#1329 Rob and Ferran comments

CHANGELOG.md

@@ -19,7 +19,8 @@
 
 ## Optimizations
 
--   If solver method `solve()` is passed a list of inputs as the `inputs` keyword argument, the resolution of the model for each input set is spread acrosss several Python processes, usually running in parallel on different processors. The default number of processes is the number of processors available. `solve()` takes a new keyword argument `nproc` which can be used to set this number a manually.
+-   The `Solution` class now only creates the concatenated `y` when the user asks for it. This is an optimization step as the concatenation can be slow, especially with larger experiments ([#1331](https://github.com/pybamm-team/PyBaMM/pull/1331))
+-   If solver method `solve()` is passed a list of inputs as the `inputs` keyword argument, the resolution of the model for each input set is spread across several Python processes, usually running in parallel on different processors. The default number of processes is the number of processors available. `solve()` takes a new keyword argument `nproc` which can be used to set this number a manually.
 -   Variables are now post-processed using CasADi ([#1316](https://github.com/pybamm-team/PyBaMM/pull/1316))
 -   Operations such as `1*x` and `0+x` now directly return `x` ([#1252](https://github.com/pybamm-team/PyBaMM/pull/1252))
 

pybamm/simulation.py

@@ -443,7 +443,7 @@ def solve(self, t_eval=None, solver=None, check_model=True, **kwargs):
             pybamm.logger.info("Start running experiment")
             timer = pybamm.Timer()
 
-            phases = []
+            steps = []
             for idx, (exp_inputs, dt) in enumerate(
                 zip(self._experiment_inputs, self._experiment_times)
             ):
@@ -454,13 +454,13 @@ def solve(self, t_eval=None, solver=None, check_model=True, **kwargs):
                 npts = max(int(round(dt / exp_inputs["period"])) + 1, 2)
                 self.step(dt, solver=solver, npts=npts, **kwargs)
 
-                # Extract the new parts of the solution to construct the entire "phase"
+                # Extract the new parts of the solution to construct the entire "step"
                 sol = self.solution
                 new_num_subsolutions = len(sol.sub_solutions)
                 diff_num_subsolutions = new_num_subsolutions - previous_num_subsolutions
                 previous_num_subsolutions = new_num_subsolutions
 
-                phase_solution = pybamm.Solution(
+                step_solution = pybamm.Solution(
                     sol.all_ts[-diff_num_subsolutions:],
                     sol.all_ys[-diff_num_subsolutions:],
                     sol.model,
@@ -469,9 +469,9 @@ def solve(self, t_eval=None, solver=None, check_model=True, **kwargs):
                     sol.y_event,
                     sol.termination,
                 )
-                phase_solution.solve_time = 0
-                phase_solution.integration_time = 0
-                phases.append(phase_solution)
+                step_solution.solve_time = 0
+                step_solution.integration_time = 0
+                steps.append(step_solution)
                 # Only allow events specified by experiment
                 if not (
                     self._solution.termination == "final time"
@@ -493,10 +493,10 @@ def solve(self, t_eval=None, solver=None, check_model=True, **kwargs):
             self.solution.cycles = []
             for cycle_num, cycle_length in enumerate(self.experiment.cycle_lengths):
                 cycle_start_idx = sum(self.experiment.cycle_lengths[0:cycle_num])
-                cycle_solution = phases[cycle_start_idx]
+                cycle_solution = steps[cycle_start_idx]
                 for idx in range(cycle_length - 1):
-                    cycle_solution = cycle_solution + phases[cycle_start_idx + idx + 1]
-                cycle_solution.phases = phases[
+                    cycle_solution = cycle_solution + steps[cycle_start_idx + idx + 1]
+                cycle_solution.steps = steps[
                     cycle_start_idx : cycle_start_idx + cycle_length
                 ]
                 self.solution.cycles.append(cycle_solution)

pybamm/solvers/solution.py

@@ -12,9 +12,8 @@
 
 class Solution(object):
     """
-    (Semi-private) class containing the solution of, and various attributes associated
-    with, a PyBaMM model. This class is automatically created by the `Solution` class,
-    and should never be called from outside the `Solution` class.
+    Class containing the solution of, and various attributes associated with, a PyBaMM
+    model.
 
     Parameters
     ----------