Add keys to ParameterSet and update ECM OCV check (#388)

* Add keys to ParameterSet

* Remove pybamm import from exp_UKF

* Update CHANGELOG.md

* Update standalone model

CHANGELOG.md

@@ -25,6 +25,7 @@
 
 ## Bug Fixes
 
+- [#387](https://github.com/pybop-team/PyBOP/issues/387) - Adds keys to ParameterSet and updates ECM OCV check.
 - [#380](https://github.com/pybop-team/PyBOP/pull/380) - Restore self._boundaries construction for `pybop.PSO`
 - [#372](https://github.com/pybop-team/PyBOP/pull/372) - Converts `np.array` to `np.asarray` for Numpy v2.0 support.
 - [#165](https://github.com/pybop-team/PyBOP/issues/165) - Stores the attempted and best parameter values and the best cost for each iteration in the log attribute of the optimiser and updates the associated plots.

examples/scripts/exp_UKF.py

@@ -1,11 +1,10 @@
 import numpy as np
-import pybamm
 
 import pybop
 from examples.standalone.model import ExponentialDecay
 
 # Parameter set and model definition
-parameter_set = pybamm.ParameterValues({"k": "[input]", "y0": "[input]"})
+parameter_set = {"k": "[input]", "y0": "[input]"}
 model = ExponentialDecay(parameter_set=parameter_set, n_states=1)
 
 # Fitting parameters

examples/standalone/model.py

@@ -18,7 +18,8 @@ def __init__(
         parameter_set: pybamm.ParameterValues = None,
         n_states: int = 1,
     ):
-        super().__init__()
+        super().__init__(name=name, parameter_set=parameter_set)
+
         self.n_states = n_states
         if n_states < 1:
             raise ValueError("The number of states (n_states) must be greater than 0")
@@ -38,10 +39,11 @@ def __init__(
         )
 
         self._unprocessed_model = self.pybamm_model
-        self.name = name
 
         self.default_parameter_values = (
-            default_parameter_values if parameter_set is None else parameter_set
+            default_parameter_values
+            if self._parameter_set is None
+            else self._parameter_set
         )
         self._parameter_set = self.default_parameter_values
         self._unprocessed_parameter_set = self._parameter_set

pybop/models/empirical/base_ecm.py

@@ -52,14 +52,14 @@ def __init__(
         # Correct OCP if set to default
         if (
             parameter_set is not None
-            and "Open-circuit voltage [V]" in parameter_set.params
+            and "Open-circuit voltage [V]" in parameter_set.keys()
         ):
             default_ocp = self.pybamm_model.default_parameter_values[
                 "Open-circuit voltage [V]"
             ]
-            if parameter_set.params["Open-circuit voltage [V]"] == "default":
+            if parameter_set["Open-circuit voltage [V]"] == "default":
                 print("Setting open-circuit voltage to default function")
-                parameter_set.params["Open-circuit voltage [V]"] = default_ocp
+                parameter_set["Open-circuit voltage [V]"] = default_ocp
 
         super().__init__(name=name, parameter_set=parameter_set)
 

pybop/models/lithium_ion/base_echem.py

@@ -47,10 +47,7 @@ def __init__(
         solver=None,
         **model_kwargs,
     ):
-        super().__init__(
-            name=name,
-            parameter_set=parameter_set,
-        )
+        super().__init__(name=name, parameter_set=parameter_set)
 
         model_options = dict(build=False)
         for key, value in model_kwargs.items():

pybop/parameters/parameter_set.py

@@ -1,5 +1,6 @@
 import json
 import types
+from typing import List
 
 from pybamm import ParameterValues, parameter_sets
 
@@ -34,6 +35,12 @@ def __setitem__(self, key, value):
     def __getitem__(self, key):
         return self.params[key]
 
+    def keys(self) -> List:
+        """
+        A list of parameter names
+        """
+        return list(self.params.keys())
+
     def import_parameters(self, json_path=None):
         """
         Imports parameters from a JSON file specified by the `json_path` attribute.