Merge pull request #2779 from pybamm-team/electrode-soh-solve-output

make ElectrodeSOH.solve output {str: float} dict instead of Solution}

Author: valentinsulzer

CHANGELOG.md

@@ -18,6 +18,7 @@
 
 ## Breaking changes
 
+- `ElectrodeSOH.solve` now returns a `{str: float}` dict instead of a `pybamm.Solution` object (to avoid having to do `.data[0]` every time). In any code that uses `sol = ElectrodeSOH.solve()`, `sol[key].data[0]` should be replaced with `sol[key]`. ([#2779](https://github.com/pybamm-team/PyBaMM/pull/2779))
 - Removed "... cation signed stoichiometry" and "... electrons in reaction" parameters, they are now hardcoded. ([#2778](https://github.com/pybamm-team/PyBaMM/pull/2778))
 - When using `solver.step()`, the first time point in the step is shifted by `pybamm.settings.step_start_offset` (default 1 ns) to avoid having duplicate times in the solution steps from the end of one step and the start of the next. ([#2773](https://github.com/pybamm-team/PyBaMM/pull/2773))
 - Renamed "Measured open circuit voltage [V]" to "Surface open-circuit voltage [V]". This variable was calculated from surface particle concentrations, and hence "hid" the overpotential from particle gradients. The new variable "Open-circuit voltage [V]" is calculated from bulk particle concentrations instead. ([#2740](https://github.com/pybamm-team/PyBaMM/pull/2740))

examples/notebooks/models/electrode-state-of-health.ipynb

@@ -255,7 +255,7 @@
                 "esoh_sol = esoh_solver.solve(inputs)\n",
                 "\n",
                 "for var in [\"x_100\", \"y_100\", \"Q\", \"x_0\", \"y_0\"]:\n",
-                "    print(var, \":\", esoh_sol[var].data[0])"
+                "    print(var, \":\", esoh_sol[var])"
             ]
         },
         {
@@ -373,7 +373,7 @@
                 "        try:\n",
                 "            sol = esoh_solver.solve(inputs)\n",
                 "            for var in variables:\n",
-                "                sweep[var].append(sol[var].data[0])\n",
+                "                sweep[var].append(sol[var])\n",
                 "        except (ValueError, pybamm.SolverError):\n",
                 "            pass\n",
                 "\n",
@@ -417,13 +417,13 @@
                 "            else:\n",
                 "                label1 = label2 = label3 = None\n",
                 "            ax.plot(sweep[\"Q_Li\"], sweep[k],\"b-\", label=label1)\n",
-                "            ax.axhline(sol_init_QLi[k].data[0],c=\"k\",linestyle=\"--\", label=label2)\n",
-                "            ax.axhline(sol_init_Q[k].data[0],c=\"r\",linestyle=\"--\", label=label3)\n",
+                "            ax.axhline(sol_init_QLi[k],c=\"k\",linestyle=\"--\", label=label2)\n",
+                "            ax.axhline(sol_init_Q[k],c=\"r\",linestyle=\"--\", label=label3)\n",
                 "        ax.set_xlabel(\"Cyclable lithium [A.h]\")\n",
                 "        ax.set_ylabel(ks[0][0])\n",
                 "        ax.set_xlim([np.min(sweep[\"Q_Li\"]),np.max(sweep[\"Q_Li\"])])\n",
-                "        ax.axvline(sol_init_QLi[\"Q_Li\"].data[0],c=\"k\",linestyle=\"--\")\n",
-                "        ax.axvline(sol_init_Q[\"Q_Li\"].data[0],c=\"r\",linestyle=\"--\")\n",
+                "        ax.axvline(sol_init_QLi[\"Q_Li\"],c=\"k\",linestyle=\"--\")\n",
+                "        ax.axvline(sol_init_Q[\"Q_Li\"],c=\"r\",linestyle=\"--\")\n",
                 "        # Plot capacities of electrodes\n",
                 "        # ax.axvline(Qn,c=\"b\",linestyle=\"--\")\n",
                 "        # ax.axvline(Qp,c=\"r\",linestyle=\"--\")\n",

pybamm/models/full_battery_models/lithium_ion/electrode_soh.py

@@ -243,7 +243,8 @@ def solve(self, inputs):
                 # if that didn't raise an error, raise the original error instead
                 raise split_error
 
