Allow easily loading individual models (#476)

* Allow easily loading individual models

* Hopefully make the tests a tiny bit faster by not loading the whole network each time

tests/test_ase.py

@@ -25,7 +25,7 @@ def get_numeric_force(atoms, eps):
 class TestASE(unittest.TestCase):
 
     def setUp(self):
-        self.model = torchani.models.ANI1x().double()[0]
+        self.model = torchani.models.ANI1x(model_index=0).double()
 
     def testWithNumericalForceWithPBCEnabled(self):
         atoms = Diamond(symbol="C", pbc=True)

tests/test_energies.py

@@ -13,10 +13,10 @@ class TestEnergies(unittest.TestCase):
 
     def setUp(self):
         self.tolerance = 5e-5
-        ani1x = torchani.models.ANI1x()
-        self.aev_computer = ani1x.aev_computer
-        self.nnp = ani1x.neural_networks[0]
-        self.energy_shifter = ani1x.energy_shifter
+        model = torchani.models.ANI1x(model_index=0)
+        self.aev_computer = model.aev_computer
+        self.nnp = model.neural_networks
+        self.energy_shifter = model.energy_shifter
         self.nn = torchani.nn.Sequential(self.nnp, self.energy_shifter)
         self.model = torchani.nn.Sequential(self.aev_computer, self.nnp, self.energy_shifter)
 

tests/test_forces.py

@@ -12,9 +12,9 @@ class TestForce(unittest.TestCase):
 
     def setUp(self):
         self.tolerance = 1e-5
-        ani1x = torchani.models.ANI1x()
-        self.aev_computer = ani1x.aev_computer
-        self.nnp = ani1x.neural_networks[0]
+        model = torchani.models.ANI1x(model_index=0)
+        self.aev_computer = model.aev_computer
+        self.nnp = model.neural_networks
         self.model = torchani.nn.Sequential(self.aev_computer, self.nnp)
 
     def random_skip(self):

tests/test_structure_optim.py

@@ -15,8 +15,7 @@ class TestStructureOptimization(unittest.TestCase):
 
     def setUp(self):
         self.tolerance = 1e-6
-        self.ani1x = torchani.models.ANI1x()
-        self.calculator = self.ani1x[0].ase()
+        self.calculator = torchani.models.ANI1x(model_index=0).ase()
 
     def testRMSE(self):
         datafile = os.path.join(path, 'test_data/NeuroChemOptimized/all')

torchani/models.py

@@ -26,7 +26,7 @@
 Note that the class BuiltinModels can be accessed but it is deprecated and
 shouldn't be used anymore.
 """
-
+import os
 import torch
 from torch import Tensor
 from typing import Tuple, Optional
@@ -53,6 +53,45 @@ def __init__(self, species_converter, aev_computer, neural_networks, energy_shif
         self.consts = consts
         self.sae_dict = sae_dict
 
+    @classmethod
+    def _from_neurochem_resources(cls, info_file_path, periodic_table_index=False, model_index=0):
+        # this is used to load only 1 model (by default model 0)
+        consts, sae_file, ensemble_prefix, ensemble_size = cls._parse_neurochem_resources(info_file_path)
+        if (model_index >= ensemble_size):
+            raise ValueError("The ensemble size is only {}, model {} can't be loaded".format(ensemble_size, model_index))
+
+        species_converter = SpeciesConverter(consts.species)
+        aev_computer = AEVComputer(**consts)
+        energy_shifter, sae_dict = neurochem.load_sae(sae_file, return_dict=True)
+        species_to_tensor = consts.species_to_tensor
+
+        network_dir = os.path.join('{}{}'.format(ensemble_prefix, model_index), 'networks')
+        neural_networks = neurochem.load_model(consts.species, network_dir)
+
+        return cls(species_converter, aev_computer, neural_networks,
+                   energy_shifter, species_to_tensor, consts, sae_dict, periodic_table_index)
+
+    @staticmethod
+    def _parse_neurochem_resources(info_file_path):
+        def get_resource(file_path):
+            package_name = '.'.join(__name__.split('.')[:-1])
+            return resource_filename(package_name, 'resources/' + file_path)
+
+        info_file = get_resource(info_file_path)
+
+        with open(info_file) as f:
+            # const_file: Path to the file with the builtin constants.
+            # sae_file: Path to the file with the Self Atomic Energies.
+            # ensemble_prefix: Prefix of the neurochem resource directories.
+            lines = [x.strip() for x in f.readlines()][:4]
+            const_file_path, sae_file_path, ensemble_prefix_path, ensemble_size = lines
+            const_file = get_resource(const_file_path)
+            sae_file = get_resource(sae_file_path)
+            ensemble_prefix = get_resource(ensemble_prefix_path)
+            ensemble_size = int(ensemble_size)
+            consts = neurochem.Constants(const_file)
+        return consts, sae_file, ensemble_prefix, ensemble_size
+
     def forward(self, species_coordinates: Tuple[Tensor, Tensor],
                 cell: Optional[Tensor] = None,
                 pbc: Optional[Tensor] = None) -> SpeciesEnergies:
@@ -159,31 +198,15 @@ def __init__(self, species_converter, aev_computer, neural_networks,
 
