[ModelicaSystem] split simulate() into two methods

[syntron]

[ModelicaSystem] split simulate() into two methods

(1) create ModelicasystemCmd instance - simulate_cmd()
(2) run it - simulate()

reason:

• use the instances of ModelicaSystemCmd to run the executeable with different settings as often as needed

[adeas31]

I didn't understand what this change is doing. Maybe you can add a simple usage as test.

[syntron]

@adeas31 splitting simulate into two parts allows to define the command to run the executable without running it. Thus, several runs can be defined and later be executed using the same executable. See PR #312; it also contains an example as unittest where this is used.

The example runs a DoE including structural and non-structural parameters. While any combination of non-structural parameters can be run using the same executable, any change of a structural parameter needs a rebuild of the executable. The new class - ModelicaSystemDoE - prepares all runs of the DoE (builing the model executable if needed) and then executes them in parallel.

This also relates to issue #230

[adeas31]

Still confused. I see that simulate sets _result_file which will not be set if I just use simulate_cmd. For example,

mod = OMPython.ModelicaSystem(....)
mod_sim_cmd = mod.simulate_cmd(....)
mod_sim_cmd.run()
mod_sim_cmd.args_set(.....)
mod_sim_cmd.run()

The above pseudo code will not set _result_file of ModelicaSystem class, right? Am I missing something?

[syntron]

@adeas31 your analyses is completly correct!

simulate_cmd() is within this PR only the preparation; the functionality of simulate() is splitted into two parts:

(1) prepare all such that a simulation can be run => simulate_cmd() which gets the result file as argument (required!)
(2) run the simulation within ModelicaSystem => simulate() using simulate_cmd()

In the current state, nothing changes; however, if you would like to run a bigger DoE, this allows to define one model within ModelicaSystem (define & build the executable) and then use simulate_cmd() to create serveral instances (containers) which allow to run a simulation using the executable with different settings (changing non-structural parameters).

The result file is not fixed within simulate_cmd() but provided as parameters such that it is possible to define a bunch of simulations in a first step and then run these in a loop / in several threads. This is shown by ModelicaSystemDoE (see PR #312 and especially the defined test). Here, the filenames of the results are also tracked such that all result data can later be read using getSolution() as it allows to provide a result filename.

Additional to the result file, it must also be ensured that the csv file used as input for the executable does not use the same filename. This is done by PR #313 - here, the csv filename can also be provided. Within ModelicaSystemDoE, it is defined based on the used name for the result file.

Regarding the pyseudo code, you have to define the result file to use:

mod = OMPython.ModelicaSystem(....)

# run 1
mod_sim_cmd = mod.simulate_cmd(result_file=result_file1, ....)
mod_sim_cmd.args_set(.....)
mod_sim_cmd.run()

# run 2
mod_sim_cmd = mod.simulate_cmd(result_file=result_file2, ....)
mod_sim_cmd.args_set(.....)
mod_sim_cmd.run()