import sys
import os
import argparse
import time
import random
import math
import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.autograd import Variable
import cuda_functional as MF
def read_corpus(path, eos="</s>"):
data = [ ]
with open(path) as fin:
for line in fin:
data += line.split() + [ eos ]
return data
def create_batches(data_text, map_to_ids, batch_size, cuda=True):
data_ids = map_to_ids(data_text)
N = len(data_ids)
L = ((N-1) // batch_size) * batch_size
x = np.copy(data_ids[:L].reshape(batch_size,-1).T)
y = np.copy(data_ids[1:L+1].reshape(batch_size,-1).T)#x和y的结果基本相同
x, y = torch.from_numpy(x), torch.from_numpy(y)
x, y = x.contiguous(), y.contiguous()
if cuda:
x, y = x.cuda(), y.cuda()
return x, y
class EmbeddingLayer(nn.Module):#为语料中每一个单词对应的其相应的词向量
def __init__(self, n_d, words, fix_emb=False):
super(EmbeddingLayer, self).__init__()
word2id = {}
for w in words:
if w not in word2id:
word2id[w] = len(word2id)#把文本映射到数字上。
self.word2id = word2id
self.n_V, self.n_d = len(word2id), n_d#n_V应该是指词库大小，n_d指hidden state size
self.embedding = nn.Embedding(self.n_V, n_d)#赋予每个单词相应的词向量
def forward(self, x):
return self.embedding(x)
def map_to_ids(self, text):#映射
return np.asarray([self.word2id[x] for x in text],
dtype='int64'
)
class Model(nn.Module):
def __init__(self, words, args):
super(Model, self).__init__()
self.args = args
self.n_d = args.d
self.depth = args.depth
self.drop = nn.Dropout(args.dropout)#防止过拟合的层，变分dropout
self.embedding_layer = EmbeddingLayer(self.n_d, words)
self.n_V = self.embedding_layer.n_V
if args.lstm:
self.rnn = nn.LSTM(self.n_d, self.n_d,#self.rnn = nn.LSTM( # if use nn.RNN(), it hardly learns
input_size=INPUT_SIZE,
hidden_size=64, # rnn hidden unit
num_layers=1, # number of rnn layer
batch_first=True, # input & output will has batch size as 1s dimension. e.g. (batch, time_step, input_size)
)
self.depth,
dropout = args.rnn_dropout
)
else:
self.rnn = MF.SRU(self.n_d, self.n_d, self.depth,
dropout = args.rnn_dropout,
rnn_dropout = args.rnn_dropout,
use_tanh = 0
)
self.output_layer = nn.Linear(self.n_d, self.n_V)
# tie weights
self.output_layer.weight = self.embedding_layer.embedding.weight
self.init_weights()
if not args.lstm:
self.rnn.set_bias(args.bias)
def init_weights(self):#initial c
val_range = (3.0/self.n_d)**0.5
for p in self.parameters():
if p.dim() > 1: # matrix
p.data.uniform_(-val_range, val_range)
else:
p.data.zero_()
def forward(self, x, hidden):
emb = self.drop(self.embedding_layer(x))
output, hidden = self.rnn(emb, hidden)#rnn的输入和输出都有两个，即输入和上一层的隐层的值
output = self.drop(output)
output = output.view(-1, output.size(2))#改变tensor的size，size（2）表示计算第三维的大小，如size 4x6x7，则.size(3)就等于7
output = self.output_layer(output)
return output, hidden
def init_hidden(self, batch_size):
weight = next(self.parameters()).data
zeros = Variable(weight.new(self.depth, batch_size, self.n_d).zero_())
if self.args.lstm:
return (zeros, zeros)
else:
return zeros
def print_pnorm(self):#输出范数，范数常常被用来度量某个向量空间（或矩阵）中的每个向量的长度或大小。正则化中就是用范数
norms = [ "{:.0f}".format(x.norm().data[0]) for x in self.parameters() ]
sys.stdout.write("\tp_norm: {}\n".format(
norms
))
def train_model(epoch, model, train):
model.train()
args = model.args
unroll_size = args.unroll_size
batch_size = args.batch_size
N = (len(train[0])-1)//unroll_size + 1
lr = args.lr
total_loss = 0.0
criterion = nn.CrossEntropyLoss(size_average=False)#每个小批次的损失将被相加。
hidden = model.init_hidden(batch_size)
for i in range(N):
x = train[0][i*unroll_size:(i+1)*unroll_size]
y = train[1][i*unroll_size:(i+1)*unroll_size].view(-1)#view(-1)是指按列展开
x, y = Variable(x), Variable(y)
hidden = (Variable(hidden[0].data), Variable(hidden[1].data)) if args.lstm \
else Variable(hidden.data)
model.zero_grad()
output, hidden = model(x, hidden)
assert x.size(1) == batch_size
loss = criterion(output, y) / x.size(1)#.size(1)计算列数.size(0)计算行数，must be (1. nn output, 2. target), the target label is NOT one-hotted
loss.backward()
