botorch.utils¶
Constraints¶
Helpers for handling outcome constraints.
- botorch.utils.constraints.get_outcome_constraint_transforms(outcome_constraints)[source]¶
Create outcome constraint callables from outcome constraint tensors.
- Parameters
outcome_constraints (Optional[Tuple[torch.Tensor, torch.Tensor]]) – A tuple of (A, b). For k outcome constraints and m outputs at f(x)`, A is k x m and b is k x 1 such that A f(x) <= b.
- Returns
A list of callables, each mapping a Tensor of size b x q x m to a tensor of size b x q, where m is the number of outputs of the model. Negative values imply feasibility. The callables support broadcasting (e.g. for calling on a tensor of shape mc_samples x b x q x m).
- Return type
Optional[List[Callable[[torch.Tensor], torch.Tensor]]]
Example
>>> # constrain `f(x)[0] <= 0` >>> A = torch.tensor([[1., 0.]]) >>> b = torch.tensor([[0.]]) >>> outcome_constraints = get_outcome_constraint_transforms((A, b))
Containers¶
Containers to standardize inputs into models and acquisition functions.
- class botorch.utils.containers.TrainingData(Xs, Ys, Yvars=None)[source]¶
Bases:
object
Standardized container of model training data for models.
- Properties:
- Xs: A list of tensors, each of shape batch_shape x n_i x d,
where n_i is the number of training inputs for the i-th model.
- Ys: A list of tensors, each of shape batch_shape x n_i x 1,
where n_i is the number of training observations for the i-th (single-output) model.
- Yvars: A list of tensors, each of shape batch_shape x n_i x 1,
where n_i is the number of training observations of the observation noise for the i-th (single-output) model. If None, the observation noise level is unobserved.
- Parameters
Xs (List[torch.Tensor]) –
Ys (List[torch.Tensor]) –
Yvars (Optional[List[torch.Tensor]]) –
- Return type
None
- Xs: List[torch.Tensor]¶
- Ys: List[torch.Tensor]¶
- Yvars: Optional[List[torch.Tensor]] = None¶
- classmethod from_block_design(X, Y, Yvar=None)[source]¶
Construct a TrainingData object from a block design description.
- Parameters
X (torch.Tensor) – A batch_shape x n x d tensor of training points (shared across all outcomes).
Y (torch.Tensor) – A batch_shape x n x m tensor of training observations.
Yvar (Optional[torch.Tensor]) – A batch_shape x n x m tensor of training noise variance observations, or None.
- Returns
The TrainingData object (with is_block_design=True).
- property is_block_design: bool¶
Indicates whether training data is a “block design”.
Block designs are designs in which all outcomes are observed at the same training inputs.
- property X: torch.Tensor¶
The training inputs (block-design only).
This raises an UnsupportedError in the non-block-design case.
- property Y: torch.Tensor¶
The training observations (block-design only).
This raises an UnsupportedError in the non-block-design case.
- property Yvar: Optional[List[torch.Tensor]]¶
The training observations’s noise variance (block-design only).
This raises an UnsupportedError in the non-block-design case.
Objective¶
Helpers for handling objectives.
- botorch.utils.objective.get_objective_weights_transform(weights)[source]¶
Create a linear objective callable from a set of weights.
Create a callable mapping a Tensor of size b x q x m and an (optional) Tensor of size b x q x d to a Tensor of size b x q, where m is the number of outputs of the model using scalarization via the objective weights. This callable supports broadcasting (e.g. for calling on a tensor of shape mc_samples x b x q x m). For m = 1, the objective weight is used to determine the optimization direction.
- Parameters
weights (Optional[torch.Tensor]) – a 1-dimensional Tensor containing a weight for each task. If not provided, the identity mapping is used.
- Returns
Transform function using the objective weights.
- Return type
Callable[[torch.Tensor, Optional[torch.Tensor]], torch.Tensor]
Example
>>> weights = torch.tensor([0.75, 0.25]) >>> transform = get_objective_weights_transform(weights)
- botorch.utils.objective.apply_constraints_nonnegative_soft(obj, constraints, samples, eta)[source]¶
Applies constraints to a non-negative objective.
This function uses a sigmoid approximation to an indicator function for each constraint.
- Parameters
obj (torch.Tensor) – A n_samples x b x q Tensor of objective values.
constraints (List[Callable[[torch.Tensor], torch.Tensor]]) – A list of callables, each mapping a Tensor of size b x q x m to a Tensor of size b x q, where negative values imply feasibility. This callable must support broadcasting. Only relevant for multi- output models (m > 1).
samples (torch.Tensor) – A b x q x m Tensor of samples drawn from the posterior.
eta (float) – The temperature parameter for the sigmoid function.
- Returns
A n_samples x b x q-dim tensor of feasibility-weighted objectives.
- Return type
torch.Tensor
- botorch.utils.objective.soft_eval_constraint(lhs, eta=0.001)[source]¶
Element-wise evaluation of a constraint in a ‘soft’ fashion
value(x) = 1 / (1 + exp(x / eta))
- Parameters
lhs (torch.Tensor) – The left hand side of the constraint lhs <= 0.
eta (float) – The temperature parameter of the softmax function. As eta grows larger, this approximates the Heaviside step function.
- Returns
Element-wise ‘soft’ feasibility indicator of the same shape as lhs. For each element x, value(x) -> 0 as x becomes positive, and value(x) -> 1 as x becomes negative.
- Return type
torch.Tensor
- botorch.utils.objective.apply_constraints(obj, constraints, samples, infeasible_cost, eta=0.001)[source]¶
Apply constraints using an infeasible_cost M for negative objectives.
This allows feasibility-weighting an objective for the case where the objective can be negative by usingthe following strategy: (1) add M to make obj nonnegative (2) apply constraints using the sigmoid approximation (3) shift by -M
- Parameters
obj (torch.Tensor) – A n_samples x b x q Tensor of objective values.
constraints (List[Callable[[torch.Tensor], torch.Tensor]]) – A list of callables, each mapping a Tensor of size b x q x m to a Tensor of size b x q, where negative values imply feasibility. This callable must support broadcasting. Only relevant for multi- output models (m > 1).
samples (torch.Tensor) – A b x q x m Tensor of samples drawn from the posterior.
infeasible_cost (float) – The infeasible value.
eta (float) – The temperature parameter of the sigmoid function.
- Returns
A n_samples x b x q-dim tensor of feasibility-weighted objectives.
- Return type
torch.Tensor
Rounding¶
- botorch.utils.rounding.approximate_round(X, tau=0.001)[source]¶
Diffentiable approximate rounding function.
This method is a piecewise approximation of a rounding function where each piece is a hyperbolic tangent function.
- Parameters
X (torch.Tensor) – The tensor to round to the nearest integer (element-wise).
tau (float) – A temperature hyperparameter.
- Returns
The approximately rounded input tensor.
- Return type
torch.Tensor
Sampling¶
Utilities for MC and qMC sampling.
References
- Trikalinos2014polytope
T. A. Trikalinos and G. van Valkenhoef. Efficient sampling from uniform density n-polytopes. Technical report, Brown University, 2014.
- botorch.utils.sampling.manual_seed(seed=None)[source]¶
Contextmanager for manual setting the torch.random seed.
- Parameters
seed (Optional[int]) – The seed to set the random number generator to.
- Returns
Generator
- Return type
Generator[None, None, None]
Example
>>> with manual_seed(1234): >>> X = torch.rand(3)
- botorch.utils.sampling.construct_base_samples(batch_shape, output_shape, sample_shape, qmc=True, seed=None, device=None, dtype=None)[source]¶
Construct base samples from a multi-variate standard normal N(0, I_qo).
