What is the possible "reference" of get_standardized_data

[beckhamwjc]

Steps to reproduce

import nevergrad as ng

param = ng.p.Array(shape=(1, 10)).set_bounds(-2, 2)
optim = ng.optimzers.registry['PSO'](parametrization=param, budget=100)
x1 = optim.ask()

x1.get_standardized_data(0)
x1.get_standardized_data(1)

Observed Results

TypeError: get_standardized_data( ) takes 1 positional argument but 2 were given

Expected Results

I want to get normal output but I kept getting errors.

I've read the docs and the codes carefully but I still don't know what the "reference" is for get_standardized_data( ). What exactly am I supposed to provide get_standardized_data( ) besides "self"?

Thanks.

[StanczakDominik]

Well, according to the docstring of get_standardized_data:

Parameters
----------
reference: Parameter
    the reference instance for representation in the standardized data space. This keyword parameter is
    mandatory to make the code clearer.
    If you use "self", this method will always return a zero vector.

So, with your example,

>>> x1.get_standardized_data(reference=param)
array([-1.40424398,  1.32470753, -0.73157793, -0.22966067, -1.39042444,
        1.68136875,  1.40945075, -0.78553276,  1.75506259, -1.94768554])

Hope that helps!

[jrapin]

Exactly ;)
The reference is basically the origin of the space (param.get_standardized_data(reference=param) returns a null vector). You can use the origin that you want depending on your needs, but usually using the initial param is the simpler.