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3cd1076 | 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 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
import math
import torch
from torch.optim.optimizer import Optimizer
class AdamP(Optimizer):
r"""Implements AdamP algorithm.
It has been proposed in `Slowing Down the Weight Norm Increase in
Momentum-based Optimizers`
https://arxiv.org/abs/2006.08217
Note:
Reference code: https://github.com/clovaai/AdamP
"""
def __init__(
self,
params,
lr: float = 1e-3,
betas = (0.9, 0.999),
eps: float = 1e-8,
weight_decay: float = 0,
delta: float = 0.1,
wd_ratio: float = 0.1,
nesterov: bool = False,
) -> None:
if lr <= 0.0:
raise ValueError("Invalid learning rate: {}".format(lr))
if eps < 0.0:
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 weight_decay < 0:
raise ValueError(
"Invalid weight_decay value: {}".format(weight_decay)
)
if delta < 0:
raise ValueError("Invalid delta value: {}".format(delta))
if wd_ratio < 0:
raise ValueError("Invalid wd_ratio value: {}".format(wd_ratio))
defaults = dict(
lr=lr,
betas=betas,
eps=eps,
weight_decay=weight_decay,
delta=delta,
wd_ratio=wd_ratio,
nesterov=nesterov,
)
super(AdamP, self).__init__(params, defaults)
@staticmethod
def _channel_view(x):
return x.view(x.size(0), -1)
@staticmethod
def _layer_view(x):
return x.view(1, -1)
@staticmethod
def _cosine_similarity(x, y, eps, view_func):
x = view_func(x)
y = view_func(y)
x_norm = x.norm(dim=1).add_(eps)
y_norm = y.norm(dim=1).add_(eps)
dot = (x * y).sum(dim=1)
return dot.abs() / x_norm / y_norm
def _projection(self, p, grad, perturb, delta, wd_ratio, eps):
wd = 1
expand_size = [-1] + [1] * (len(p.shape) - 1)
for view_func in [self._channel_view, self._layer_view]:
cosine_sim = self._cosine_similarity(grad, p.data, eps, view_func)
if cosine_sim.max() < delta / math.sqrt(view_func(p.data).size(1)):
p_n = p.data / view_func(p.data).norm(dim=1).view(
expand_size
).add_(eps)
perturb -= p_n * view_func(p_n * perturb).sum(dim=1).view(
expand_size
)
wd = wd_ratio
return perturb, wd
return perturb, wd
def step(self, closure = None):
r"""Performs a single optimization step.
Arguments:
closure: A closure that reevaluates the model and returns the loss.
"""
loss = None
if closure is not None:
loss = closure()
for group in self.param_groups:
for p in group["params"]:
if p.grad is None:
continue
grad = p.grad.data
beta1, beta2 = group["betas"]
nesterov = group["nesterov"]
state = self.state[p]
# State initialization
if len(state) == 0:
state["step"] = 0
state["exp_avg"] = torch.zeros_like(
p.data, memory_format=torch.preserve_format
)
state["exp_avg_sq"] = torch.zeros_like(
p.data, memory_format=torch.preserve_format
)
# Adam
exp_avg, exp_avg_sq = state["exp_avg"], state["exp_avg_sq"]
state["step"] += 1
bias_correction1 = 1 - beta1 ** state["step"]
bias_correction2 = 1 - beta2 ** state["step"]
exp_avg.mul_(beta1).add_(grad, alpha=1 - beta1)
exp_avg_sq.mul_(beta2).addcmul_(grad, grad, value=1 - beta2)
denom = (exp_avg_sq.sqrt() / math.sqrt(bias_correction2)).add_(
group["eps"]
)
step_size = group["lr"] / bias_correction1
if nesterov:
perturb = (beta1 * exp_avg + (1 - beta1) * grad) / denom
else:
perturb = exp_avg / denom
# Projection
wd_ratio = 1
if len(p.shape) > 1:
perturb, wd_ratio = self._projection(
p,
grad,
perturb,
group["delta"],
group["wd_ratio"],
group["eps"],
)
# Weight decay
if group["weight_decay"] > 0:
p.data.mul_(
1 - group["lr"] * group["weight_decay"] * wd_ratio
)
# Step
p.data.add_(perturb, alpha=-step_size)
return loss |