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PiecewiseLinear#

class ignite.handlers.param_scheduler.PiecewiseLinear(optimizer, param_name, milestones_values, save_history=False, param_group_index=None)[source]#

Piecewise linear parameter scheduler

Parameters
  • optimizer (Optimizer) – torch optimizer or any object with attribute param_groups as a sequence.

  • param_name (str) – name of optimizer’s parameter to update.

  • milestones_values (List[Tuple[int, float]]) – list of tuples (event index, parameter value) represents milestones and parameter. Milestones should be increasing integers.

  • save_history (bool) – whether to log the parameter values to engine.state.param_history, (default=False).

  • param_group_index (Optional[int]) – optimizer’s parameters group to use.

scheduler = PiecewiseLinear(optimizer, "lr",
                            milestones_values=[(10, 0.5), (20, 0.45), (21, 0.3), (30, 0.1), (40, 0.1)])
# Attach to the trainer
trainer.add_event_handler(Events.ITERATION_STARTED, scheduler)
#
# Sets the learning rate to 0.5 over the first 10 iterations, then decreases linearly from 0.5 to 0.45 between
# 10th and 20th iterations. Next there is a jump to 0.3 at the 21st iteration and LR decreases linearly
# from 0.3 to 0.1 between 21st and 30th iterations and remains 0.1 until the end of the iterations.
#

New in version 0.4.5.

Methods

get_param

Method to get current parameter values

get_param()[source]#

Method to get current parameter values

Returns

list of params, or scalar param

Return type

float