Types and helpers

pbcgraph.core.types

Core types and translation-vector helpers.

The public API uses a small number of lightweight aliases:

Attributes:

Name	Type	Description
TVec		Integer translation vector (length dim).
NodeId		Hashable quotient-node identifier.
EdgeKey		Integer key identifying a directed edge in a multigraph.
NodeInst		Node instance in the infinite lift: (node_id, shift).

TVec module-attribute

TVec = Tuple[int, ...]

NodeId module-attribute

NodeId = Hashable

EdgeKey module-attribute

EdgeKey = int

NodeInst module-attribute

NodeInst = Tuple[NodeId, TVec]

zero_tvec

zero_tvec(dim: int) -> TVec

Return the zero translation vector of length dim.

validate_tvec

validate_tvec(tvec: Any, dim: int) -> None

Validate that tvec is an integer translation vector of dimension dim.

Accepts

• tuples/lists of integer-likes,
• 1D NumPy arrays,
• sequences containing NumPy integer scalars.

Parameters:

Name	Type	Description	Default
tvec	Any	Translation vector.	required
dim	int	Required dimension.	required

Raises:

Type	Description
ValueError	If tvec has wrong length, wrong shape, or non-integer entries.

Notes

• Entries must be instances of :class:numbers.Integral.
• bool is rejected (even though it is a subclass of int).
• This function validates only; containers store translation vectors internally as tuples of Python int.

add_tvec

add_tvec(a: TVec, b: TVec) -> TVec

Add two translation vectors.

sub_tvec

sub_tvec(a: TVec, b: TVec) -> TVec

Subtract two translation vectors.

neg_tvec

neg_tvec(a: TVec) -> TVec

Negate a translation vector.