AmiciObjective/PEtab import: Fix plist

For further background, see #1448.

We don't have to compute the full gradient in every model simulation. Some entries might not be required because of fixed parameter or some condition-specific objective parameter mapping. The former was supported (however, not tested), the latter was not supported. Now both are tested an supported.

There was no good way to communicate the fixed parameters to AmiciCalculator where ExpData.plist gets set. Passing this information is currently only possible through the parameter mapping, based on which the required sensitivities are determined. Therefore, in addition to the general parameter mapping, there is now a parameter mapping that accounts for the fixed parameters. Not sure what could be a more elegant way to handle that.

pypesto/objective/amici/amici.py

@@ -178,8 +178,12 @@ def __init__(
             parameter_mapping = create_identity_parameter_mapping(
                 amici_model, len(edatas)
             )
+        # parameter mapping where IDs of the currently fixed parameters
+        #  have been replaced by their respective values
+        #  (relevant for setting ``plist`` in ExpData later on)
         self.parameter_mapping = parameter_mapping
-
+        # parameter mapping independent of fixed parameters
+        self._parameter_mapping_full = copy.deepcopy(parameter_mapping)
         # If supported, enable `guess_steadystate` by default. If not
         #  supported, disable by default. If requested but unsupported, raise.
         if (
@@ -654,3 +658,38 @@ def check_gradients_match_finite_differences(
         return super().check_gradients_match_finite_differences(
             *args, x=x, x_free=x_free, **kwargs
         )
+
+    def update_from_problem(
+        self,
+        dim_full: int,
+        x_free_indices: Sequence[int],
+        x_fixed_indices: Sequence[int],
+        x_fixed_vals: Sequence[float],
+    ):
+        """Handle fixed parameters."""
+        super().update_from_problem(
+            dim_full=dim_full,
+            x_free_indices=x_free_indices,
+            x_fixed_indices=x_fixed_indices,
+            x_fixed_vals=x_fixed_vals,
+        )
+
+        # To make amici aware of fixed parameters, and thus, avoid computing
+        #  unnecessary sensitivities, we need to update the parameter mapping
+        #  and replace the IDs of all fixed parameters by their respective
+        #  values.
+        self.parameter_mapping = copy.deepcopy(self._parameter_mapping_full)
+        if not len(x_fixed_indices):
+            return
+
+        id_to_val = {
+            self.x_ids[x_idx]: x_val
+            for x_idx, x_val in zip(x_fixed_indices, x_fixed_vals)
+        }
+        for condition_mapping in self.parameter_mapping:
+            for (
+                model_par,
+                mapped_to_par,
+            ) in condition_mapping.map_sim_var.items():
+                if (val := id_to_val.get(mapped_to_par)) is not None:
+                    condition_mapping.map_sim_var[model_par] = val

test/petab/test_petab_import.py

@@ -5,6 +5,7 @@
 import logging
 import os
 import unittest
+from itertools import chain
 
 import amici
 import benchmark_models_petab as models
@@ -18,8 +19,6 @@
 import pypesto.petab
 from pypesto.petab import PetabImporter
 
-from .test_sbml_conversion import ATOL, RTOL
-
 # In CI, bionetgen is installed here
 BNGPATH = os.path.abspath(
     os.path.join(os.path.dirname(__file__), "..", "..", "BioNetGen-2.8.5")
@@ -119,7 +118,7 @@ def test_check_gradients(self):
         # Check gradients of simple model (should always be a true positive)
         model_name = "Boehm_JProteomeRes2014"
         importer = pypesto.petab.PetabImporter.from_yaml(
-            os.path.join(models.MODELS_DIR, model_name, model_name + ".yaml")
+            models.get_problem_yaml_path(model_name)
         )
 
         objective = importer.create_problem().objective
@@ -137,35 +136,76 @@ def test_check_gradients(self):
 