- Parameters
batch_shape (torch.Size) – The batch shape of the base samples to generate. Typically, this is used with each dimension of size 1, so as to eliminate sampling variance across batches.
output_shape (torch.Size) – The output shape (q x m) of the base samples to generate.
sample_shape (torch.Size) – The sample shape of the samples to draw.
qmc (bool) – If True, use quasi-MC sampling (instead of iid draws).
seed (Optional[int]) – If provided, use as a seed for the RNG.
device (Optional[torch.device]) –
dtype (Optional[torch.dtype]) –
- Returns
A sample_shape x batch_shape x mutput_shape dimensional tensor of base samples, drawn from a N(0, I_qm) distribution (using QMC if qmc=True). Here output_shape = q x m.
- Return type
torch.Tensor
Example
>>> batch_shape = torch.Size([2]) >>> output_shape = torch.Size([3]) >>> sample_shape = torch.Size([10]) >>> samples = construct_base_samples(batch_shape, output_shape, sample_shape)
- botorch.utils.sampling.construct_base_samples_from_posterior(posterior, sample_shape, qmc=True, collapse_batch_dims=True, seed=None)[source]¶
Construct a tensor of normally distributed base samples.
- Parameters
posterior (botorch.posteriors.posterior.Posterior) – A Posterior object.
sample_shape (torch.Size) – The sample shape of the samples to draw.
qmc (bool) – If True, use quasi-MC sampling (instead of iid draws).
seed (Optional[int]) – If provided, use as a seed for the RNG.
collapse_batch_dims (bool) –
- Returns
A num_samples x 1 x q x m dimensional Tensor of base samples, drawn from a N(0, I_qm) distribution (using QMC if qmc=True). Here q and m are the same as in the posterior’s event_shape b x q x m. Importantly, this only obtain a single t-batch of samples, so as to not introduce any sampling variance across t-batches.
- Return type
torch.Tensor
Example
>>> sample_shape = torch.Size([10]) >>> samples = construct_base_samples_from_posterior(posterior, sample_shape)
- botorch.utils.sampling.draw_sobol_samples(bounds, n, q, batch_shape=None, seed=None)[source]¶
Draw qMC samples from the box defined by bounds.
- Parameters
bounds (Tensor) – A 2 x d dimensional tensor specifying box constraints on a d-dimensional space, where bounds[0, :] and bounds[1, :] correspond to lower and upper bounds, respectively.
n (int) – The number of (q-batch) samples. As a best practice, use powers of 2.
q (int) – The size of each q-batch.
batch_shape (Optional[Iterable[int], torch.Size]) – The batch shape of the samples. If given, returns samples of shape n x batch_shape x q x d, where each batch is an n x q x d-dim tensor of qMC samples.
seed (Optional[int]) – The seed used for initializing Owen scrambling. If None (default), use a random seed.
- Returns
A n x batch_shape x q x d-dim tensor of qMC samples from the box defined by bounds.
- Return type
Tensor
Example
>>> bounds = torch.stack([torch.zeros(3), torch.ones(3)]) >>> samples = draw_sobol_samples(bounds, 16, 2)
- botorch.utils.sampling.draw_sobol_normal_samples(d, n, device=None, dtype=None, seed=None)[source]¶
Draw qMC samples from a multi-variate standard normal N(0, I_d)
A primary use-case for this functionality is to compute an QMC average of f(X) over X where each element of X is drawn N(0, 1).
- Parameters
d (int) – The dimension of the normal distribution.
n (int) – The number of samples to return. As a best practice, use powers of 2.
device (Optional[torch.device]) – The torch device.
dtype (Optional[torch.dtype]) – The torch dtype.
seed (Optional[int]) – The seed used for initializing Owen scrambling. If None (default), use a random seed.
- Returns
A tensor of qMC standard normal samples with dimension n x d with device and dtype specified by the input.
- Return type
torch.Tensor
Example
>>> samples = draw_sobol_normal_samples(2, 16)
- botorch.utils.sampling.sample_hypersphere(d, n=1, qmc=False, seed=None, device=None, dtype=None)[source]¶
Sample uniformly from a unit d-sphere.
- Parameters
d (int) – The dimension of the hypersphere.
n (int) – The number of samples to return.
qmc (bool) – If True, use QMC Sobol sampling (instead of i.i.d. uniform).
seed (Optional[int]) – If provided, use as a seed for the RNG.
device (Optional[torch.device]) – The torch device.
dtype (Optional[torch.dtype]) – The torch dtype.
- Returns
An n x d tensor of uniform samples from from the d-hypersphere.
- Return type
torch.Tensor
Example
>>> sample_hypersphere(d=5, n=10)
- botorch.utils.sampling.sample_simplex(d, n=1, qmc=False, seed=None, device=None, dtype=None)[source]¶
Sample uniformly from a d-simplex.
- Parameters
d (int) – The dimension of the simplex.
n (int) – The number of samples to return.
qmc (bool) – If True, use QMC Sobol sampling (instead of i.i.d. uniform).
seed (Optional[int]) – If provided, use as a seed for the RNG.
device (Optional[torch.device]) – The torch device.
dtype (Optional[torch.dtype]) – The torch dtype.
- Returns
An n x d tensor of uniform samples from from the d-simplex.
- Return type
torch.Tensor
Example
>>> sample_simplex(d=3, n=10)
- botorch.utils.sampling.sample_polytope(A, b, x0, n=10000, n0=100, seed=None)[source]¶
Hit and run sampler from uniform sampling points from a polytope, described via inequality constraints A*x<=b.
- Parameters
A (torch.Tensor) – A Tensor describing inequality constraints so that all samples satisfy Ax<=b.
b (torch.Tensor) – A Tensor describing the inequality constraints so that all samples satisfy Ax<=b.
x0 (torch.Tensor) – A d-dim Tensor representing a starting point of the chain satisfying the constraints.
n (int) – The number of resulting samples kept in the output.
n0 (int) – The number of burn-in samples. The chain will produce n+n0 samples but the first n0 samples are not saved.
seed (Optional[int]) – The seed for the sampler. If omitted, use a random seed.
- Returns
(n, d) dim Tensor containing the resulting samples.
- Return type
torch.Tensor
- botorch.utils.sampling.batched_multinomial(weights, num_samples, replacement=False, generator=None, out=None)[source]¶
Sample from multinomial with an arbitrary number of batch dimensions.
- Parameters
weights (torch.Tensor) – A batch_shape x num_categories tensor of weights. For each batch index i, j, …, this functions samples from a multinomial with input weights[i, j, …, :]. Note that the weights need not sum to one, but must be non-negative, finite and have a non-zero sum.
num_samples (int) – The number of samples to draw for each batch index. Must be smaller than num_categories if replacement=False.
replacement (bool) – If True, samples are drawn with replacement.
generator (Optional[torch._C.Generator]) – A a pseudorandom number generator for sampling.
out (Optional[torch.Tensor]) – The output tensor (optional). If provided, must be of size batch_shape x num_samples.
- Returns
A batch_shape x num_samples tensor of samples.
- Return type
torch.LongTensor
This is a thin wrapper around torch.multinomial that allows weight (input) tensors with an arbitrary number of batch dimensions (torch.multinomial only allows a single batch dimension). The calling signature is the same as for torch.multinomial.
Example
>>> weights = torch.rand(2, 3, 10) >>> samples = batched_multinomial(weights, 4) # shape is 2 x 3 x 4
- botorch.utils.sampling.find_interior_point(A, b, A_eq=None, b_eq=None)[source]¶
Find an interior point of a polytope via linear programming.
- Parameters
A (numpy.ndarray) – A n_ineq x d-dim numpy array containing the coefficients of the constraint inequalities.
b (numpy.ndarray) – A n_ineq x 1-dim numpy array containing the right hand sides of the constraint inequalities.
