from pprint import pformat as pf
from sconce.schedules.base import Schedule
import math
import numpy as np
[docs]class Cosine(Schedule):
"""
A Schedule where the hyperparameter follows a scaled and shifted cosine function
from [0, pi]. It will begin at <initial_value> and end at <final_value>, after <num_steps>.
Arguments:
initial_value (float): the initial value of the hyperparameter.
final_value (float): the final value of the hyperparameter.
"""
def __init__(self, initial_value, final_value):
self.initial_value = initial_value
self.final_value = final_value
def __repr__(self):
return f'{self.__class__.__name__}(initial_value={pf(self.initial_value)}, final_value={pf(self.final_value)})'
[docs] def set_num_steps(self, num_steps):
self.num_steps = num_steps
self.progressions = np.linspace(0, 1, num_steps)
def _get_value(self, step, current_state):
progression = self.progressions[step - 1]
new_value = (self.initial_value +
(self.final_value - self.initial_value) *
(1 + math.cos(math.pi * progression)) / 2)
return new_value