Endpoint

class Endpoint(node, position, **attr)

Bases: object

Endpoint at a given node and position, with optional attributes.

Endpoints are incidences of nodes in a planar diagram. Oriented variants are represented by subclasses IngoingEndpoint and OutgoingEndpoint.

Parameters:

• node (Hashable)

• position (int)

• attr (dict[str, Any])

node

Node identifier.

Type:

Hashable

position

Position index at the node (counter-clockwise order).

Type:

int

attr

Arbitrary endpoint attributes (e.g., colors).

Type:

dict[str, Any]

__init__(node, position, **attr)

Construct an endpoint.

Parameters:

• node (Hashable) – Node identifier.

• position (int) – Position index at the node.

• **attr (Any) – Arbitrary endpoint attributes.

Return type:

None

Methods

__init__(node, position, **attr)	Construct an endpoint.
get(key[, _Endpoint__default])	Return an attribute value with a default.
is_oriented()	Return whether this endpoint type is oriented.
reverse_type()	Return the opposite endpoint type.

Attributes

node
position
attr

node: Hashable

position: int

attr: dict[str, Any]

get(key, _Endpoint__default=None)

Return an attribute value with a default.

Parameters:

• key (str) – Attribute key.

• __default – Default value if key is missing.

• _Endpoint__default (Any)

Returns:

Any – Stored value or __default.

Return type:

Any

static reverse_type()

Return the opposite endpoint type.

Returns:

type[Endpoint] – For base Endpoint, returns Endpoint itself.

Return type:

type[Endpoint]

static is_oriented()

Return whether this endpoint type is oriented.

Returns:

bool – False for base Endpoint.

Return type:

bool