A_eq (Optional[numpy.ndarray]) – A n_eq x d-dim numpy array containing the coefficients of the constraint equalities.
b_eq (Optional[numpy.ndarray]) – A n_eq x 1-dim numpy array containing the right hand sides of the constraint equalities.
- Returns
A d-dim numpy array containing an interior point of the polytope. This function will raise a ValueError if there is no such point.
- Return type
numpy.ndarray
- This method solves the following Linear Program:
min -s subject to A @ x <= b - 2 * s, s >= 0, A_eq @ x = b_eq
- class botorch.utils.sampling.PolytopeSampler(inequality_constraints=None, equality_constraints=None, interior_point=None, bounds=None)[source]¶
Bases:
abc.ABC
Base class for samplers that sample points from a polytope.
Initialize PolytopeSampler.
- Parameters
inequality_constraints (Optional[Tuple[Tensor, Tensor]]) – Tensors (A, b) describing inequality constraints A @ x <= b, where A is a n_ineq_con x d-dim Tensor and b is a n_ineq_con x 1-dim Tensor, with n_ineq_con the number of inequalities and d the dimension of the sample space.
equality_constraints (Optional[Tuple[Tensor, Tensor]]) – Tensors (C, d) describing the equality constraints C @ x = d, where C is a n_eq_con x d-dim Tensor and d is a n_eq_con x 1-dim Tensor with n_eq_con the number of equalities.
interior_point (Optional[Tensor]) – A d_sample x 1-dim Tensor presenting a point in the (relative) interior of the polytope. If omitted, determined automatically by solving a Linear Program.
bounds (Optional[Tensor]) – A 2 x d-dim tensor of box bounds.
- Return type
None
- feasible(x)[source]¶
Check whether a point is contained in the polytope.
- Parameters
x (torch.Tensor) – A d x 1-dim Tensor.
- Returns
True if x is contained inside the polytope (incl. its boundary), False otherwise.
- Return type
bool
- class botorch.utils.sampling.HitAndRunPolytopeSampler(inequality_constraints=None, equality_constraints=None, interior_point=None, bounds=None, n_burnin=0)[source]¶
Bases:
botorch.utils.sampling.PolytopeSampler
A sampler for sampling from a polyope using a hit-and-run algorithm.
A sampler for sampling from a polyope using a hit-and-run algorithm.
- Parameters
inequality_constraints (Optional[Tuple[Tensor, Tensor]]) – Tensors (A, b) describing inequality constraints A @ x <= b, where A is a n_ineq_con x d-dim Tensor and b is a n_ineq_con x 1-dim Tensor, with n_ineq_con the number of inequalities and d the dimension of the sample space.
equality_constraints (Optional[Tuple[Tensor, Tensor]]) – Tensors (C, d) describing the equality constraints C @ x = d, where C is a n_eq_con x d-dim Tensor and d is a n_eq_con x 1-dim Tensor with n_eq_con the number of equalities.
interior_point (Optional[Tensor]) – A d_sample x 1-dim Tensor presenting a point in the (relative) interior of the polytope. If omitted, determined automatically by solving a Linear Program.
bounds (Optional[Tensor]) – A 2 x d-dim tensor of box bounds.
n_burnin (int) – The number of burn in samples.
- Return type
None
- class botorch.utils.sampling.DelaunayPolytopeSampler(inequality_constraints=None, equality_constraints=None, interior_point=None, bounds=None)[source]¶
Bases:
botorch.utils.sampling.PolytopeSampler
A polytope sampler using Delaunay triangulation.
This sampler first enumerates the vertices of the constraint polytope and then uses a Delaunay triangulation to tesselate its convex hull.
The sampling happens in two stages: 1. First, we sample from the set of hypertriangles generated by the Delaunay triangulation (i.e. which hyper-triangle to draw the sample from) with probabilities proportional to the triangle volumes. 2. Then, we sample uniformly from the chosen hypertriangle by sampling uniformly from the unit simplex of the appropriate dimension, and then computing the convex combination of the vertices of the hypertriangle according to that draw from the simplex.
The best reference (not exactly the same, but functionally equivalent) is [Trikalinos2014polytope]. A simple R implementation is available at https://github.com/gertvv/tesselample.
Initialize DelaunayPolytopeSampler.
- Parameters
inequality_constraints (Optional[Tuple[Tensor, Tensor]]) – Tensors (A, b) describing inequality constraints A @ x <= b, where A is a n_ineq_con x d-dim Tensor and b is a n_ineq_con x 1-dim Tensor, with n_ineq_con the number of inequalities and d the dimension of the sample space.
equality_constraints (Optional[Tuple[Tensor, Tensor]]) – Tensors (C, d) describing the equality constraints C @ x = d, where C is a n_eq_con x d-dim Tensor and d is a n_eq_con x 1-dim Tensor with n_eq_con the number of equalities.
interior_point (Optional[Tensor]) – A d_sample x 1-dim Tensor presenting a point in the (relative) interior of the polytope. If omitted, determined automatically by solving a Linear Program.
bounds (Optional[Tensor]) – A 2 x d-dim tensor of box bounds.
- Return type
None
Warning: The vertex enumeration performed in this algorithm can become extremely costly if there are a large number of inequalities. Similarly, the triangulation can get very expensive in high dimensions. Only use this algorithm for moderate dimensions / moderately complex constraint sets. An alternative is the HitAndRunPolytopeSampler.
- botorch.utils.sampling.get_polytope_samples(n, bounds, inequality_constraints=None, equality_constraints=None, seed=None, thinning=32, n_burnin=10000)[source]¶
Sample from polytope defined by box bounds and (in)equality constraints.
This uses a hit-and-run Markov chain sampler.
TODO: make this method return the sampler object, to avoid doing burn-in every time we draw samples.
- Parameters
n (int) – The number of samples.
bounds (torch.Tensor) – A 2 x d-dim tensor containing the box bounds.
constraints (equality) – A list of tuples (indices, coefficients, rhs), with each tuple encoding an inequality constraint of the form sum_i (X[indices[i]] * coefficients[i]) >= rhs.
constraints – A list of tuples (indices, coefficients, rhs), with each tuple encoding an inequality constraint of the form sum_i (X[indices[i]] * coefficients[i]) = rhs.
seed (Optional[int]) – The random seed.
thinning (int) – The amount of thinning.
n_burnin (int) – The number of burn-in samples for the Markov chain sampler.
inequality_constraints (Optional[List[Tuple[torch.Tensor, torch.Tensor, float]]]) –
equality_constraints (Optional[List[Tuple[torch.Tensor, torch.Tensor, float]]]) –
- Returns
A n x d-dim tensor of samples.
- Return type
torch.Tensor
- botorch.utils.sampling.sparse_to_dense_constraints(d, constraints)[source]¶
Convert parameter constraints from a sparse format into a dense format.
This method converts sparse triples of the form (indices, coefficients, rhs) to constraints of the form Ax >= b or Ax = b.
- Parameters
d (int) – The input dimension.
constraints (inequality) – A list of tuples (indices, coefficients, rhs), with each tuple encoding an (in)equality constraint of the form sum_i (X[indices[i]] * coefficients[i]) >= rhs or sum_i (X[indices[i]] * coefficients[i]) = rhs.
- Returns
A: A n_constraints x d-dim tensor of coefficients.
b: A n_constraints x 1-dim tensor of right hand sides.
- Return type
A two-element tuple containing
Sampling from GP priors¶
- class botorch.utils.gp_sampling.GPDraw(model, seed=None)[source]¶
Bases:
torch.nn.modules.module.Module
Convenience wrapper for sampling a function from a GP prior.
This wrapper implicitly defines the GP sample as a self-updating function by keeping track of the evaluated points and respective base samples used during the evaluation.
This does not yet support multi-output models.
Construct a GP function sampler.
