Source code for lmflow.optim.radam
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import math
import warnings
import torch
from torch.optim.optimizer import Optimizer
[docs]
class RAdam(Optimizer):
r"""Implements RAdam optimization algorithm.
Note:
Deprecated, please use version provided by PyTorch_.
It has been proposed in `On the Variance of the Adaptive Learning
Rate and Beyond`.
https://arxiv.org/abs/1908.03265
Note:
Reference code: https://github.com/LiyuanLucasLiu/RAdam
"""
def __init__(
self,
params,
lr: float = 1e-3,
betas = (0.9, 0.999),
eps: float = 1e-8,
weight_decay: float = 0,
) -> None:
warnings.warn(
"RAdam optimizer is deprecated, since it is included "
"in pytorch natively.",
DeprecationWarning,
stacklevel=2,
)
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 (
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,
buffer=[[None, None, None] for _ in range(10)],
)
super(RAdam, self).__init__(params, defaults)
[docs]
def __setstate__(self, state):
super(RAdam, self).__setstate__(state)
[docs]
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:
lr = group["lr"]
weight_decay = group["weight_decay"]
beta1, beta2 = group["betas"]
eps = group["eps"]
for p in group["params"]:
if p.grad is None:
continue
grad = p.grad.data.float()
if grad.is_sparse:
msg = (
"RAdam does not support sparse gradients, "
"please consider SparseAdam instead"
)
raise RuntimeError(msg)
p_data_fp32 = p.data.float()
state = self.state[p]
if len(state) == 0:
state["step"] = 0
state["exp_avg"] = torch.zeros_like(
p_data_fp32, memory_format=torch.preserve_format
)
state["exp_avg_sq"] = torch.zeros_like(
p_data_fp32, memory_format=torch.preserve_format
)
else:
state["exp_avg"] = state["exp_avg"].type_as(p_data_fp32)
state["exp_avg_sq"] = state["exp_avg_sq"].type_as(
p_data_fp32
)
exp_avg, exp_avg_sq = state["exp_avg"], state["exp_avg_sq"]
exp_avg_sq.mul_(beta2).addcmul_(grad, grad, value=1 - beta2)
exp_avg.mul_(beta1).add_(grad, alpha=1 - beta1)
state["step"] += 1
buffered = group["buffer"][int(state["step"] % 10)]
if state["step"] == buffered[0]:
N_sma, step_size = buffered[1], buffered[2]
else:
buffered[0] = state["step"]
beta2_t = beta2 ** state["step"]
N_sma_max = 2 / (1 - beta2) - 1
N_sma = N_sma_max - 2 * state["step"] * beta2_t / (
1 - beta2_t
)
buffered[1] = N_sma
# more conservative since it's an approximated value
if N_sma >= 5:
step_size = (
lr
* math.sqrt(
(1 - beta2_t)
* (N_sma - 4)
/ (N_sma_max - 4)
* (N_sma - 2)
/ N_sma
* N_sma_max
/ (N_sma_max - 2)
)
/ (1 - beta1 ** state["step"])
)
else:
step_size = lr / (1 - beta1 ** state["step"])
buffered[2] = step_size
if weight_decay != 0:
p_data_fp32.add_(p_data_fp32, alpha=-weight_decay * lr)
# more conservative since it's an approximated value
if N_sma >= 5:
denom = exp_avg_sq.sqrt().add_(eps)
p_data_fp32.addcdiv_(exp_avg, denom, value=-step_size)
else:
p_data_fp32.add_(exp_avg, alpha=-step_size)
p.data.copy_(p_data_fp32)
return loss