Issue with empty u_new leading to IndexError in ESSearch

[toniramo]

Hi,

In PyBADS version 1.0.5, I’m occasionally encountering an issue where, in ESSearch, if u_new is empty after the constraint check (starting from line 142), an IndexError occurs:

File "c:\Hyapp\Anaconda3-2023.07-2\Lib\site-packages\pybads\search\es_search.py", line 210, in ESSearch.__call__
    return us[0], z[0]
IndexError: index 0 is out of bounds for axis 0 with size 0

It appears there’s an intended fallback mechanism for random search if the acquisition function fails (lines 164–169), but this doesn’t work if u_new is empty, as z_candidates will also be empty:

# Fallback random search if acquisition fails
if z_new is None or z_new.size == 0:
    z_candidates = np.random.rand(u_new.shape[0])
    self.logger.warn("bads:es_search: Something went wrong with the acquisition function, random search is performed")

Would you be able to clarify if a fallback mechanism is intended in this situation, or if there might be an alternative approach to avoid this IndexError?

Thank you.

[lacerbi]

Thanks for your report, we'll investigate and get back to you.