syne_tune.optimizer.schedulers.synchronous.hyperband_bracket module

class syne_tune.optimizer.schedulers.synchronous.hyperband_bracket.SlotInRung(rung_index, level, slot_index, trial_id, metric_val)[source]

Bases: object

Used to communicate slot positions and content for them.

rung_index: int

level: int

slot_index: int

trial_id: Optional[int]

metric_val: Optional[float]

class syne_tune.optimizer.schedulers.synchronous.hyperband_bracket.SynchronousBracket(mode)[source]

Bases: object

Base class for a single bracket in synchronous Hyperband algorithms.

A bracket consists of a list of rungs. Each rung consists of a number of slots and a resource level (called rung level). The larger the rung level, the smaller the number of slots.

A slot is occupied (by a metric value), free, or pending. A pending slot has already been returned by next_free_slot(). Slots in the lowest rung (smallest rung level, largest size) are filled first. At any point in time, only slots in the lowest not fully occupied rung can be filled. If there are no free slots in the current rung, but there are pending ones, the bracket is blocked, and another bracket needs to be worked on.

static assert_check_rungs(rungs)[source]

property num_rungs: int

is_bracket_complete()[source]

Return type:: bool

num_pending_slots()[source]

Return type:: int
Returns:: Number of pending slots (have been returned by next_free_slot, but not yet occupied

next_free_slot()[source]

Return type:: Optional[SlotInRung]

on_result(result)[source]

Provides result for slot previously requested by next_free_slot. Here, result.metric is written to the slot in order to make it occupied. Also, result.trial_id is written there.

We normally return None. But if the result passed completes the current rung, this triggers the creation of a child run which consists of promoted trials from the current rung. In this case, we return the IDs of trials which have not been promoted. This is used in for early removal of checkpoints, see trials_checkpoints_can_be_removed().

Parameters:: result (SlotInRung) – See above
Return type:: Optional[List[int]]
Returns:: See above

class syne_tune.optimizer.schedulers.synchronous.hyperband_bracket.SynchronousHyperbandBracket(rungs, mode)[source]

Bases: SynchronousBracket

Represents a bracket in standard synchronous Hyperband.

When a rung is fully occupied, slots for the next rung are assigned with the trial_id’s having the best metric values. At any point in time, only slots in the lowest not fully occupied rung can be filled.

property num_rungs: int

syne_tune.optimizer.schedulers.synchronous.hyperband_bracket.get_top_list(rung, new_len, mode)[source]

Returns list of IDs of trials of len new_len which should be promoted, because they performed best. We also return the list of IDs of the remaining trials, which are not to be promoted.

Parameters:

rung (List[Tuple[int, float]]) – Current rung which has just been completed
new_len (int) – Size of new rung
mode (str) – “min” or “max”

Return type:

(List[int], List[int])

Returns:

(top_list, remaining_list)