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"""
Contains decorators to deal with input features that aren't vectors.
"""
from functools import partial
from typing import Any, TypeVar, Union
import numpy as np
import torch
from gpytorch.models import GP
from vanguard import utils
from vanguard.base import GPController
from vanguard.decoratorutils import Decorator, process_args, wraps_class
from vanguard.warnings import warn_experimental
ControllerT = TypeVar("ControllerT", bound=GPController)
GPModelT = TypeVar("GPModelT", bound=GP)
[docs]
class HigherRankFeatures(Decorator):
"""
Make a :class:`~vanguard.base.gpcontroller.GPController` compatible with higher rank features.
GPyTorch assumes that input features are rank-1 (vectors) and a variety of
RuntimeErrors are thrown from different places in the code if this is not true.
This decorator modifies the gp model class to make it compatible with higher
rank features.
:Example:
>>> @HigherRankFeatures(2)
... class NewController(GPController):
... pass
"""
[docs]
def __init__(self, rank: int, **kwargs: Any) -> None:
"""
:param rank: The rank of the input features. Should be a positive integer.
"""
warn_experimental("The HigherRankFeatures decorator")
super().__init__(framework_class=GPController, required_decorators={}, **kwargs)
self.rank = rank
def _decorate_class(self, cls: type[ControllerT]) -> type[ControllerT]:
rank = self.rank
@wraps_class(cls)
class InnerClass(cls):
def __init__(self, *args: Any, **kwargs: Any) -> None:
all_parameters_as_kwargs = process_args(super().__init__, *args, **kwargs)
self.rng = utils.optional_random_generator(all_parameters_as_kwargs.pop("rng", None))
train_x = all_parameters_as_kwargs["train_x"]
self.gp_model_class = _HigherRankFeaturesModel(train_x.shape[-rank:])(self.gp_model_class)
kernel_class = all_parameters_as_kwargs.pop("kernel_class")
super().__init__(kernel_class=kernel_class, rng=self.rng, **all_parameters_as_kwargs)
return InnerClass
class _HigherRankFeaturesModel:
"""
A decorator for a model, enabling higher rank features.
GPyTorch assumes that input features are rank-1 (vectors) and a variety of
RuntimeErrors are thrown from different places in the code if this is not true.
This decorator can be applied to a GPyTorch model and deals with the feature
shapes to avoid these issues. The decorator intercepts the training data
and any data passed to ``__call__``, flattening it so that the shapes work out
correctly. The data are then returned to their native shape before any actual
computation (e.g. inside kernels) is performed.
"""
def __init__(self, shape: Union[tuple[int, ...], torch.Size]) -> None:
"""
:param shape: The native shape of a single data point.
"""
self.shape = tuple(shape)
self.flat_shape = int(np.prod(self.shape))
def __call__(self, model_cls: type[GPModelT]) -> type[GPModelT]:
shape = self.shape
flat_shape = self.flat_shape
_flatten = partial(self._flatten, item_shape=shape, item_flat_shape=flat_shape)
_unflatten = partial(self._unflatten, item_shape=shape)
@wraps_class(model_cls)
class InnerClass(model_cls):
def __init__(self, train_x: torch.Tensor, *args: Any, **kwargs: Any) -> None:
super().__init__(_flatten(train_x), *args, **kwargs)
def __call__(self, *args, **kwargs):
args = [_flatten(arg) for arg in args]
return super().__call__(*args, **kwargs)
def forward(self, x):
return super().forward(_unflatten(x))
return InnerClass
@staticmethod
def _flatten(tensor: torch.Tensor, item_shape: tuple[int, ...], item_flat_shape: int) -> torch.Tensor:
"""
Reshapes tensors to flat (rank - 1) features.
:param tensor: The tensor to reshape.
:param item_shape: The native shape of a single item.
:param item_flat_shape: The flatten length of a single item.
:returns: Reshape tensor.
"""
new_shape = tuple(tensor.shape[: -len(item_shape)])
new_shape = new_shape + (item_flat_shape,)
return tensor.reshape(new_shape)
@staticmethod
def _unflatten(tensor: torch.Tensor, item_shape: tuple[int, ...]) -> torch.Tensor:
"""
Reshapes flatten tensors to native feature shape.
:param tensor: The tensor to reshape.
:param item_shape: The native shape of a single item.
:returns: Reshape tensor.
"""
new_shape = tuple(tensor.shape[:-1])
new_shape = new_shape + item_shape
return tensor.reshape(new_shape)