torch.nn.utils.clip_grad_norm(model.parameters(), args.clip_grad)#nn.utils.clip_grad_norm()对网络进行梯度裁剪，因为RNN中容易出现梯度爆炸的问题。
for p in model.parameters():
if p.requires_grad:
if args.weight_decay > 0:
p.data.mul_(1.0-args.weight_decay)
p.data.add_(-lr, p.grad.data)
if math.isnan(loss.data[0]) or math.isinf(loss.data[0]):#如果发生梯度消失或梯度爆炸则退出程序
sys.exit(0) #math.isinf(x)：如果x = ±inf（inf：infinity ，译为无穷）也就是±∞返回True
return #math.isnan(x）：如果x = Non (not a number) 返回True；
total_loss += loss.data[0] / x.size(0)
if i%10 == 0:
sys.stdout.write("\r{}".format(i))
sys.stdout.flush()
return np.exp(total_loss/N)
def eval_model(model, valid):
model.eval()
args = model.args
total_loss = 0.0
unroll_size = model.args.unroll_size
criterion = nn.CrossEntropyLoss(size_average=False)
hidden = model.init_hidden(1)
N = (len(valid[0])-1)//unroll_size + 1
for i in range(N):
x = valid[0][i*unroll_size:(i+1)*unroll_size]
y = valid[1][i*unroll_size:(i+1)*unroll_size].view(-1)
x, y = Variable(x, volatile=True), Variable(y)
hidden = (Variable(hidden[0].data), Variable(hidden[1].data)) if args.lstm \
else Variable(hidden.data)
output, hidden = model(x, hidden)
loss = criterion(output, y)
total_loss += loss.data[0]
avg_loss = total_loss / valid[1].numel()#numel()返回张量所含元素的个数
ppl = np.exp(avg_loss)
return ppl
def main(args):
train = read_corpus(args.train)
dev = read_corpus(args.dev)
test = read_corpus(args.test)
model = Model(train, args)
model.cuda()
sys.stdout.write("vocab size: {}\n".format(
model.embedding_layer.n_V
))
sys.stdout.write("num of parameters: {}\n".format(
sum(x.numel() for x in model.parameters() if x.requires_grad)
))
model.print_pnorm()
sys.stdout.write("\n")
map_to_ids = model.embedding_layer.map_to_ids
train = create_batches(train, map_to_ids, args.batch_size)
dev = create_batches(dev, map_to_ids, 1)
test = create_batches(test, map_to_ids, 1)
unchanged = 0
best_dev = 1e+8
for epoch in range(args.max_epoch):
start_time = time.time()#返回当前时间的时间戳（1970纪元后经过的浮点秒数）。
if args.lr_decay_epoch>0 and epoch>=args.lr_decay_epoch:
args.lr *= args.lr_decay
train_ppl = train_model(epoch, model, train)
dev_ppl = eval_model(model, dev)
sys.stdout.write("\rEpoch={} lr={:.4f} train_ppl={:.2f} dev_ppl={:.2f}"
"\t[{:.2f}m]\n".format(
epoch,
args.lr,
train_ppl,
dev_ppl,
(time.time()-start_time)/60.0
))
model.print_pnorm()
sys.stdout.flush()
if dev_ppl < best_dev:
unchanged = 0
best_dev = dev_ppl
start_time = time.time()
test_ppl = eval_model(model, test)
sys.stdout.write("\t[eval] test_ppl={:.2f}\t[{:.2f}m]\n".format(
test_ppl,
(time.time()-start_time)/60.0
))
sys.stdout.flush()
else:
unchanged += 1
if unchanged >= 30: break
sys.stdout.write("\n")
if __name__ == "__main__":
argparser = argparse.ArgumentParser(sys.argv[0], conflict_handler='resolve')
argparser.add_argument("--lstm", action="store_true")
argparser.add_argument("--train", type=str, required=True, help="training file")
argparser.add_argument("--dev", type=str, required=True, help="dev file")
argparser.add_argument("--test", type=str, required=True, help="test file")
argparser.add_argument("--batch_size", "--batch", type=int, default=32)
argparser.add_argument("--unroll_size", type=int, default=35)
argparser.add_argument(" ", type=int, default=300)
argparser.add_argument("--d", type=int, default=910)
argparser.add_argument("--dropout", type=float, default=0.7,
help="dropout of word embeddings and softmax output"
)
argparser.add_argument("--rnn_dropout", type=float, default=0.2,
help="dropout of RNN layers"
)
argparser.add_argument("--bias", type=float, default=-3,
help="intial bias of highway gates",
)
argparser.add_argument("--depth", type=int, default=6)
argparser.add_argument("--lr", type=float, default=1.0)
argparser.add_argument("--lr_decay", type=float, default=0.98)
argparser.add_argument("--lr_decay_epoch", type=int, default=175)
argparser.add_argument("--weight_decay", type=float, default=1e-5)
argparser.add_argument("--clip_grad", type=float, default=5)
args = argparser.parse_args()
print (args)