-        return sol
+        sol_dict = {key: sol[key].data[0] for key in sol.all_models[0].variables.keys()}
+        return sol_dict
 
     def _set_up_solve(self, inputs):
         # Try with full sim
@@ -501,7 +502,7 @@ def get_min_max_stoichiometries(self):
             inputs = {"Q_n": Q_n, "Q_p": Q_p, "Q": Q}
         # Solve the model and check outputs
         sol = self.solve(inputs)
-        return [sol[var].data[0] for var in ["x_0", "x_100", "y_100", "y_0"]]
+        return [sol["x_0"], sol["x_100"], sol["y_100"], sol["y_0"]]
 
 
 def get_initial_stoichiometries(

pybamm/solvers/solution.py

@@ -877,7 +877,6 @@ def _get_cycle_summary_variables(cycle_solution, esoh_solver):
                 "`sim.solve(calc_esoh=False)` to skip this step"
             )
 
-        for var in esoh_sol.all_models[0].variables:
-            cycle_summary_variables[var] = esoh_sol[var].data[0]
+        cycle_summary_variables.update(esoh_sol)
 
     return cycle_summary_variables

tests/unit/test_models/test_full_battery_models/test_lithium_ion/test_electrode_soh.py

@@ -23,23 +23,23 @@ def test_known_solution(self):
         # Solve the model and check outputs
         sol = esoh_solver.solve(inputs)
 
-        self.assertAlmostEqual(sol["Up(y_100) - Un(x_100)"].data[0], Vmax, places=5)
-        self.assertAlmostEqual(sol["Up(y_0) - Un(x_0)"].data[0], Vmin, places=5)
-        self.assertAlmostEqual(sol["Q_Li"].data[0], Q_Li, places=5)
+        self.assertAlmostEqual(sol["Up(y_100) - Un(x_100)"], Vmax, places=5)
+        self.assertAlmostEqual(sol["Up(y_0) - Un(x_0)"], Vmin, places=5)
+        self.assertAlmostEqual(sol["Q_Li"], Q_Li, places=5)
 
         # Solve with split esoh and check outputs
         ics = esoh_solver._set_up_solve(inputs)
         sol_split = esoh_solver._solve_split(inputs, ics)
-        for key in sol.all_models[0].variables:
-            self.assertAlmostEqual(sol[key].data[0], sol_split[key].data[0], places=5)
+        for key in sol:
+            self.assertAlmostEqual(sol[key], sol_split[key].data[0], places=5)
 
         # should still work with old inputs
         n_Li = parameter_values.evaluate(param.n_Li_particles_init)
         inputs = {"V_min": 3, "V_max": 4.2, "n_Li": n_Li, "C_n": Q_n, "C_p": Q_p}
 
         # Solve the model and check outputs
         sol = esoh_solver.solve(inputs)
-        self.assertAlmostEqual(sol["Q_Li"].data[0], Q_Li, places=5)
+        self.assertAlmostEqual(sol["Q_Li"], Q_Li, places=5)
 
     def test_known_solution_cell_capacity(self):
         param = pybamm.LithiumIonParameters()
@@ -60,9 +60,9 @@ def test_known_solution_cell_capacity(self):
         # Solve the model and check outputs
         sol = esoh_solver.solve(inputs)
 
-        self.assertAlmostEqual(sol["Up(y_100) - Un(x_100)"].data[0], Vmax, places=5)
-        self.assertAlmostEqual(sol["Up(y_0) - Un(x_0)"].data[0], Vmin, places=5)
-        self.assertAlmostEqual(sol["Q"].data[0], Q, places=5)
+        self.assertAlmostEqual(sol["Up(y_100) - Un(x_100)"], Vmax, places=5)
+        self.assertAlmostEqual(sol["Up(y_0) - Un(x_0)"], Vmin, places=5)
+        self.assertAlmostEqual(sol["Q"], Q, places=5)
 
     def test_error(self):
         param = pybamm.LithiumIonParameters()