- Parameters
model (Model) – The Model defining the GP prior.
seed (Optional[int]) –
- Return type
None
- property Xs: torch.Tensor¶
A (batch_shape) x n_eval x d-dim tensor of locations at which the GP was evaluated (or None if the sample has never been evaluated).
- property Ys: torch.Tensor¶
A (batch_shape) x n_eval x d-dim tensor of associated function values (or None if the sample has never been evaluated).
- forward(X)[source]¶
Evaluate the GP sample function at a set of points X.
- Parameters
X (torch.Tensor) – A batch_shape x n x d-dim tensor of points
- Returns
The value of the GP sample at the n points.
- Return type
torch.Tensor
- training: bool¶
- class botorch.utils.gp_sampling.RandomFourierFeatures(kernel, input_dim, num_rff_features)[source]¶
Bases:
torch.nn.modules.module.Module
A class that represents Random Fourier Features.
Initialize RandomFourierFeatures.
- Parameters
kernel (Kernel) – the GP kernel
input_dim (int) – the input dimension to the GP kernel
num_rff_features (int) – the number of fourier features
- Return type
None
- forward(X)[source]¶
Get fourier basis features for the provided inputs.
- Parameters
X (torch.Tensor) –
- Return type
torch.Tensor
- training: bool¶
- botorch.utils.gp_sampling.get_deterministic_model(weights, bases)[source]¶
Get a deterministic model using the provided weights and bases for each output.
- Parameters
weights (List[torch.Tensor]) – a list of weights with m elements
bases (List[botorch.utils.gp_sampling.RandomFourierFeatures]) – a list of RandomFourierFeatures with m elements.
- Returns
A deterministic model.
- Return type
- botorch.utils.gp_sampling.get_weights_posterior(X, y, sigma_sq)[source]¶
Sample bayesian linear regression weights.
- Parameters
X (torch.Tensor) – a n x num_rff_features-dim tensor of inputs
y (torch.Tensor) – a n-dim tensor of outputs
sigma_sq (float) – the noise variance
- Returns
The posterior distribution over the weights.
- Return type
torch.distributions.multivariate_normal.MultivariateNormal
- botorch.utils.gp_sampling.get_gp_samples(model, num_outputs, n_samples, num_rff_features=500)[source]¶
Sample functions from GP posterior using RFF.
- Parameters
model (botorch.models.model.Model) – the model
num_outputs (int) – the number of outputs
n_samples (int) – the number of sampled functions to draw
num_rff_features (int) – the number of random fourier features
- Returns
A list of sampled functions.
- Return type
List[botorch.models.deterministic.GenericDeterministicModel]
Testing¶
- class botorch.utils.testing.BotorchTestCase(methodName='runTest')[source]¶
Bases:
unittest.case.TestCase
Basic test case for Botorch.
- This
sets the default device to be torch.device(“cpu”)
ensures that no warnings are suppressed by default.
Create an instance of the class that will use the named test method when executed. Raises a ValueError if the instance does not have a method with the specified name.
- device = device(type='cpu')¶
- class botorch.utils.testing.BaseTestProblemBaseTestCase[source]¶
Bases:
object
- functions: List[botorch.test_functions.base.BaseTestProblem]¶
- class botorch.utils.testing.SyntheticTestFunctionBaseTestCase[source]¶
Bases:
botorch.utils.testing.BaseTestProblemBaseTestCase
- functions: List[botorch.test_functions.base.BaseTestProblem]¶
- class botorch.utils.testing.MockPosterior(mean=None, variance=None, samples=None)[source]¶
Bases:
botorch.posteriors.posterior.Posterior
Mock object that implements dummy methods and feeds through specified outputs
- property device: torch.device¶
The torch device of the posterior.
- property dtype: torch.dtype¶
The torch dtype of the posterior.
- property event_shape: torch.Size¶
The event shape (i.e. the shape of a single sample).
- property mean¶
The mean of the posterior as a (b) x n x m-dim Tensor.
- property variance¶
The variance of the posterior as a (b) x n x m-dim Tensor.
- class botorch.utils.testing.MockModel(posterior)[source]¶
Bases:
botorch.models.model.Model
Mock object that implements dummy methods and feeds through specified outputs
Initializes internal Module state, shared by both nn.Module and ScriptModule.
- Parameters
posterior (MockPosterior) –
- Return type
None
- posterior(X, output_indices=None, observation_noise=False)[source]¶
Computes the posterior over model outputs at the provided points.
- Note: The input transforms should be applied here using
self.transform_inputs(X) after the self.eval() call and before any model.forward or model.likelihood calls.
- Parameters
X (torch.Tensor) – A b x q x d-dim Tensor, where d is the dimension of the feature space, q is the number of points considered jointly, and b is the batch dimension.
output_indices (Optional[List[int]]) – A list of indices, corresponding to the outputs over which to compute the posterior (if the model is multi-output). Can be used to speed up computation if only a subset of the model’s outputs are required for optimization. If omitted, computes the posterior over all model outputs.
observation_noise (bool) – If True, add observation noise to the posterior.
- Returns
A Posterior object, representing a batch of b joint distributions over q points and m outputs each.
- Return type
- property num_outputs: int¶
The number of outputs of the model.
- property batch_shape: torch.Size¶
The batch shape of the model.
This is a batch shape from an I/O perspective, independent of the internal representation of the model (as e.g. in BatchedMultiOutputGPyTorchModel). For a model with m outputs, a test_batch_shape x q x d-shaped input X to the posterior method returns a Posterior object over an output of shape broadcast(test_batch_shape, model.batch_shape) x q x m.
- state_dict()[source]¶
Returns a dictionary containing a whole state of the module.
Both parameters and persistent buffers (e.g. running averages) are included. Keys are corresponding parameter and buffer names.
- Returns
a dictionary containing a whole state of the module
- Return type
dict
Example:
>>> module.state_dict().keys() ['bias', 'weight']
- load_state_dict(state_dict=None, strict=False)[source]¶
Copies parameters and buffers from
state_dict
into this module and its descendants. Ifstrict
isTrue
, then the keys ofstate_dict
must exactly match the keys returned by this module’sstate_dict()
function.- Parameters
state_dict (dict) – a dict containing parameters and persistent buffers.
strict (bool, optional) – whether to strictly enforce that the keys in
state_dict
match the keys returned by this module’sstate_dict()
function. Default:True
- Returns
missing_keys is a list of str containing the missing keys
unexpected_keys is a list of str containing the unexpected keys
- Return type
NamedTuple
withmissing_keys
andunexpected_keys
fields
- training: bool¶
- class botorch.utils.testing.MockAcquisitionFunction[source]¶
Bases:
object
Mock acquisition function object that implements dummy methods.
- class botorch.utils.testing.MultiObjectiveTestProblemBaseTestCase[source]¶
Bases:
botorch.utils.testing.BaseTestProblemBaseTestCase
- functions: List[botorch.test_functions.base.BaseTestProblem]¶
- class botorch.utils.testing.ConstrainedMultiObjectiveTestProblemBaseTestCase[source]¶
Bases:
botorch.utils.testing.MultiObjectiveTestProblemBaseTestCase
- functions: List[botorch.test_functions.base.BaseTestProblem]¶
Torch¶
- class botorch.utils.torch.BufferDict(buffers=None)[source]¶
Bases:
torch.nn.modules.module.Module
Holds buffers in a dictionary.
BufferDict can be indexed like a regular Python dictionary, but buffers it contains are properly registered, and will be visible by all Module methods.
BufferDict
is an ordered dictionary that respectsthe order of insertion, and
in
update()
, the order of the mergedOrderedDict
or anotherBufferDict
(the argument toupdate()
).
