Spaces:
Running
Running
File size: 9,827 Bytes
07f408f |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 |
import math
import torch
from torch.optim.optimizer import Optimizer
class AdaBelief(Optimizer):
r"""Implements AdaBelief algorithm. Modified from Adam in PyTorch
Arguments:
params (iterable): iterable of parameters to optimize or dicts defining
parameter groups
lr (float, optional): learning rate (default: 1e-3)
betas (Tuple[float, float], optional): coefficients used for computing
running averages of gradient and its square (default: (0.9, 0.999))
eps (float, optional): term added to the denominator to improve
numerical stability (default: 1e-16)
weight_decay (float, optional): weight decay (L2 penalty) (default: 0)
amsgrad (boolean, optional): whether to use the AMSGrad variant of this
algorithm from the paper `On the Convergence of Adam and Beyond`_
(default: False)
decoupled_decay (boolean, optional): (default: True) If set as True, then
the optimizer uses decoupled weight decay as in AdamW
fixed_decay (boolean, optional): (default: False) This is used when weight_decouple
is set as True.
When fixed_decay == True, the weight decay is performed as
$W_{new} = W_{old} - W_{old} \times decay$.
When fixed_decay == False, the weight decay is performed as
$W_{new} = W_{old} - W_{old} \times decay \times lr$. Note that in this case, the
weight decay ratio decreases with learning rate (lr).
rectify (boolean, optional): (default: True) If set as True, then perform the rectified
update similar to RAdam
degenerated_to_sgd (boolean, optional) (default:True) If set as True, then perform SGD update
when variance of gradient is high
reference: AdaBelief Optimizer, adapting stepsizes by the belief in observed gradients, NeurIPS 2020
For a complete table of recommended hyperparameters, see https://github.com/juntang-zhuang/Adabelief-Optimizer'
For example train/args for EfficientNet see these gists
- link to train_scipt: https://gist.github.com/juntang-zhuang/0a501dd51c02278d952cf159bc233037
- link to args.yaml: https://gist.github.com/juntang-zhuang/517ce3c27022b908bb93f78e4f786dc3
"""
def __init__(
self, params, lr=1e-3, betas=(0.9, 0.999), eps=1e-16, weight_decay=0, amsgrad=False,
decoupled_decay=True, fixed_decay=False, rectify=True, degenerated_to_sgd=True):
if not 0.0 <= lr:
raise ValueError("Invalid learning rate: {}".format(lr))
if not 0.0 <= eps:
raise ValueError("Invalid epsilon value: {}".format(eps))
if not 0.0 <= betas[0] < 1.0:
raise ValueError("Invalid beta parameter at index 0: {}".format(betas[0]))
if not 0.0 <= betas[1] < 1.0:
raise ValueError("Invalid beta parameter at index 1: {}".format(betas[1]))
if isinstance(params, (list, tuple)) and len(params) > 0 and isinstance(params[0], dict):
for param in params:
if 'betas' in param and (param['betas'][0] != betas[0] or param['betas'][1] != betas[1]):
param['buffer'] = [[None, None, None] for _ in range(10)]
defaults = dict(
lr=lr, betas=betas, eps=eps, weight_decay=weight_decay, amsgrad=amsgrad,
degenerated_to_sgd=degenerated_to_sgd, decoupled_decay=decoupled_decay, rectify=rectify,
fixed_decay=fixed_decay, buffer=[[None, None, None] for _ in range(10)])
super(AdaBelief, self).__init__(params, defaults)
def __setstate__(self, state):
super(AdaBelief, self).__setstate__(state)
for group in self.param_groups:
group.setdefault('amsgrad', False)
@torch.no_grad()
def reset(self):
for group in self.param_groups:
for p in group['params']:
state = self.state[p]
amsgrad = group['amsgrad']
# State initialization
state['step'] = 0
# Exponential moving average of gradient values
state['exp_avg'] = torch.zeros_like(p)
# Exponential moving average of squared gradient values
state['exp_avg_var'] = torch.zeros_like(p)
if amsgrad:
# Maintains max of all exp. moving avg. of sq. grad. values
state['max_exp_avg_var'] = torch.zeros_like(p)
@torch.no_grad()
def step(self, closure=None):
"""Performs a single optimization step.
