistics for the quick-access neighbor caching. It returns a string intended to be printed, logged, or written to file (it does not do anything other than build the string on its own).

See also

• Vertex neighbor caching for more on caching

• NEIGHBOR_CACHING to enable / disable it

Returns:

Human-readable string indicating size, hits, misses, invalidations, and insertions to the vertex neighbor cache.

Return type:

str

property uid: int

Get the UID of this object.

property universes: frozenset[Universe]

Get the universes this object belongs to.

Note that this gives you a frozenset; you cannot add or remove universes from this attribute.

See also

add_to_universe(), remove_from_universe() to add or remove this object from a given universe

property vertices

Return a (frozen) set of the vertices in this universe.

Return type:

frozenset[Vertex]