[Question/Issue] Choice parameters don't work with string values

[Irynei]

I was trying to do optimization using choice parameters. Here is a simple example:

best_parameters, values, experiment, model = optimize(
    parameters=[
        {'name': 'categorical', 'type': 'choice', 'values': ['foo', 'bar']}
    ],
    evaluation_function=objective,
    minimize=True,
)

And I got the following error:

Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/service/managed_loop.py", line 206, in optimize
loop.full_run()
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/service/managed_loop.py", line 150, in full_run
self.run_trial()
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/service/managed_loop.py", line 130, in run_trial
experiment=self.experiment, new_data=dat
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/core/experiment.py", line 446, in new_trial
experiment=self, trial_type=trial_type, generator_run=generator_run
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/core/trial.py", line 38, in init
self.add_generator_run(generator_run=generator_run)
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/core/base_trial.py", line 85, in _immutable_once_run
return func(self, *args, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/core/trial.py", line 87, in add_generator_run
generator_run.arms[0].parameters, raise_error=True
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/ax/core/search_space.py", line 192, in check_types
f"{value} is not a valid value for "
ValueError: bar is not a valid value for parameter ChoiceParameter(name='categorical', parameter_type=STRING, values=['foo', 'bar'])

Digging into that, I found that the problem was with the one_hot transformer, it changed the type of string values to numpy.str_ and hence, the ValueError was raised.

I see that this is already fixed in this commit, but it's not available in the currently latest 0.1.1 tag.

Could you please provide information when the new release is going to be?
Thank you!

[ldworkin]

Hi @Irynei! I think we're planning to do a new release tomorrow :) In the meantime (or in the future) you can try pulling from master and then doing pip install -e ..

[Irynei]

Cool, thanks.

[ldworkin]

Closing, since this should be in our current release (0.1.2)