# codes in this file are reproduced from https://github.com/microsoft/nni with some changes.
import torch
import torch.nn as nn
import logging
from .base import BaseNAS
from ..space import (
BaseSpace,
replace_layer_choice,
replace_input_choice,
get_module_order,
sort_replaced_module,
PathSamplingInputChoice,
PathSamplingLayerChoice,
apply_fixed_architecture,
)
from tqdm import tqdm
from datetime import datetime
import numpy as np
from .rl_utils import ReinforceController, ReinforceField
LOGGER = logging.getLogger(__name__)
[docs]class RL(BaseNAS):
"""
RL in GraphNas.
Parameters
----------
num_epochs : int
Number of epochs planned for training.
device : torch.device
``torch.device("cpu")`` or ``torch.device("cuda")``.
log_frequency : int
Step count per logging.
grad_clip : float
Gradient clipping. Set to 0 to disable. Default: 5.
entropy_weight : float
Weight of sample entropy loss.
skip_weight : float
Weight of skip penalty loss.
baseline_decay : float
Decay factor of baseline. New baseline will be equal to ``baseline_decay * baseline_old + reward * (1 - baseline_decay)``.
ctrl_lr : float
Learning rate for RL controller.
ctrl_steps_aggregate : int
Number of steps that will be aggregated into one mini-batch for RL controller.
ctrl_steps : int
Number of mini-batches for each epoch of RL controller learning.
ctrl_kwargs : dict
Optional kwargs that will be passed to :class:`ReinforceController`.
n_warmup : int
Number of epochs for training super network.
model_lr : float
Learning rate for super network.
model_wd : float
Weight decay for super network.
disable_progress: boolean
Control whether show the progress bar.
"""
def __init__(
self,
num_epochs=5,
device="auto",
log_frequency=None,
grad_clip=5.0,
entropy_weight=0.0001,
skip_weight=0.8,
baseline_decay=0.999,
ctrl_lr=0.00035,
ctrl_steps_aggregate=20,
ctrl_kwargs=None,
n_warmup=100,
model_lr=5e-3,
model_wd=5e-4,
disable_progress=False,
weight_share=True,
):
super().__init__(device)
self.num_epochs = num_epochs
self.log_frequency = log_frequency
self.entropy_weight = entropy_weight
self.skip_weight = skip_weight
self.baseline_decay = baseline_decay
self.baseline = 0.0
self.ctrl_steps_aggregate = ctrl_steps_aggregate
self.grad_clip = grad_clip
self.ctrl_kwargs = ctrl_kwargs
self.ctrl_lr = ctrl_lr
self.n_warmup = n_warmup
self.model_lr = model_lr
self.model_wd = model_wd
self.disable_progress = disable_progress
self.weight_share = weight_share
[docs] def search(self, space: BaseSpace, dset, estimator):
self.model = space
self.dataset = dset # .to(self.device)
self.estimator = estimator
# replace choice
self.nas_modules = []
k2o = get_module_order(self.model)
replace_layer_choice(self.model, PathSamplingLayerChoice, self.nas_modules)
replace_input_choice(self.model, PathSamplingInputChoice, self.nas_modules)
self.nas_modules = sort_replaced_module(k2o, self.nas_modules)
# to device
self.model = self.model.to(self.device)
# fields
self.nas_fields = [
ReinforceField(
name,
len(module),
isinstance(module, PathSamplingLayerChoice) or module.n_chosen == 1,
)
for name, module in self.nas_modules
]
self.controller = ReinforceController(
self.nas_fields, **(self.ctrl_kwargs or {})
)
self.ctrl_optim = torch.optim.Adam(
self.controller.parameters(), lr=self.ctrl_lr
)
# train
with tqdm(range(self.num_epochs), disable=self.disable_progress) as bar:
for i in bar:
l2 = self._train_controller(i)
bar.set_postfix(reward_controller=l2)
selection = self.export()
arch = space.parse_model(selection)
return arch
def _train_controller(self, epoch):
self.model.eval()
self.controller.train()
self.ctrl_optim.zero_grad()
rewards = []
with tqdm(
range(self.ctrl_steps_aggregate), disable=self.disable_progress
) as bar:
for ctrl_step in bar:
self._resample()
metric, loss = self._infer(mask="val")
reward = metric["acc"]
bar.set_postfix(loss=loss.item(), **metric)
LOGGER.debug(f"{self.selection}\n{metric},{loss}")
rewards.append(reward)
if self.entropy_weight:
reward += (
self.entropy_weight * self.controller.sample_entropy.item()
)
self.baseline = self.baseline * self.baseline_decay + reward * (
1 - self.baseline_decay
)
loss = self.controller.sample_log_prob * (reward - self.baseline)
if self.skip_weight:
loss += self.skip_weight * self.controller.sample_skip_penalty
loss /= self.ctrl_steps_aggregate
loss.backward()
if (ctrl_step + 1) % self.ctrl_steps_aggregate == 0:
if self.grad_clip > 0:
nn.utils.clip_grad_norm_(
self.controller.parameters(), self.grad_clip
)
self.ctrl_optim.step()
self.ctrl_optim.zero_grad()
if (
self.log_frequency is not None
and ctrl_step % self.log_frequency == 0
):
LOGGER.debug(
"RL Epoch [%d/%d] Step [%d/%d] %s",
epoch + 1,
self.num_epochs,
ctrl_step + 1,
self.ctrl_steps_aggregate,
)
return sum(rewards) / len(rewards)
def _resample(self):
result = self.controller.resample()
if self.weight_share:
for name, module in self.nas_modules:
module.sampled = result[name]
else:
self.arch = self.model.parse_model(result)
self.selection = result
def export(self):
self.controller.eval()
with torch.no_grad():
return self.controller.resample()
def _infer(self, mask="train"):
if self.weight_share:
metric, loss = self.estimator.infer(self.model, self.dataset, mask=mask)
else:
metric, loss = self.estimator.infer(
self.arch._model, self.dataset, mask=mask
)
return metric, loss