Note that
update()
with other unordered mapping types (e.g., Python’s plaindict
) does not preserve the order of the merged mapping.- Parameters
buffers (iterable, optional) – a mapping (dictionary) of (string :
Tensor
) or an iterable of key-value pairs of type (string,Tensor
)
Example:
class MyModule(nn.Module): def __init__(self): super(MyModule, self).__init__() self.buffers = nn.BufferDict({ 'left': torch.randn(5, 10), 'right': torch.randn(5, 10) }) def forward(self, x, choice): x = self.buffers[choice].mm(x) return x
Initializes internal Module state, shared by both nn.Module and ScriptModule.
- pop(key)[source]¶
Remove key from the BufferDict and return its buffer.
- Parameters
key (string) – key to pop from the BufferDict
- update(buffers)[source]¶
Update the
BufferDict
with the key-value pairs from a mapping or an iterable, overwriting existing keys.Note
If
buffers
is anOrderedDict
, aBufferDict
, or an iterable of key-value pairs, the order of new elements in it is preserved.- Parameters
buffers (iterable) – a mapping (dictionary) from string to
Tensor
, or an iterable of key-value pairs of type (string,Tensor
)
- extra_repr()[source]¶
Set the extra representation of the module
To print customized extra information, you should re-implement this method in your own modules. Both single-line and multi-line strings are acceptable.
- training: bool¶
Transformations¶
Some basic data transformation helpers.
- botorch.utils.transforms.squeeze_last_dim(Y)[source]¶
Squeeze the last dimension of a Tensor.
- Parameters
Y (torch.Tensor) – A … x d-dim Tensor.
- Returns
The input tensor with last dimension squeezed.
- Return type
torch.Tensor
Example
>>> Y = torch.rand(4, 3) >>> Y_squeezed = squeeze_last_dim(Y)
- botorch.utils.transforms.standardize(Y)[source]¶
Standardizes (zero mean, unit variance) a tensor by dim=-2.
If the tensor is single-dimensional, simply standardizes the tensor. If for some batch index all elements are equal (or if there is only a single data point), this function will return 0 for that batch index.
- Parameters
Y (torch.Tensor) – A batch_shape x n x m-dim tensor.
- Returns
The standardized Y.
- Return type
torch.Tensor
Example
>>> Y = torch.rand(4, 3) >>> Y_standardized = standardize(Y)
- botorch.utils.transforms.normalize(X, bounds)[source]¶
Min-max normalize X w.r.t. the provided bounds.
- Parameters
X (torch.Tensor) – … x d tensor of data
bounds (torch.Tensor) – 2 x d tensor of lower and upper bounds for each of the X’s d columns.
- Returns
- A … x d-dim tensor of normalized data, given by
(X - bounds[0]) / (bounds[1] - bounds[0]). If all elements of X are contained within bounds, the normalized values will be contained within [0, 1]^d.
- Return type
torch.Tensor
Example
>>> X = torch.rand(4, 3) >>> bounds = torch.stack([torch.zeros(3), 0.5 * torch.ones(3)]) >>> X_normalized = normalize(X, bounds)
- botorch.utils.transforms.unnormalize(X, bounds)[source]¶
Un-normalizes X w.r.t. the provided bounds.
- Parameters
X (torch.Tensor) – … x d tensor of data
bounds (torch.Tensor) – 2 x d tensor of lower and upper bounds for each of the X’s d columns.
- Returns
- A … x d-dim tensor of unnormalized data, given by
X * (bounds[1] - bounds[0]) + bounds[0]. If all elements of X are contained in [0, 1]^d, the un-normalized values will be contained within bounds.
- Return type
torch.Tensor
Example
>>> X_normalized = torch.rand(4, 3) >>> bounds = torch.stack([torch.zeros(3), 0.5 * torch.ones(3)]) >>> X = unnormalize(X_normalized, bounds)
- botorch.utils.transforms.normalize_indices(indices, d)[source]¶
Normalize a list of indices to ensure that they are positive.
- Parameters
indices (Optional[List[int]]) – A list of indices (may contain negative indices for indexing “from the back”).
d (int) – The dimension of the tensor to index.
- Returns
A normalized list of indices such that each index is between 0 and d-1, or None if indices is None.
- Return type
Optional[List[int]]
- botorch.utils.transforms.t_batch_mode_transform(expected_q=None, assert_output_shape=True)[source]¶
Factory for decorators taking a t-batched X tensor.
This method creates decorators for instance methods to transform an input tensor X to t-batch mode (i.e. with at least 3 dimensions). This assumes the tensor has a q-batch dimension. The decorator also checks the q-batch size if expected_q is provided, and the output shape if assert_output_shape is True.
- Parameters
expected_q (Optional[int]) – The expected q-batch size of X. If specified, this will raise an AssertionError if X’s q-batch size does not equal expected_q.
assert_output_shape (bool) – If True, this will raise an AssertionError if the output shape does not match either the t-batch shape of X, or the acqf.model.batch_shape for acquisition functions using batched models.
- Returns
The decorated instance method.
- Return type
Callable[[Callable[[Any, torch.Tensor], Any]], Callable[[Any, torch.Tensor], Any]]
Example
>>> class ExampleClass: >>> @t_batch_mode_transform(expected_q=1) >>> def single_q_method(self, X): >>> ... >>> >>> @t_batch_mode_transform() >>> def arbitrary_q_method(self, X): >>> ...
- botorch.utils.transforms.concatenate_pending_points(method)[source]¶
Decorator concatenating X_pending into an acquisition function’s argument.
This decorator works on the forward method of acquisition functions taking a tensor X as the argument. If the acquisition function has an X_pending attribute (that is not None), this is concatenated into the input X, appropriately expanding the pending points to match the batch shape of X.
Example
>>> class ExampleAcquisitionFunction: >>> @concatenate_pending_points >>> @t_batch_mode_transform() >>> def forward(self, X): >>> ...
- Parameters
method (Callable[[Any, torch.Tensor], Any]) –
- Return type
Callable[[Any, torch.Tensor], Any]
- botorch.utils.transforms.match_batch_shape(X, Y)[source]¶
Matches the batch dimension of a tensor to that of another tensor.
- Parameters
X (torch.Tensor) – A batch_shape_X x q x d tensor, whose batch dimensions that correspond to batch dimensions of Y are to be matched to those (if compatible).
Y (torch.Tensor) – A batch_shape_Y x q’ x d tensor.
- Returns
A batch_shape_Y x q x d tensor containing the data of X expanded to the batch dimensions of Y (if compatible). For instance, if X is b’’ x b’ x q x d and Y is b x q x d, then the returned tensor is b’’ x b x q x d.
- Return type
torch.Tensor
Example
>>> X = torch.rand(2, 1, 5, 3) >>> Y = torch.rand(2, 6, 4, 3) >>> X_matched = match_batch_shape(X, Y) >>> X_matched.shape torch.Size([2, 6, 5, 3])
Feasible Volume¶
- botorch.utils.feasible_volume.get_feasible_samples(samples, inequality_constraints=None)[source]¶
Checks which of the samples satisfy all of the inequality constraints.
- Parameters
samples (torch.Tensor) – A sample size x d size tensor of feature samples, where d is a feature dimension.
constraints (inequality) – A list of tuples (indices, coefficients, rhs), with each tuple encoding an inequality constraint of the form sum_i (X[indices[i]] * coefficients[i]) >= rhs.
inequality_constraints (Optional[List[Tuple[torch.Tensor, torch.Tensor, float]]]) –
- Returns
2-element tuple containing
Samples satisfying the linear constraints.
Estimated proportion of samples satisfying the linear constraints.
- Return type
Tuple[torch.Tensor, float]
- botorch.utils.feasible_volume.get_outcome_feasibility_probability(model, X, outcome_constraints, threshold=0.1, nsample_outcome=1000, seed=None)[source]¶
Monte Carlo estimate of the feasible volume with respect to the outcome constraints.
