bugfix

chiron/mcmc.py

@@ -308,6 +308,8 @@ def run(self, n_iterations: int = 1):
                 log.info(f"Performing: {move_name}")
                 move.run(self.sampler_state, self.thermodynamic_state)
 
+        log.info("Finished running Gibbs sampler")
+
 
 class MetropolizedMove(MCMove):
     """A base class for metropolized moves.
@@ -368,26 +370,25 @@ def apply(self, thermodynamic_state, sampler_state):
 
         # Compute initial energy
         initial_energy = thermodynamic_state.get_reduced_potential(sampler_state)
+        log.debug(f"Initial energy is {initial_energy}.")
         # Store initial positions of the atoms that are moved.
         # We'll use this also to recover in case the move is rejected.
         atom_subset = self.atom_subset
-        if isinstance(atom_subset, slice):
-            # Numpy array when sliced return a view, they are not copied.
-            initial_positions = copy.deepcopy(sampler_state.x0[atom_subset])
-        else:
-            # This automatically creates a copy.
-            initial_positions = sampler_state.x0[atom_subset]
-
+        log.debug(f"Atom subset is {atom_subset}.")
+        initial_positions = copy.deepcopy(sampler_state.x0[atom_subset])
+        log.debug(f"Initial positions are {initial_positions}.")
         # Propose perturbed positions. Modifying the reference changes the sampler state.
         proposed_positions = self._propose_positions(initial_positions)
+        log.debug(f"Proposed positions are {proposed_positions}.")
+        log.debug(f"Sampler state is {sampler_state.x0}.")
 
         # Compute the energy of the proposed positions.
         sampler_state.x0[atom_subset] = proposed_positions
-
         proposed_energy = thermodynamic_state.get_reduced_potential(sampler_state)
-
+        log.debug(f"Proposed energy is {proposed_energy}.")
         # Accept or reject with Metropolis criteria.
         delta_energy = proposed_energy - initial_energy
+        log.debug(f"Delta energy is {delta_energy}.")
         import jax.random as jrandom
 
         key, subkey = jrandom.split(self.key)
@@ -396,9 +397,15 @@ def apply(self, thermodynamic_state, sampler_state):
             delta_energy <= 0.0 or jrandom.normal(subkey) < jnp.exp(-delta_energy)
         ):
             self.n_accepted += 1
+            log.debug(
+                f"Move accepted. Energy change: {delta_energy:.3f}. Number of accepted moves: {self.n_accepted}."
+            )
         else:
             # Restore original positions.
             sampler_state.x0[atom_subset] = initial_positions
+            log.debug(
+                f"Move rejected. Energy change: {delta_energy:.3f}. Number of rejected moves: {self.n_proposed - self.n_accepted}."
+            )
         self.n_proposed += 1
 
     def _propose_positions(self, positions: jnp.ndarray):
@@ -455,9 +462,11 @@ def __init__(
         seed: int = 1234,
         displacement_sigma=1.0 * unit.nanometer,
         nr_of_moves: int = 100,
+        atom_subset: Optional[List[int]] = None,
     ):
         super().__init__(nr_of_moves=nr_of_moves, seed=seed)
         self.displacement_sigma = displacement_sigma
+        self.atom_subset = atom_subset
 
     def displace_positions(self, positions, displacement_sigma=1.0 * unit.nanometer):
         """Return the positions after applying a random displacement to them.
@@ -492,4 +501,6 @@ def _propose_positions(self, initial_positions):
         return self.displace_positions(initial_positions, self.displacement_sigma)
 
     def run(self, sampler_state, thermodynamic_state):
-        self.apply(thermodynamic_state, sampler_state)
+        for trials in range(self.nr_of_moves):
+            self.apply(thermodynamic_state, sampler_state)
+            log.info(f"Acceptance rate: {self.n_accepted / self.n_proposed}")

chiron/tests/test_mcmc.py

@@ -116,8 +116,15 @@ def test_sample_from_harmonic_osciallator_with_MCMC_classes_and_MetropolisDispla
     )
     sampler_state = SamplerState(ho.positions)
 
+    from functools import partial
+    from chiron.utils import slice_array
+
     # Initalize the move set (here only LangevinDynamicsMove)
-    mc_displacement_move = MetropolisDisplacementMove(nr_of_moves=100)
+    mc_displacement_move = MetropolisDisplacementMove(
+        nr_of_moves=10,
+        displacement_sigma=0.1 * unit.angstrom,
+        atom_subset=[0],
+    )
 
     move_set = MoveSet([("MetropolisDisplacementMove", mc_displacement_move)])
 

chiron/tests/test_testsystems.py

@@ -1,4 +1,11 @@
 def test_HO():
+    """
+    Test the harmonic oscillator system using a Langevin integrator.
+
+    This function initializes a harmonic oscillator from openmmtools.testsystems,
+    sets up a harmonic potential, and uses the Langevin integrator to run the simulation.
+    It then tests if the standard deviation of the potential is close to the expected value.
+    """
     from openmm.unit import kelvin
 
     # initialize testystem