 
 def test_plist_mapping():
-    """Test that the AMICI objective created via PEtab correctly maps
-    gradient entries when some parameters are not estimated (realized via
-    edata.plist)."""
-    model_name = "Boehm_JProteomeRes2014"
-    petab_problem = pypesto.petab.PetabImporter.from_yaml(
+    """Test that the AMICI objective created via PEtab correctly uses
+    ExpData.plist.
+
+    That means, ensure that
+    1) it only computes gradient entries that are really required, and
+    2) correctly maps model-gradient entries to the objective gradient
+    3) with or without pypesto-fixed parameters.
+
+    In Bruno_JExpBot2016, different parameters are estimated in different
+    conditions.
+    """
+    model_name = "Bruno_JExpBot2016"
+    petab_importer = pypesto.petab.PetabImporter.from_yaml(
         os.path.join(models.MODELS_DIR, model_name, model_name + ".yaml")
     )
-
-    # define test parameter
-    par = np.asarray(petab_problem.petab_problem.x_nominal_scaled)
-
-    problem = petab_problem.create_problem()
+    objective_creator = petab_importer.create_objective_creator()
+    problem = petab_importer.create_problem(
+        objective_creator.create_objective()
+    )
     objective = problem.objective
-    # check that x_names are correctly subsetted
-    assert objective.x_names == [
-        problem.x_names[ix] for ix in problem.x_free_indices
-    ]
     objective.amici_solver.setSensitivityMethod(
-        amici.SensitivityMethod_forward
+        amici.SensitivityMethod.forward
     )
-    objective.amici_solver.setAbsoluteTolerance(1e-10)
-    objective.amici_solver.setRelativeTolerance(1e-12)
+    objective.amici_solver.setAbsoluteTolerance(1e-16)
+    objective.amici_solver.setRelativeTolerance(1e-15)
+
+    # slightly perturb the parameters to avoid vanishing gradients
+    par = np.asarray(petab_importer.petab_problem.x_nominal_free_scaled) * 1.01
+
+    # call once to make sure ExpDatas are populated
+    fx1, grad1 = objective(par, sensi_orders=(0, 1))
+
+    plists1 = {edata.plist for edata in objective.edatas}
+    assert len(plists1) == 6, plists1
 
     df = objective.check_grad_multi_eps(
-        par[problem.x_free_indices], multi_eps=[1e-3, 1e-4, 1e-5]
+        par[problem.x_free_indices], multi_eps=[1e-5, 1e-6, 1e-7, 1e-8]
     )
     print("relative errors gradient: ", df.rel_err.values)
     print("absolute errors gradient: ", df.abs_err.values)
-    assert np.all((df.rel_err.values < RTOL) | (df.abs_err.values < ATOL))
+    assert np.all((df.rel_err.values < 1e-8) | (df.abs_err.values < 1e-10))
+
+    # do the same after fixing some parameters
+    # we fix them to the previous values, so we can compare the results
+    fixed_ids = ["init_b10_1", "init_bcry_1"]
+    # the corresponding amici parameters (they are only ever mapped to the
+    #  respective parameters in fixed_ids, and thus, should not occur in any
+    #  `plist` later on)
+    fixed_model_par_ids = ["init_b10", "init_bcry"]
+    fixed_model_par_idxs = [
+        objective.amici_model.getParameterIds().index(id)
+        for id in fixed_model_par_ids
+    ]
+    fixed_idxs = [problem.x_names.index(id) for id in fixed_ids]
+    problem.fix_parameters(fixed_idxs, par[fixed_idxs])
+    assert objective is problem.objective
+    assert problem.x_fixed_indices == fixed_idxs
+    fx2, grad2 = objective(par[problem.x_free_indices], sensi_orders=(0, 1))
+    assert np.isclose(fx1, fx2, rtol=1e-10, atol=1e-14)
+    assert np.allclose(
+        grad1[problem.x_free_indices], grad2, rtol=1e-10, atol=1e-14
+    )
+    plists2 = {edata.plist for edata in objective.edatas}
+    # the fixed parameters should have been in plist1, but not in plist2
+    assert (
+        set(fixed_model_par_idxs) - set(chain.from_iterable(plists1)) == set()
+    )
+    assert (
+        set(fixed_model_par_idxs) & set(chain.from_iterable(plists2)) == set()
+    )
 
 
 def test_max_sensi_order():