Getting notified when algorithm is terminated

[ThomasEwaldETH]

Hello everyone!
First, thanks for maintaining this great package! It is very convenient and helpful for me!

To my optimization problem:
During my optimization, I use the Callback class to get notified every time a generation is evaluated. I then take these results and put them into a plot, so that my algorithm does some sort of 'runtime plotting' of the status of the optimization, and I can see how the Pareto front forms. This works very smoothly and is exactly what I need. In addition, I show the current iteration number as the plot title. Here is an example:

classPlotStandalone(Callback):
    def __init__(self) -> None:
        super().__init__()
        self.fig = plt.figure(1)
        self.axes = self.fig.add_subplot()

    def notify(self, algorithm: NSGA2) -> None:
        population = algorithm.pop
        iteration = algorithm.n_iter
        values = population.get("F")
        x = values[:, 0]
        y = values[:, 1]
        self.plot(x, y, iteration)

    def plot(self, x: "npt.NDArray", y: "npt.NDArray", it: int) -> None:
        ... # plots in self.axes

To my question:
I was wondering whether I can check if the algorithm has terminated? After finishing, I want to plot some additional information. My actual code runs the optimization with the minimize() method. When finished, I access the results object and do this “manually”. However, I would prefer a solution where my notify method realizes the termination and can call another function, that does the post-processing. The reason is, that the post-processing is again changing stuff in the plot (plotting my favorite solution) and I want to have that inside the Callback class, like this:

classPlotStandalone(Callback):
    def __init__(self) -> None:
        ...

    def notify(self, algorithm: NSGA2) -> None:
        if terminated:
            ...
            self.has_terminated(...)
        else:
            ...
            self.plot(x, y, iteration)

    def plot(self, ...) -> None:
        ...

    def has_terminated(self, ...) -> None:
        ...

So, is that possible? Is there something like a flag in the Termination object, that indicates "final generation reached" or something?

Best regards and have a nice day,
Thomas

[cyrilpic]

The callback is called after the termination object has been updated. So, in your notify method, you can check if algorithm.termination.has_terminated() is True.

[ThomasEwaldETH]

That's great, thanks a lot (tested it in my code, and it works exactly like I had it in mind)!
Best regards,
Thomas

[blankjul]

I have nothing to add. I would have suggested exactly the same.

@cyrilpic Thank you very much for helping out here :)