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# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2019 #
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# modified from https://github.com/pytorch/examples/blob/master/reinforcement_learning/reinforce.py #
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import os, sys, time, glob, random, argparse
import numpy as np, collections
from copy import deepcopy
from pathlib import Path
import torch
import torch.nn as nn
from torch.distributions import Categorical
lib_dir = (Path(__file__).parent / '..' / '..' / 'lib').resolve()
if str(lib_dir) not in sys.path: sys.path.insert(0, str(lib_dir))
from config_utils import load_config, dict2config, configure2str
from datasets import get_datasets, SearchDataset
from procedures import prepare_seed, prepare_logger, save_checkpoint, copy_checkpoint, get_optim_scheduler
from utils import get_model_infos, obtain_accuracy
from log_utils import AverageMeter, time_string, convert_secs2time
from nas_201_api import NASBench201API as API
from models import CellStructure, get_search_spaces
from R_EA import train_and_eval
class Policy(nn.Module):
def __init__(self, max_nodes, search_space):
super(Policy, self).__init__()
self.max_nodes = max_nodes
self.search_space = deepcopy(search_space)
self.edge2index = {}
for i in range(1, max_nodes):
for j in range(i):
node_str = '{:}<-{:}'.format(i, j)
self.edge2index[ node_str ] = len(self.edge2index)
self.arch_parameters = nn.Parameter( 1e-3*torch.randn(len(self.edge2index), len(search_space)) )
def generate_arch(self, actions):
genotypes = []
for i in range(1, self.max_nodes):
xlist = []
for j in range(i):
node_str = '{:}<-{:}'.format(i, j)
op_name = self.search_space[ actions[ self.edge2index[ node_str ] ] ]
xlist.append((op_name, j))
genotypes.append( tuple(xlist) )
return CellStructure( genotypes )
def genotype(self):
genotypes = []
for i in range(1, self.max_nodes):
xlist = []
for j in range(i):
node_str = '{:}<-{:}'.format(i, j)
with torch.no_grad():
weights = self.arch_parameters[ self.edge2index[node_str] ]
op_name = self.search_space[ weights.argmax().item() ]
xlist.append((op_name, j))
genotypes.append( tuple(xlist) )
return CellStructure( genotypes )
def forward(self):
alphas = nn.functional.softmax(self.arch_parameters, dim=-1)
return alphas
class ExponentialMovingAverage(object):
"""Class that maintains an exponential moving average."""
def __init__(self, momentum):
self._numerator = 0
self._denominator = 0
self._momentum = momentum
def update(self, value):
self._numerator = self._momentum * self._numerator + (1 - self._momentum) * value
self._denominator = self._momentum * self._denominator + (1 - self._momentum)
def value(self):
"""Return the current value of the moving average"""
return self._numerator / self._denominator
def select_action(policy):
probs = policy()
m = Categorical(probs)
action = m.sample()
#policy.saved_log_probs.append(m.log_prob(action))
return m.log_prob(action), action.cpu().tolist()
def main(xargs, nas_bench):
assert torch.cuda.is_available(), 'CUDA is not available.'
torch.backends.cudnn.enabled = True
torch.backends.cudnn.benchmark = False
torch.backends.cudnn.deterministic = True
torch.set_num_threads( xargs.workers )
prepare_seed(xargs.rand_seed)
logger = prepare_logger(args)
if xargs.dataset == 'cifar10':
dataname = 'cifar10-valid'
else:
dataname = xargs.dataset
if xargs.data_path is not None:
train_data, valid_data, xshape, class_num = get_datasets(xargs.dataset, xargs.data_path, -1)
split_Fpath = 'configs/nas-benchmark/cifar-split.txt'
cifar_split = load_config(split_Fpath, None, None)
train_split, valid_split = cifar_split.train, cifar_split.valid
logger.log('Load split file from {:}'.format(split_Fpath))
config_path = 'configs/nas-benchmark/algos/R-EA.config'
config = load_config(config_path, {'class_num': class_num, 'xshape': xshape}, logger)
# To split data
train_data_v2 = deepcopy(train_data)
train_data_v2.transform = valid_data.transform
valid_data = train_data_v2
search_data = SearchDataset(xargs.dataset, train_data, train_split, valid_split)
# data loader
train_loader = torch.utils.data.DataLoader(train_data, batch_size=config.batch_size, sampler=torch.utils.data.sampler.SubsetRandomSampler(train_split) , num_workers=xargs.workers, pin_memory=True)
valid_loader = torch.utils.data.DataLoader(valid_data, batch_size=config.batch_size, sampler=torch.utils.data.sampler.SubsetRandomSampler(valid_split), num_workers=xargs.workers, pin_memory=True)
logger.log('||||||| {:10s} ||||||| Train-Loader-Num={:}, Valid-Loader-Num={:}, batch size={:}'.format(xargs.dataset, len(train_loader), len(valid_loader), config.batch_size))
