from __future__ import annotations
from typing import Any
from smac.intensifier.successive_halving import SuccessiveHalving
[docs]class Hyperband(SuccessiveHalving):
"""See ``SuccessiveHalving`` for documentation."""
[docs] def reset(self) -> None:
"""Resets the internal variables of the intensifier, including the tracker and the next bracket."""
super().reset()
# Reset current bracket
self._next_bracket: int = 0
def __post_init__(self) -> None:
super().__post_init__()
min_budget = self._min_budget
max_budget = self._max_budget
assert min_budget is not None and max_budget is not None
eta = self._eta
# The only difference we have to do is change max_iterations, n_configs_in_stage, budgets_in_stage
self._s_max = self._get_max_iterations(eta, max_budget, min_budget) # type: ignore[operator]
self._max_iterations: dict[int, int] = {}
self._n_configs_in_stage: dict[int, list] = {}
self._budgets_in_stage: dict[int, list] = {}
for i in range(self._s_max + 1):
max_iter = self._s_max - i
self._budgets_in_stage[i], self._n_configs_in_stage[i] = self._compute_configs_and_budgets_for_stages(
eta, max_budget, max_iter, self._s_max
)
self._max_iterations[i] = max_iter + 1
[docs] def get_state(self) -> dict[str, Any]: # noqa: D102
state = super().get_state()
state["next_bracket"] = self._next_bracket
return state
[docs] def set_state(self, state: dict[str, Any]) -> None: # noqa: D102
super().set_state(state)
self._next_bracket = state["next_bracket"]
def _get_next_bracket(self) -> int:
"""In contrast to Successive Halving, Hyperband uses multiple brackets. Each time a new batch
is added to the tracker, the bracket is increased.
"""
current_bracket = self._next_bracket
next_bracket = current_bracket + 1
if next_bracket > self._s_max or next_bracket < 0:
next_bracket = 0
self._next_bracket = next_bracket
return current_bracket