Type Aliases

PyHDC uses typed aliases throughout its API. They are defined in pyhdc.types and re-exported from pyhdc for convenience.

Core types

pyhdc.types.Backend

Backend = Literal["numpy", "torch"]

Specifies which array backend a hypervector or encoding uses.

pyhdc.types.ArrayLike

ArrayLike = Union[numpy.ndarray, torch.Tensor]

The raw array types that PyHDC can operate on. NumPy arrays are always supported; PyTorch tensors require TORCH_AVAILABLE = True.

pyhdc.types.Device

Device = Union[str, torch.device]

A device specification for PyTorch. Common values: "cpu", "cuda", "cuda:0", "cuda:1". Ignored when backend="numpy".

pyhdc.types.GeneratorOutputType

GeneratorOutputType = Literal["bits", "words", "floats"]

The type of values a generator produces. Each encoding family requires a specific output type from its generator. See the compatibility table in Random Number Generators.

Composite types

pyhdc.types.HypervectorLike

HypervectorLike = Union[Hypervector, List[Hypervector]]

Accepted anywhere a single hypervector or a list of hypervectors is valid.

pyhdc.types.HypervectorInput

HypervectorInput = Union[
    ArrayLike,
    Hypervector,
    List[Hypervector],
    List[List[Hypervector]],
]

The broadest input type for encoding methods like bundle and bind. Supports raw arrays, single hypervectors, flat lists, and nested lists for batched operations.

pyhdc.types.SimilarityResult

SimilarityResult = Union[float, ArrayLike, List[Union[float, ArrayLike]]]

The return type of similarity functions. A scalar float for single-pair comparisons; an array for batched comparisons; a list for list inputs.

pyhdc.types.SequenceType

SequenceType = Union[List[int], List[float], ArrayLike]

Used internally by the recovery module (not yet public).

Metadata types

pyhdc.types.OperationMetadata

OperationMetadata = Dict[str, Any]

The metadata dict attached to a Hypervector. Currently used by MBAT to store binding matrices under the key "matrices".

pyhdc.types.OperationResult

OperationResult = Union[ArrayLike, Tuple[ArrayLike, OperationMetadata]]

The return type of raw component functions. Most return a plain array; MBAT binding returns (array, metadata_dict).