logger.log('||||||| {:10s} ||||||| Config={:}'.format(xargs.dataset, config))
extra_info = {'config': config, 'train_loader': train_loader, 'valid_loader': valid_loader}
else:
config_path = 'configs/nas-benchmark/algos/R-EA.config'
config = load_config(config_path, None, logger)
extra_info = {'config': config, 'train_loader': None, 'valid_loader': None}
logger.log('||||||| {:10s} ||||||| Config={:}'.format(xargs.dataset, config))
search_space = get_search_spaces('cell', xargs.search_space_name)
policy = Policy(xargs.max_nodes, search_space)
optimizer = torch.optim.Adam(policy.parameters(), lr=xargs.learning_rate)
#optimizer = torch.optim.SGD(policy.parameters(), lr=xargs.learning_rate)
eps = np.finfo(np.float32).eps.item()
baseline = ExponentialMovingAverage(xargs.EMA_momentum)
logger.log('policy : {:}'.format(policy))
logger.log('optimizer : {:}'.format(optimizer))
logger.log('eps : {:}'.format(eps))
# nas dataset load
logger.log('{:} use nas_bench : {:}'.format(time_string(), nas_bench))
# REINFORCE
# attempts = 0
x_start_time = time.time()
logger.log('Will start searching with time budget of {:} s.'.format(xargs.time_budget))
total_steps, total_costs, trace = 0, 0, []
#for istep in range(xargs.RL_steps):
while total_costs < xargs.time_budget:
start_time = time.time()
log_prob, action = select_action( policy )
arch = policy.generate_arch( action )
reward, cost_time = train_and_eval(arch, nas_bench, extra_info, dataname)
trace.append( (reward, arch) )
# accumulate time
if total_costs + cost_time < xargs.time_budget:
total_costs += cost_time
else: break
baseline.update(reward)
# calculate loss
policy_loss = ( -log_prob * (reward - baseline.value()) ).sum()
optimizer.zero_grad()
policy_loss.backward()
optimizer.step()
# accumulate time
total_costs += time.time() - start_time
total_steps += 1
logger.log('step [{:3d}] : average-reward={:.3f} : policy_loss={:.4f} : {:}'.format(total_steps, baseline.value(), policy_loss.item(), policy.genotype()))
#logger.log('----> {:}'.format(policy.arch_parameters))
#logger.log('')
# best_arch = policy.genotype() # first version
best_arch = max(trace, key=lambda x: x[0])[1]
logger.log('REINFORCE finish with {:} steps and {:.1f} s (real cost={:.3f}).'.format(total_steps, total_costs, time.time()-x_start_time))
info = nas_bench.query_by_arch(best_arch, '200')
if info is None: logger.log('Did not find this architecture : {:}.'.format(best_arch))
else : logger.log('{:}'.format(info))
logger.log('-'*100)
logger.close()
return logger.log_dir, nas_bench.query_index_by_arch( best_arch )
if __name__ == '__main__':
parser = argparse.ArgumentParser("The REINFORCE Algorithm")
parser.add_argument('--data_path', type=str, help='Path to dataset')
parser.add_argument('--dataset', type=str, choices=['cifar10', 'cifar100', 'ImageNet16-120'], help='Choose between Cifar10/100 and ImageNet-16.')
# channels and number-of-cells
parser.add_argument('--search_space_name', type=str, help='The search space name.')
parser.add_argument('--max_nodes', type=int, help='The maximum number of nodes.')
parser.add_argument('--channel', type=int, help='The number of channels.')
parser.add_argument('--num_cells', type=int, help='The number of cells in one stage.')
parser.add_argument('--learning_rate', type=float, help='The learning rate for REINFORCE.')
#parser.add_argument('--RL_steps', type=int, help='The steps for REINFORCE.')
parser.add_argument('--EMA_momentum', type=float, help='The momentum value for EMA.')
parser.add_argument('--time_budget', type=int, help='The total time cost budge for searching (in seconds).')
# log
parser.add_argument('--workers', type=int, default=2, help='number of data loading workers (default: 2)')
parser.add_argument('--save_dir', type=str, help='Folder to save checkpoints and log.')
parser.add_argument('--arch_nas_dataset', type=str, help='The path to load the architecture dataset (tiny-nas-benchmark).')
parser.add_argument('--print_freq', type=int, help='print frequency (default: 200)')
parser.add_argument('--rand_seed', type=int, default=-1, help='manual seed')
args = parser.parse_args()
#if args.rand_seed is None or args.rand_seed < 0: args.rand_seed = random.randint(1, 100000)
if args.arch_nas_dataset is None or not os.path.isfile(args.arch_nas_dataset):
nas_bench = None
else:
print ('{:} build NAS-Benchmark-API from {:}'.format(time_string(), args.arch_nas_dataset))
nas_bench = API(args.arch_nas_dataset)
if args.rand_seed < 0:
save_dir, all_indexes, num = None, [], 500
for i in range(num):
print ('{:} : {:03d}/{:03d}'.format(time_string(), i, num))
args.rand_seed = random.randint(1, 100000)
save_dir, index = main(args, nas_bench)
all_indexes.append( index )
torch.save(all_indexes, save_dir / 'results.pth')
else:
main(args, nas_bench)