- Parameters
model (botorch.models.model.Model) – The model used for sampling the posterior.
X (torch.Tensor) – A tensor of dimension batch-shape x 1 x d, where d is feature dimension.
outcome_constraints (List[Callable[[torch.Tensor], torch.Tensor]]) – A list of callables, each mapping a Tensor of dimension sample_shape x batch-shape x q x m to a Tensor of dimension sample_shape x batch-shape x q, where negative values imply feasibility.
threshold (float) – A lower limit for the probability of posterior samples feasibility.
nsample_outcome (int) – The number of samples from the model posterior.
seed (Optional[int]) – The seed for the posterior sampler. If omitted, use a random seed.
- Returns
Estimated proportion of features for which posterior samples satisfy given outcome constraints with probability above or equal to the given threshold.
- Return type
float
- botorch.utils.feasible_volume.estimate_feasible_volume(bounds, model, outcome_constraints, inequality_constraints=None, nsample_feature=1000, nsample_outcome=1000, threshold=0.1, verbose=False, seed=None, device=None, dtype=None)[source]¶
Monte Carlo estimate of the feasible volume with respect to feature constraints and outcome constraints.
- Parameters
bounds (torch.Tensor) – A 2 x d tensor of lower and upper bounds for each column of X.
model (botorch.models.model.Model) – The model used for sampling the outcomes.
outcome_constraints (List[Callable[[torch.Tensor], torch.Tensor]]) – A list of callables, each mapping a Tensor of dimension sample_shape x batch-shape x q x m to a Tensor of dimension sample_shape x batch-shape x q, where negative values imply feasibility.
constraints (inequality) – A list of tuples (indices, coefficients, rhs), with each tuple encoding an inequality constraint of the form sum_i (X[indices[i]] * coefficients[i]) >= rhs.
nsample_feature (int) – The number of feature samples satisfying the bounds.
nsample_outcome (int) – The number of outcome samples from the model posterior.
threshold (float) – A lower limit for the probability of outcome feasibility
seed (Optional[int]) – The seed for both feature and outcome samplers. If omitted, use a random seed.
verbose (bool) – An indicator for whether to log the results.
inequality_constraints (Optional[List[Tuple[torch.Tensor, torch.Tensor, float]]]) –
device (Optional[torch.device]) –
dtype (Optional[torch.dtype]) –
- Returns
- Estimated proportion of volume in feature space that is
feasible wrt the bounds and the inequality constraints (linear).
- Estimated proportion of feasible features for which
posterior samples (outcome) satisfies the outcome constraints with probability above the given threshold.
- Return type
2-element tuple containing
Multi-Objective Utilities¶
Abstract Box Decompositions¶
Box decomposition algorithms.
References
- Lacour17(1,2,3,4,5,6)
R. Lacour, K. Klamroth, C. Fonseca. A box decomposition algorithm to compute the hypervolume indicator. Computers & Operations Research, Volume 79, 2017.
- class botorch.utils.multi_objective.box_decompositions.box_decomposition.BoxDecomposition(ref_point, sort, Y=None)[source]¶
Bases:
torch.nn.modules.module.Module
,abc.ABC
An abstract class for box decompositions.
Note: Internally, we store the negative reference point (minimization).
Initialize BoxDecomposition.
- Parameters
ref_point (Tensor) – A m-dim tensor containing the reference point.
sort (bool) – A boolean indicating whether to sort the Pareto frontier.
Y (Optional[Tensor]) – A (batch_shape) x n x m-dim tensor of outcomes.
- Return type
None
- property pareto_Y: torch.Tensor¶
This returns the non-dominated set.
- Returns
A n_pareto x m-dim tensor of outcomes.
- property ref_point: torch.Tensor¶
Get the reference point.
- Returns
A m-dim tensor of outcomes.
- property Y: torch.Tensor¶
Get the raw outcomes.
- Returns
A n x m-dim tensor of outcomes.
- abstract get_hypercell_bounds()[source]¶
Get the bounds of each hypercell in the decomposition.
- Returns
- A 2 x num_cells x num_outcomes-dim tensor containing the
lower and upper vertices bounding each hypercell.
- Return type
torch.Tensor
- update(Y)[source]¶
Update non-dominated front and decomposition.
By default, the partitioning is recomputed. Subclasses can override this functionality.
- Parameters
Y (torch.Tensor) – A (batch_shape) x n x m-dim tensor of new, incremental outcomes.
- Return type
None
- abstract compute_hypervolume()[source]¶
Compute hypervolume that is dominated by the Pareto Froniter.
- Returns
- A (batch_shape)-dim tensor containing the hypervolume dominated by
each Pareto frontier.
- Return type
torch.Tensor
- training: bool¶
- class botorch.utils.multi_objective.box_decompositions.box_decomposition.FastPartitioning(ref_point, Y=None)[source]¶
Bases:
botorch.utils.multi_objective.box_decompositions.box_decomposition.BoxDecomposition
,abc.ABC
A class for partitioning the (non-)dominated space into hyper-cells.
Note: this assumes maximization. Internally, it multiplies outcomes by -1 and performs the decomposition under minimization.
This class is abstract to support to two applications of Alg 1 from [Lacour17]: 1) partitioning the space that is dominated by the Pareto frontier and 2) partitioning the space that is not dominated by the Pareto frontier.
Initialize FastPartitioning.
- Parameters
ref_point (Tensor) – A m-dim tensor containing the reference point.
Y (Optional[Tensor]) – A (batch_shape) x n x m-dim tensor
- Return type
None
- update(Y)[source]¶
Update non-dominated front and decomposition.
- Parameters
Y (torch.Tensor) – A (batch_shape) x n x m-dim tensor of new, incremental outcomes.
- Return type
None
- get_hypercell_bounds()[source]¶
Get the bounds of each hypercell in the decomposition.
- Returns
- A 2 x (batch_shape) x num_cells x m-dim tensor containing the
lower and upper vertices bounding each hypercell.
- Return type
torch.Tensor
- training: bool¶
Box Decomposition List¶
Box decomposition container.
- class botorch.utils.multi_objective.box_decompositions.box_decomposition_list.BoxDecompositionList(*box_decompositions)[source]¶
Bases:
torch.nn.modules.module.Module
A list of box decompositions.
Initialize the box decomposition list.
- Parameters
*box_decompositions – An variable number of box decompositions
box_decompositions (BoxDecomposition) –
- Return type
None
Example
>>> bd1 = FastNondominatedPartitioning(ref_point, Y=Y1) >>> bd2 = FastNondominatedPartitioning(ref_point, Y=Y2) >>> bd = BoxDecompositionList(bd1, bd2)
- property pareto_Y: List[torch.Tensor]¶
This returns the non-dominated set.
Note: Internally, we store the negative pareto set (minimization).
- Returns
- A list where the ith element is the n_pareto_i x m-dim tensor
of pareto optimal outcomes for each box_decomposition i.
- property ref_point: torch.Tensor¶
Get the reference point.
Note: Internally, we store the negative reference point (minimization).
- Returns
A n_box_decompositions x m-dim tensor of outcomes.
- get_hypercell_bounds()[source]¶
Get the bounds of each hypercell in the decomposition.
- Returns
- A 2 x n_box_decompositions x num_cells x num_outcomes-dim tensor
containing the lower and upper vertices bounding each hypercell.
- Return type
torch.Tensor
- update(Y)[source]¶
Update the partitioning.
- Parameters
Y (Union[List[torch.Tensor], torch.Tensor]) – A n_box_decompositions x n x num_outcomes-dim tensor or a list where the ith element contains the new points for box_decomposition i.
- Return type
None
- compute_hypervolume()[source]¶
Compute hypervolume that is dominated by the Pareto Froniter.
- Returns
- A (batch_shape)-dim tensor containing the hypervolume dominated by
each Pareto frontier.
