Undo dependency on botorch master

Summary:
Ax released a version that depended on changes on botorch master: #159

This changes things back so it should work with botorch 0.1.3.

Reviewed By: lena-kashtelyan

Differential Revision: D17093727

fbshipit-source-id: 7d08d4205743c8135fb4adde73befa45a0204816

Author: Balandat

ax/models/tests/test_botorch_model.py

@@ -148,14 +148,11 @@ def test_BotorchModel(self, dtype=torch.float, cuda=False):
         n = 3
 
         X_dummy = torch.tensor([[[1.0, 2.0, 3.0]]], dtype=dtype, device=device)
-        acq_dummy = torch.tensor(0.0, dtype=dtype, device=device)
         model_gen_options = {}
         # test sequential optimize
         with mock.patch(
-            "ax.models.torch.botorch_defaults.optimize_acqf",
-            return_value=(X_dummy, acq_dummy),
+            "ax.models.torch.botorch_defaults.sequential_optimize", return_value=X_dummy
         ) as mock_optimize_acqf:
-
             Xgen, wgen = model.gen(
                 n=n,
                 bounds=bounds,
@@ -173,8 +170,7 @@ def test_BotorchModel(self, dtype=torch.float, cuda=False):
 
         # test joint optimize
         with mock.patch(
-            "ax.models.torch.botorch_defaults.optimize_acqf",
-            return_value=(X_dummy, acq_dummy),
+            "ax.models.torch.botorch_defaults.joint_optimize", return_value=X_dummy
         ) as mock_optimize_acqf:
             Xgen, wgen = model.gen(
                 n=n,

ax/models/torch/botorch.py

@@ -55,7 +55,7 @@
         Optional[Callable[[Tensor], Tensor]],
         Any,
     ],
-    Tuple[Tensor, Tensor],
+    Tensor,
 ]
 
 
@@ -146,16 +146,15 @@ class BotorchModel(TorchModel):
             fixed_features,
             rounding_func,
             **kwargs,
-        ) -> (candidates, acq_values)
+        ) -> candidates
 
     Here `acq_function` is a BoTorch `AcquisitionFunction`, `bounds` is a
     tensor containing bounds on the parameters, `n` is the number of
     candidates to be generated, `inequality_constraints` are inequality
     constraints on parameter values, `fixed_features` specifies features that
     should be fixed during generation, and `rounding_func` is a callback
     that rounds an optimization result appropriately. `candidates` is
-    a tensor of generated candidates, and `acq_values` are the acquisition
-    values associated with the candidates. For additional details on the
+    a tensor of generated candidates. For additional details on the
     arguments, see `scipy_optimizer`.
     """
 
@@ -316,7 +315,7 @@ def gen(
 
         botorch_rounding_func = get_rounding_func(rounding_func)
 
-        candidates, _ = self.acqf_optimizer(  # pyre-ignore: [28]
+        candidates = self.acqf_optimizer(  # pyre-ignore: [28]
             acq_function=checked_cast(AcquisitionFunction, acquisition_function),
             bounds=bounds_,
             n=n,

ax/models/torch/botorch_defaults.py

@@ -18,7 +18,7 @@
 from botorch.models.model import Model
 from botorch.models.model_list_gp_regression import ModelListGP
 from botorch.models.multitask import FixedNoiseMultiTaskGP, MultiTaskGP
-from botorch.optim.optimize import optimize_acqf
+from botorch.optim.optimize import joint_optimize, sequential_optimize
 from botorch.utils import (
     get_objective_weights_transform,
     get_outcome_constraint_transforms,
@@ -204,7 +204,7 @@ def scipy_optimizer(
     fixed_features: Optional[Dict[int, float]] = None,
     rounding_func: Optional[Callable[[Tensor], Tensor]] = None,
     **kwargs: Any,
-) -> Tuple[Tensor, Tensor]:
+) -> Tensor:
     r"""Optimizer using scipy's minimize module on a numpy-adpator.
 
     Args:
@@ -233,12 +233,15 @@ def scipy_optimizer(
     num_restarts: int = kwargs.get("num_restarts", 20)
     raw_samples: int = kwargs.get("num_raw_samples", 50 * num_restarts)
 
-    sequential = not kwargs.get("joint_optimization", False)
-    # use SLSQP by default for small problems since it yields faster wall times
-    if sequential and "method" not in kwargs:
-        kwargs["method"] = "SLSQP"
+    if kwargs.get("joint_optimization", False):
+        optimize = joint_optimize
+    else:
+        optimize = sequential_optimize
+        # use SLSQP by default for small problems since it yields faster wall times
+        if "method" not in kwargs:
+            kwargs["method"] = "SLSQP"
 
-    return optimize_acqf(
+    X = optimize(
         acq_function=acq_function,
         bounds=bounds,
         q=n,
@@ -248,8 +251,11 @@ def scipy_optimizer(
         inequality_constraints=inequality_constraints,
         fixed_features=fixed_features,
         post_processing_func=rounding_func,
-        sequential=not kwargs.get("joint_optimization", False),
     )
+    # TODO: Un-hack this once botorch #234 is part of a stable release
+    if isinstance(X, tuple):
+        X, _ = X
+    return X
 
 
 def _get_model(