     @classmethod
     def _from_neurochem_resources(cls, info_file_path, periodic_table_index=False):
-
-        def get_resource(file_path):
-            package_name = '.'.join(__name__.split('.')[:-1])
-            return resource_filename(package_name, 'resources/' + file_path)
-
-        info_file = get_resource(info_file_path)
-
-        with open(info_file) as f:
-            # const_file: Path to the file with the builtin constants.
-            # sae_file: Path to the file with the Self Atomic Energies.
-            # ensemble_prefix: Prefix of the neurochem resource directories.
-            lines = [x.strip() for x in f.readlines()][:4]
-            const_file_path, sae_file_path, ensemble_prefix_path, ensemble_size = lines
-            const_file = get_resource(const_file_path)
-            sae_file = get_resource(sae_file_path)
-            ensemble_prefix = get_resource(ensemble_prefix_path)
-            ensemble_size = int(ensemble_size)
-            consts = neurochem.Constants(const_file)
+        # this is used to load only 1 model (by default model 0)
+        consts, sae_file, ensemble_prefix, ensemble_size = cls._parse_neurochem_resources(info_file_path)
 
         species_converter = SpeciesConverter(consts.species)
         aev_computer = AEVComputer(**consts)
-        neural_networks = neurochem.load_model_ensemble(consts.species,
-                                                        ensemble_prefix, ensemble_size)
         energy_shifter, sae_dict = neurochem.load_sae(sae_file, return_dict=True)
         species_to_tensor = consts.species_to_tensor
+        neural_networks = neurochem.load_model_ensemble(consts.species,
+                                                        ensemble_prefix, ensemble_size)
 
         return cls(species_converter, aev_computer, neural_networks,
                    energy_shifter, species_to_tensor, consts, sae_dict, periodic_table_index)
@@ -220,7 +243,7 @@ def __len__(self):
         return len(self.neural_networks)
 
 
-def ANI1x(periodic_table_index=False):
+def ANI1x(periodic_table_index=False, model_index=None):
     """The ANI-1x model as in `ani-1x_8x on GitHub`_ and `Active Learning Paper`_.
 
     The ANI-1x model is an ensemble of 8 networks that was trained using
@@ -234,10 +257,13 @@ def ANI1x(periodic_table_index=False):
     .. _Active Learning Paper:
         https://aip.scitation.org/doi/abs/10.1063/1.5023802
     """
-    return BuiltinEnsemble._from_neurochem_resources('ani-1x_8x.info', periodic_table_index)
+    info_file = 'ani-1x_8x.info'
+    if model_index is None:
+        return BuiltinEnsemble._from_neurochem_resources(info_file, periodic_table_index)
+    return BuiltinModel._from_neurochem_resources(info_file, periodic_table_index, model_index)
 
 
-def ANI1ccx(periodic_table_index=False):
+def ANI1ccx(periodic_table_index=False, model_index=None):
     """The ANI-1ccx model as in `ani-1ccx_8x on GitHub`_ and `Transfer Learning Paper`_.
 
     The ANI-1ccx model is an ensemble of 8 networks that was trained
@@ -252,4 +278,7 @@ def ANI1ccx(periodic_table_index=False):
     .. _Transfer Learning Paper:
         https://doi.org/10.26434/chemrxiv.6744440.v1
     """
-    return BuiltinEnsemble._from_neurochem_resources('ani-1ccx_8x.info', periodic_table_index)
+    info_file = 'ani-1ccx_8x.info'
+    if model_index is None:
+        return BuiltinEnsemble._from_neurochem_resources(info_file, periodic_table_index)
+    return BuiltinModel._from_neurochem_resources(info_file, periodic_table_index, model_index)