- Return type
torch.Tensor
- training: bool¶
Box Decomposition Utilities¶
Utilities for box decomposition algorithms.
- botorch.utils.multi_objective.box_decompositions.utils.compute_local_upper_bounds(U, Z, z)[source]¶
Compute local upper bounds.
Note: this assumes minimization.
This uses the incremental algorithm (Alg. 1) from [Lacour17].
- Parameters
U (torch.Tensor) – A n x m-dim tensor containing the local upper bounds.
Z (torch.Tensor) – A n x m x m-dim tensor containing the defining points.
z (torch.Tensor) – A m-dim tensor containing the new point.
- Returns
A new n’ x m-dim tensor local upper bounds.
A n’ x m x m-dim tensor containing the defining points.
- Return type
2-element tuple containing
- botorch.utils.multi_objective.box_decompositions.utils.get_partition_bounds(Z, U, ref_point)[source]¶
Get the cell bounds given the local upper bounds and the defining points.
This implements Equation 2 in [Lacour17].
- Parameters
Z (torch.Tensor) – A n x m x m-dim tensor containing the defining points. The first dimension corresponds to u_idx, the second dimension corresponds to j, and Z[u_idx, j] is the set of definining points Z^j(u) where u = U[u_idx].
U (torch.Tensor) – A n x m-dim tensor containing the local upper bounds.
ref_point (torch.Tensor) – A m-dim tensor containing the reference point.
- Returns
- A 2 x num_cells x m-dim tensor containing the lower and upper vertices
bounding each hypercell.
- Return type
torch.Tensor
- botorch.utils.multi_objective.box_decompositions.utils.update_local_upper_bounds_incremental(new_pareto_Y, U, Z)[source]¶
Update the current local upper with the new pareto points.
This assumes minimization.
- Parameters
new_pareto_Y (torch.Tensor) – A n x m-dim tensor containing the new Pareto points.
U (torch.Tensor) – A n’ x m-dim tensor containing the local upper bounds.
Z (torch.Tensor) – A n x m x m-dim tensor containing the defining points.
- Returns
A new n’ x m-dim tensor local upper bounds.
A n’ x m x m-dim tensor containing the defining points
- Return type
2-element tuple containing
- botorch.utils.multi_objective.box_decompositions.utils.compute_non_dominated_hypercell_bounds_2d(pareto_Y_sorted, ref_point)[source]¶
Compute an axis-aligned partitioning of the non-dominated space for 2 objectives.
- Parameters
pareto_Y_sorted (torch.Tensor) – A (batch_shape) x n_pareto x 2-dim tensor of pareto outcomes that are sorted by the 0th dimension in increasing order. All points must be better than the reference point.
ref_point (torch.Tensor) – A (batch_shape) x 2-dim reference point.
- Returns
A 2 x (batch_shape) x n_pareto + 1 x m-dim tensor of cell bounds.
- Return type
torch.Tensor
- botorch.utils.multi_objective.box_decompositions.utils.compute_dominated_hypercell_bounds_2d(pareto_Y_sorted, ref_point)[source]¶
Compute an axis-aligned partitioning of the dominated space for 2-objectives.
- Parameters
pareto_Y_sorted (torch.Tensor) – A (batch_shape) x n_pareto x 2-dim tensor of pareto outcomes that are sorted by the 0th dimension in increasing order.
ref_point (torch.Tensor) – A 2-dim reference point.
- Returns
A 2 x (batch_shape) x n_pareto x m-dim tensor of cell bounds.
- Return type
torch.Tensor
Box Decompositions [DEPRECATED - use botorch..utils.multi_objective.box_decompositions]¶
DEPRECATED - Box decomposition algorithms. Use the botorch.utils.multi_objective.box_decompositions instead.
Dominated Partitionings¶
Algorithms for partitioning the dominated space into hyperrectangles.
- class botorch.utils.multi_objective.box_decompositions.dominated.DominatedPartitioning(ref_point, Y=None)[source]¶
Bases:
botorch.utils.multi_objective.box_decompositions.box_decomposition.FastPartitioning
Partition dominated space into axis-aligned hyperrectangles.
This uses the Algorithm 1 from [Lacour17].
Example
>>> bd = DominatedPartitioning(ref_point, Y)
Initialize FastPartitioning.
- Parameters
ref_point (Tensor) – A m-dim tensor containing the reference point.
Y (Optional[Tensor]) – A (batch_shape) x n x m-dim tensor
- Return type
None
- compute_hypervolume()[source]¶
Compute hypervolume that is dominated by the Pareto Frontier.
- Returns
- A (batch_shape)-dim tensor containing the hypervolume dominated by
each Pareto frontier.
- Return type
torch.Tensor
- training: bool¶
Hypervolume¶
Hypervolume Utilities.
References
- Fonseca2006(1,2)
C. M. Fonseca, L. Paquete, and M. Lopez-Ibanez. An improved dimension-sweep algorithm for the hypervolume indicator. In IEEE Congress on Evolutionary Computation, pages 1157-1163, Vancouver, Canada, July 2006.
- Ishibuchi2011
H. Ishibuchi, N. Akedo, and Y. Nojima. A many-objective test problem for visually examining diversity maintenance behavior in a decision space. Proc. 13th Annual Conf. Genetic Evol. Comput., 2011.
- botorch.utils.multi_objective.hypervolume.infer_reference_point(pareto_Y, max_ref_point=None, scale=0.1, scale_max_ref_point=False)[source]¶
Get reference point for hypervolume computations.
This sets the reference point to be ref_point = nadir - 0.1 * range when there is no pareto_Y that is better than the reference point.
[Ishibuchi2011] find 0.1 to be a robust multiplier for scaling the nadir point.
Note: this assumes maximization of all objectives.
- Parameters
pareto_Y (torch.Tensor) – A n x m-dim tensor of Pareto-optimal points.
max_ref_point (Optional[torch.Tensor]) – A m dim tensor indicating the maximum reference point.
scale (float) – A multiplier used to scale back the reference point based on the range of each objective.
scale_max_ref_point (bool) – A boolean indicating whether to apply scaling to the max_ref_point based on the range of each objective.
- Returns
A m-dim tensor containing the reference point.
- Return type
torch.Tensor
- class botorch.utils.multi_objective.hypervolume.Hypervolume(ref_point)[source]¶
Bases:
object
Hypervolume computation dimension sweep algorithm from [Fonseca2006].
Adapted from Simon Wessing’s implementation of the algorithm (Variant 3, Version 1.2) in [Fonseca2006] in PyMOO: https://github.com/msu-coinlab/pymoo/blob/master/pymoo/vendor/hv.py
Maximization is assumed.
TODO: write this in C++ for faster looping.
Initialize hypervolume object.
- Parameters
ref_point (Tensor) – m-dim Tensor containing the reference point.
- Return type
None
- property ref_point: torch.Tensor¶
Get reference point (for maximization).
- Returns
A m-dim tensor containing the reference point.
- botorch.utils.multi_objective.hypervolume.sort_by_dimension(nodes, i)[source]¶
Sorts the list of nodes in-place by the specified objective.
- Parameters
nodes (List[botorch.utils.multi_objective.hypervolume.Node]) – A list of Nodes
i (int) – The index of the objective to sort by
- Return type
None
- class botorch.utils.multi_objective.hypervolume.Node(m, dtype, device, data=None)[source]¶
Bases:
object
Node in the MultiList data structure.
Initialize MultiList.
- Parameters
m (int) – The number of objectives
dtype (torch.dtype) – The dtype
device (torch.device) – The device
data (Optional[Tensor]) – The tensor data to be stored in this Node.
- Return type
None
- class botorch.utils.multi_objective.hypervolume.MultiList(m, dtype, device)[source]¶
Bases:
object
A special data structure used in hypervolume computation.
