Improve Checkpointing

docs/simulations.rst

@@ -55,6 +55,9 @@ Here is the help message of :code:`run_REXEE`:
                               whole-range alchemical weights. This file is a necessary input
                               if one wants to update the file when extending a weight-
                               updating simulation. (Default: g_vecs.npy)
+      -e EQUIL, --equil EQUIL
+                              The file path of the NPY file containing the equilibration times for all simulations
+                              when completing a variable weight REXEE simulation. (Default: equil.npy)
       -o OUTPUT, --output OUTPUT
                               The file path of the output file for logging how replicas
                               interact with each other. (Default: run_REXEE_log.txt)
@@ -139,6 +142,7 @@ two files (generated by the existing simulation) as necessary checkpoints:
 
 * One NPY file containing the replica-space trajectories of different configurations, as specified in the input YAML file.
 * One NPY file containing the time series of the whole-range alchemical weights, as specified in the input YAML file. This is only needed for extending a weight-updating REXEE simulation.
+* One NPY file containing the equilibration times for all simulations or -1 if the simulation is not yet equilibrated. This is only needed if extending a weight-updating REXEE simulation.
 
 In the CLI :code:`run_REXEE`, the class :class:`.ReplicaExchangeEE` is instantiated with the given YAML file, where
 the user needs to specify how the replicas should be set up or interact with each 

ensemble_md/cli/run_REXEE.py

@@ -44,6 +44,12 @@ def initialize(args):
                         help='The file path of the NPY file containing the time series of the whole-range\
                             alchemical weights. This file is a necessary input if one wants to update the \
                             file when extending a weight-updating simulation. (Default: g_vecs.npy)')
+    parser.add_argument('-e',
+                        '--equil',
+                        type=str,
+                        default='equil.npy',
+                        help='The file path of the NPY file containing the equilibration times for all simulations \
+                            when completing a variable weight REXEE simulation. (Default: equil.npy)')
     parser.add_argument('-o',
                         '--output',
                         type=str,
@@ -124,11 +130,15 @@ def main():
                         shutil.rmtree(f'{REXEE.working_dir}/sim_{i}/iteration_{j}')
 
             # Read g_vecs.npy and rep_trajs.npy so that new data can be appended, if any.
+            # Read equil.npy if running variable weight REXEE simulations
             # Note that these two arrays are created in rank 0 and should always be operated in rank 0,
             # or broadcasting is required.
             REXEE.rep_trajs = [list(i) for i in ckpt_data]
             if os.path.isfile(args.g_vecs) is True:
                 REXEE.g_vecs = [list(i) for i in np.load(args.g_vecs)]
+            if REXEE.fixed_weights is not True and os.path.isfile(args.equil) is True:
+                REXEE.equil = np.load(args.equil)
+            print(REXEE.equil)
         else:
             start_idx = None
 
@@ -322,16 +332,20 @@ def main():
             if (i + 1) % REXEE.n_ckpt == 0:
                 if len(REXEE.g_vecs) != 0:
                     # Save g_vec as a function of time if weight combination was used.
-                    np.save('g_vecs.npy', REXEE.g_vecs)
+                    np.save(args.g_vecs, REXEE.g_vecs)
 
                 print('\n----- Saving .npy files to checkpoint the simulation ---')
-                np.save('rep_trajs.npy', REXEE.rep_trajs)
+                np.save(args.ckpt, REXEE.rep_trajs)
+                if REXEE.fixed_weights is not True:
+                    np.save(args.equil, REXEE.equil)
 
     # Save the npy files at the end of the simulation anyway.
     if rank == 0:
         if len(REXEE.g_vecs) != 0:  # The length will be 0 only if there is no weight combination.
-            np.save('g_vecs.npy', REXEE.g_vecs)
-        np.save('rep_trajs.npy', REXEE.rep_trajs)
+            np.save(args.g_vecs, REXEE.g_vecs)
+        np.save(args.ckpt, REXEE.rep_trajs)
+        if REXEE.fixed_weights is not True:
+            np.save(args.equil, REXEE.equil)
 
     # Step 5: Write a summary for the simulation ensemble
     if rank == 0:

ensemble_md/replica_exchange_EE.py

@@ -1340,7 +1340,16 @@ def combine_weights(self, weights, weights_err=None, print_values=True):
                 dg_vec.append(utils.weighted_mean(dg_list, dg_err_list)[0])
 
         dg_vec.insert(0, 0)
-        g_vec = np.array([sum(dg_vec[:(i + 1)]) for i in range(len(dg_vec))])
+        nan_loc = [i for i, x in enumerate(dg_vec) if np.isnan(x)]
+        if len(nan_loc) != 0:
+            g_vec = np.zeros(len(dg_vec))
+            for i in range(1, len(dg_vec)):
+                if i in nan_loc:
+                    continue
+                else:
+                    g_vec[i] = g_vec[i-1] + dg_vec[i]
+        else:
+            g_vec = np.array([sum(dg_vec[:(i + 1)]) for i in range(len(dg_vec))])
 
         # (3) Determine the vector of alchemical weights for each replica
         weights_modified = np.zeros_like(weights)

ensemble_md/tests/test_replica_exchange_EE.py

@@ -870,6 +870,20 @@ def test_combine_weights(self, params_dict):
             [0, -0.40723412, 0.95296164, 1.95296164]])
         assert np.allclose(list(g_vec_2), [0, 2.1, 3.861407249466951, 3.4541731330165306, 4.814368891580968, 5.814368891580968])  # noqa: E501
 
+        # Test 3: MT-REXEE
+        REXEE.n_tot = 27
+        REXEE.n_sub = 9
+        REXEE.s = 9
+        REXEE.n_sim = 3
+        REXEE.state_ranges = [[0, 1, 2, 3, 4, 5, 6, 7, 8],
+                              [9, 10, 11, 12, 13, 14, 15, 16, 17],
+                              [18, 19, 20, 21, 22, 23, 24, 25, 26]]
+        weights = [[0.0, 0.03813, 0.08744, 0.58124, 1.42376, 1.86745, 3.24031, 3.09609, 3.5702],
+                   [0.0, 0.26761, 0.12656, 1.28994, 2.58161, 3.40522, 5.14597, 5.1271, 4.71232],
+                   [0.0, -0.24036, -0.21415, 0.90212, 1.88597, 3.5445, 4.62079, 4.48149, 4.84671]]
+        w_3, g_vec_3 = REXEE.combine_weights(weights)
+        assert np.allclose(list(g_vec_3), [0.0, 0.03813, 0.08744, 0.58124, 1.42376, 1.86745, 3.24031, 3.09609, 3.5702, 0.0, 0.26761, 0.12656, 1.28994, 2.58161, 3.40522, 5.14597, 5.1271, 4.71232, 0.0, -0.24036, -0.21415, 0.90212, 1.88597, 3.5445, 4.62079, 4.48149, 4.84671])  # noqa: E501
+
     def test_histogram_correction(self, params_dict):
         REXEE = get_REXEE_instance(params_dict)
         REXEE.n_tot = 6