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maligan_instructor.py
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# -*- coding: utf-8 -*-
# @Author : William
# @Project : TextGAN-william
# @FileName : maligan_instructor.py
# @Time : Created at 2019/11/29
# @Blog : http://zhiweil.ml/
# @Description :
# Copyrights (C) 2018. All Rights Reserved.
import torch
import torch.nn.functional as F
import torch.optim as optim
import config as cfg
from instructor.real_data.instructor import BasicInstructor
from models.MaliGAN_D import MaliGAN_D
from models.MaliGAN_G import MaliGAN_G
from utils.data_loader import GenDataIter, DisDataIter
# noinspection PyUnresolvedReferences
class MaliGANInstructor(BasicInstructor):
def __init__(self, opt):
super(MaliGANInstructor, self).__init__(opt)
# generator, discriminator
self.gen = MaliGAN_G(cfg.gen_embed_dim, cfg.gen_hidden_dim, cfg.vocab_size, cfg.max_seq_len,
cfg.padding_idx, gpu=cfg.CUDA)
self.dis = MaliGAN_D(cfg.dis_embed_dim, cfg.vocab_size, cfg.padding_idx, gpu=cfg.CUDA)
self.init_model()
# Optimizer
self.gen_opt = optim.Adam(self.gen.parameters(), lr=cfg.gen_lr)
self.gen_adv_opt = optim.Adam(self.gen.parameters(), lr=cfg.gen_lr)
self.dis_opt = optim.Adam(self.dis.parameters(), lr=cfg.dis_lr)
def _run(self):
# ===PRE-TRAINING===
# TRAIN GENERATOR
if not cfg.gen_pretrain:
self.log.info('Starting Generator MLE Training...')
self.pretrain_generator(cfg.MLE_train_epoch)
if cfg.if_save and not cfg.if_test:
torch.save(self.gen.state_dict(), cfg.pretrained_gen_path)
print('Save pre-trained generator: {}'.format(cfg.pretrained_gen_path))
# ===TRAIN DISCRIMINATOR====
if not cfg.dis_pretrain:
self.log.info('Starting Discriminator Training...')
self.train_discriminator(cfg.d_step, cfg.d_epoch)
if cfg.if_save and not cfg.if_test:
torch.save(self.dis.state_dict(), cfg.pretrained_dis_path)
print('Save pre-trained discriminator: {}'.format(cfg.pretrained_dis_path))
# ===ADVERSARIAL TRAINING===
self.log.info('Starting Adversarial Training...')
self.log.info('Initial generator: %s' % (self.cal_metrics(fmt_str=True)))
for adv_epoch in range(cfg.ADV_train_epoch):
self.log.info('-----\nADV EPOCH %d\n-----' % adv_epoch)
self.sig.update()
if self.sig.adv_sig:
self.adv_train_generator(cfg.ADV_g_step) # Generator
self.train_discriminator(cfg.ADV_d_step, cfg.ADV_d_epoch, 'ADV') # Discriminator
if adv_epoch % cfg.adv_log_step == 0 or adv_epoch == cfg.ADV_train_epoch - 1:
if cfg.if_save and not cfg.if_test:
self._save('ADV', adv_epoch)
else:
self.log.info('>>> Stop by adv_signal! Finishing adversarial training...')
break
def _test(self):
print('>>> Begin test...')
self._run()
pass
def pretrain_generator(self, epochs):
"""
Max Likelihood Pre-training for the generator
"""
for epoch in range(epochs):
self.sig.update()
if self.sig.pre_sig:
pre_loss = self.train_gen_epoch(self.gen, self.train_data.loader, self.mle_criterion, self.gen_opt)
# ===Test===
if epoch % cfg.pre_log_step == 0 or epoch == epochs - 1:
self.log.info(
'[MLE-GEN] epoch %d : pre_loss = %.4f, %s' % (epoch, pre_loss, self.cal_metrics(fmt_str=True)))
if cfg.if_save and not cfg.if_test:
self._save('MLE', epoch)
else:
self.log.info('>>> Stop by pre signal, skip to adversarial training...')
break
def adv_train_generator(self, g_step):
"""
The gen is trained by MLE-like objective.
"""
total_g_loss = 0
for step in range(g_step):
inp, target = GenDataIter.prepare(self.gen.sample(cfg.batch_size, cfg.batch_size), gpu=cfg.CUDA)
# ===Train===
rewards = self.get_mali_reward(target)
adv_loss = self.gen.adv_loss(inp, target, rewards)
self.optimize(self.gen_adv_opt, adv_loss)
total_g_loss += adv_loss.item()
# ===Test===
self.log.info('[ADV-GEN]: g_loss = %.4f, %s' % (total_g_loss, self.cal_metrics(fmt_str=True)))
def train_discriminator(self, d_step, d_epoch, phase='MLE'):
"""
Training the discriminator on real_data_samples (positive) and generated samples from gen (negative).
Samples are drawn d_step times, and the discriminator is trained for d_epoch d_epoch.
"""
# prepare loader for validate
global d_loss, train_acc
for step in range(d_step):
# prepare loader for training
pos_samples = self.train_data.target # not re-sample the Oracle data
neg_samples = self.gen.sample(cfg.samples_num, 4 * cfg.batch_size)
dis_data = DisDataIter(pos_samples, neg_samples)
for epoch in range(d_epoch):
# ===Train===
d_loss, train_acc = self.train_dis_epoch(self.dis, dis_data.loader, self.dis_criterion,
self.dis_opt)
# ===Test===
self.log.info('[%s-DIS] d_step %d: d_loss = %.4f, train_acc = %.4f,' % (
phase, step, d_loss, train_acc))
if cfg.if_save and not cfg.if_test:
torch.save(self.dis.state_dict(), cfg.pretrained_dis_path)
def get_mali_reward(self, samples):
rewards = []
for _ in range(cfg.rollout_num):
dis_out = F.softmax(self.dis(samples), dim=-1)[:, 1]
rewards.append(dis_out)
rewards = torch.mean(torch.stack(rewards, dim=0), dim=0) # batch_size
rewards = torch.div(rewards, 1 - rewards)
rewards = torch.div(rewards, torch.sum(rewards))
rewards -= torch.mean(rewards)
rewards = rewards.unsqueeze(1).expand(samples.size()) # batch_size * seq_len
return rewards