Arguments:
closure (callable, optional): A closure that reevaluates the model
and returns the loss.
"""
loss = None
if closure is not None:
with torch.enable_grad():
loss = closure()
for group in self.param_groups:
for p in group['params']:
if p.grad is None:
continue
grad = p.grad
if grad.dtype in {torch.float16, torch.bfloat16}:
grad = grad.float()
if grad.is_sparse:
raise RuntimeError(
'AdaBelief does not support sparse gradients, please consider SparseAdam instead')
p_fp32 = p
if p.dtype in {torch.float16, torch.bfloat16}:
p_fp32 = p_fp32.float()
amsgrad = group['amsgrad']
beta1, beta2 = group['betas']
state = self.state[p]
# State initialization
if len(state) == 0:
state['step'] = 0
# Exponential moving average of gradient values
state['exp_avg'] = torch.zeros_like(p_fp32)
# Exponential moving average of squared gradient values
state['exp_avg_var'] = torch.zeros_like(p_fp32)
if amsgrad:
# Maintains max of all exp. moving avg. of sq. grad. values
state['max_exp_avg_var'] = torch.zeros_like(p_fp32)
# perform weight decay, check if decoupled weight decay
if group['decoupled_decay']:
if not group['fixed_decay']:
p_fp32.mul_(1.0 - group['lr'] * group['weight_decay'])
else:
p_fp32.mul_(1.0 - group['weight_decay'])
else:
if group['weight_decay'] != 0:
grad.add_(p_fp32, alpha=group['weight_decay'])
# get current state variable
exp_avg, exp_avg_var = state['exp_avg'], state['exp_avg_var']
state['step'] += 1
bias_correction1 = 1 - beta1 ** state['step']
bias_correction2 = 1 - beta2 ** state['step']
# Update first and second moment running average
exp_avg.mul_(beta1).add_(grad, alpha=1 - beta1)
grad_residual = grad - exp_avg
exp_avg_var.mul_(beta2).addcmul_(grad_residual, grad_residual, value=1 - beta2)
if amsgrad:
max_exp_avg_var = state['max_exp_avg_var']
# Maintains the maximum of all 2nd moment running avg. till now
torch.max(max_exp_avg_var, exp_avg_var.add_(group['eps']), out=max_exp_avg_var)
# Use the max. for normalizing running avg. of gradient
denom = (max_exp_avg_var.sqrt() / math.sqrt(bias_correction2)).add_(group['eps'])
else:
denom = (exp_avg_var.add_(group['eps']).sqrt() / math.sqrt(bias_correction2)).add_(group['eps'])
# update
if not group['rectify']:
# Default update
step_size = group['lr'] / bias_correction1
p_fp32.addcdiv_(exp_avg, denom, value=-step_size)
else:
# Rectified update, forked from RAdam
buffered = group['buffer'][int(state['step'] % 10)]
if state['step'] == buffered[0]:
num_sma, step_size = buffered[1], buffered[2]
else:
buffered[0] = state['step']
beta2_t = beta2 ** state['step']
num_sma_max = 2 / (1 - beta2) - 1
num_sma = num_sma_max - 2 * state['step'] * beta2_t / (1 - beta2_t)
buffered[1] = num_sma
# more conservative since it's an approximated value
if num_sma >= 5:
step_size = math.sqrt(
(1 - beta2_t) *
(num_sma - 4) / (num_sma_max - 4) *
(num_sma - 2) / num_sma *
num_sma_max / (num_sma_max - 2)) / (1 - beta1 ** state['step'])
elif group['degenerated_to_sgd']:
step_size = 1.0 / (1 - beta1 ** state['step'])
else:
step_size = -1
buffered[2] = step_size
if num_sma >= 5:
denom = exp_avg_var.sqrt().add_(group['eps'])
p_fp32.addcdiv_(exp_avg, denom, value=-step_size * group['lr'])
elif step_size > 0:
p_fp32.add_(exp_avg, alpha=-step_size * group['lr'])
if p.dtype in {torch.float16, torch.bfloat16}:
p.copy_(p_fp32)
return loss
|