It consists of several doubly linked lists that share common nodes. Every node has multiple predecessors and successors, one in every list.
Initialize m doubly linked lists.
- Parameters
m (int) – number of doubly linked lists
dtype (torch.dtype) – the dtype
device (torch.device) – the device
- Return type
None
- append(node, index)[source]¶
Appends a node to the end of the list at the given index.
- Parameters
node (botorch.utils.multi_objective.hypervolume.Node) – the new node
index (int) – the index where the node should be appended.
- Return type
None
- extend(nodes, index)[source]¶
Extends the list at the given index with the nodes.
- Parameters
nodes (List[botorch.utils.multi_objective.hypervolume.Node]) – list of nodes to append at the given index.
index (int) – the index where the nodes should be appended.
- Return type
None
- remove(node, index, bounds)[source]¶
Removes and returns ‘node’ from all lists in [0, ‘index’].
- Parameters
node (botorch.utils.multi_objective.hypervolume.Node) – The node to remove
index (int) – The upper bound on the range of indices
bounds (torch.Tensor) – A 2 x m-dim tensor bounds on the objectives
- Return type
- reinsert(node, index, bounds)[source]¶
Re-inserts the node at its original position.
Re-inserts the node at its original position in all lists in [0, ‘index’] before it was removed. This method assumes that the next and previous nodes of the node that is reinserted are in the list.
- Parameters
node (botorch.utils.multi_objective.hypervolume.Node) – The node
index (int) – The upper bound on the range of indices
bounds (torch.Tensor) – A 2 x m-dim tensor bounds on the objectives
- Return type
None
Non-dominated Partitionings¶
Algorithms for partitioning the non-dominated space into rectangles.
References
- Couckuyt2012(1,2)
I. Couckuyt, D. Deschrijver and T. Dhaene, “Towards Efficient Multiobjective Optimization: Multiobjective statistical criterions,” 2012 IEEE Congress on Evolutionary Computation, Brisbane, QLD, 2012, pp. 1-8.
- class botorch.utils.multi_objective.box_decompositions.non_dominated.NondominatedPartitioning(ref_point, Y=None, alpha=0.0)[source]¶
Bases:
botorch.utils.multi_objective.box_decompositions.box_decomposition.BoxDecomposition
A class for partitioning the non-dominated space into hyper-cells.
Note: this assumes maximization. Internally, it multiplies outcomes by -1 and performs the decomposition under minimization. TODO: use maximization internally as well.
Note: it is only feasible to use this algorithm to compute an exact decomposition of the non-dominated space for m<5 objectives (alpha=0.0).
The alpha parameter can be increased to obtain an approximate partitioning faster. The alpha is a fraction of the total hypervolume encapsuling the entire Pareto set. When a hypercell’s volume divided by the total hypervolume is less than alpha, we discard the hypercell. See Figure 2 in [Couckuyt2012] for a visual representation.
This PyTorch implementation of the binary partitioning algorithm ([Couckuyt2012]) is adapted from numpy/tensorflow implementation at: https://github.com/GPflow/GPflowOpt/blob/master/gpflowopt/pareto.py.
TODO: replace this with a more efficient decomposition. E.g. https://link.springer.com/content/pdf/10.1007/s10898-019-00798-7.pdf
Initialize NondominatedPartitioning.
- Parameters
ref_point (Tensor) – A m-dim tensor containing the reference point.
Y (Optional[Tensor]) – A (batch_shape) x n x m-dim tensor.
alpha (float) – A thresold fraction of total volume used in an approximate decomposition.
- Return type
None
Example
>>> bd = NondominatedPartitioning(ref_point, Y=Y1)
- get_hypercell_bounds()[source]¶
Get the bounds of each hypercell in the decomposition.
- Parameters
ref_point – A (batch_shape) x m-dim tensor containing the reference point.
- Returns
- A 2 x num_cells x m-dim tensor containing the
lower and upper vertices bounding each hypercell.
- Return type
torch.Tensor
- compute_hypervolume()[source]¶
Compute the hypervolume for the given reference point.
This method computes the hypervolume of the non-dominated space and computes the difference between the hypervolume between the ideal point and hypervolume of the non-dominated space.
- Returns
(batch_shape)-dim tensor containing the dominated hypervolume.
- Return type
torch.Tensor
- training: bool¶
- class botorch.utils.multi_objective.box_decompositions.non_dominated.FastNondominatedPartitioning(ref_point, Y=None)[source]¶
Bases:
botorch.utils.multi_objective.box_decompositions.box_decomposition.FastPartitioning
A class for partitioning the non-dominated space into hyper-cells.
Note: this assumes maximization. Internally, it multiplies by -1 and performs the decomposition under minimization.
This class is far more efficient than NondominatedPartitioning for exact box partitionings
- This class uses the two-step approach similar to that in [Yang2019], where:
- first, Alg 1 from [Lacour17] is used to find the local lower bounds
for the maximization problem
- second, the local lower bounds are used as the Pareto frontier for the
minimization problem, and [Lacour17] is applied again to partition the space dominated by that Pareto frontier.
Initialize FastNondominatedPartitioning.
- Parameters
ref_point (Tensor) – A m-dim tensor containing the reference point.
Y (Optional[Tensor]) – A (batch_shape) x n x m-dim tensor.
- Return type
None
Example
>>> bd = FastNondominatedPartitioning(ref_point, Y=Y1)
- compute_hypervolume()[source]¶
Compute hypervolume that is dominated by the Pareto Froniter.
- Returns
- A (batch_shape)-dim tensor containing the hypervolume dominated by
each Pareto frontier.
- training: bool¶
Pareto¶
- botorch.utils.multi_objective.pareto.is_non_dominated(Y, deduplicate=True)[source]¶
Computes the non-dominated front.
Note: this assumes maximization.
For small n, this method uses a highly parallel methodology that compares all pairs of points in Y. However, this is memory intensive and slow for large n. For large n (or if Y is larger than 5MB), this method will dispatch to a loop-based approach that is faster and has a lower memory footprint.
- Parameters
Y (torch.Tensor) – A (batch_shape) x n x m-dim tensor of outcomes.
deduplicate (bool) – A boolean indicating whether to only return unique points on the pareto frontier.
- Returns
A (batch_shape) x n-dim boolean tensor indicating whether each point is non-dominated.
- Return type
torch.Tensor
Scalarization¶
Helper utilities for constructing scalarizations.
References
- Knowles2005(1,2)
J. Knowles, “ParEGO: a hybrid algorithm with on-line landscape approximation for expensive multiobjective optimization problems,” in IEEE Transactions on Evolutionary Computation, vol. 10, no. 1, pp. 50-66, Feb. 2006.
- botorch.utils.multi_objective.scalarization.get_chebyshev_scalarization(weights, Y, alpha=0.05)[source]¶
Construct an augmented Chebyshev scalarization.
Outcomes are first normalized to [0,1] and then an augmented Chebyshev scalarization is applied.
- Augmented Chebyshev scalarization:
objective(y) = min(w * y) + alpha * sum(w * y)
Note: this assumes maximization.
See [Knowles2005] for details.
This scalarization can be used with qExpectedImprovement to implement q-ParEGO as proposed in [Daulton2020qehvi].
- Parameters
weights (torch.Tensor) – A m-dim tensor of weights.
Y (torch.Tensor) – A n x m-dim tensor of observed outcomes, which are used for scaling the outcomes to [0,1].
alpha (float) – Parameter governing the influence of the weighted sum term. The default value comes from [Knowles2005].
- Returns
Transform function using the objective weights.
- Return type
Callable[[torch.Tensor, Optional[torch.Tensor]], torch.Tensor]
Example
>>> weights = torch.tensor([0.75, 0.25]) >>> transform = get_aug_chebyshev_scalarization(weights, Y)