1125de1 Jan 18, 2017
@nealwu @itsmeolivia @mrphoenix13
535 lines (450 sloc) 19.3 KB
# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Multi-threaded word2vec mini-batched skip-gram model.
Trains the model described in:
(Mikolov, et. al.) Efficient Estimation of Word Representations in Vector Space
ICLR 2013.
This model does traditional minibatching.
The key ops used are:
* placeholder for feeding in tensors for each example.
* embedding_lookup for fetching rows from the embedding matrix.
* sigmoid_cross_entropy_with_logits to calculate the loss.
* GradientDescentOptimizer for optimizing the loss.
* skipgram custom op that does input processing.
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import os
import sys
import threading
import time
from six.moves import xrange # pylint: disable=redefined-builtin
import numpy as np
import tensorflow as tf
word2vec = tf.load_op_library(os.path.join(os.path.dirname(os.path.realpath(__file__)), ''))
flags =
flags.DEFINE_string("save_path", None, "Directory to write the model and "
"training summaries.")
flags.DEFINE_string("train_data", None, "Training text file. "
"E.g., unzipped file")
"eval_data", None, "File consisting of analogies of four tokens."
"embedding 2 - embedding 1 + embedding 3 should be close "
"to embedding 4."
"See for how to get 'questions-words.txt'.")
flags.DEFINE_integer("embedding_size", 200, "The embedding dimension size.")
"epochs_to_train", 15,
"Number of epochs to train. Each epoch processes the training data once "
flags.DEFINE_float("learning_rate", 0.2, "Initial learning rate.")
flags.DEFINE_integer("num_neg_samples", 100,
"Negative samples per training example.")
flags.DEFINE_integer("batch_size", 16,
"Number of training examples processed per step "
"(size of a minibatch).")
flags.DEFINE_integer("concurrent_steps", 12,
"The number of concurrent training steps.")
flags.DEFINE_integer("window_size", 5,
"The number of words to predict to the left and right "
"of the target word.")
flags.DEFINE_integer("min_count", 5,
"The minimum number of word occurrences for it to be "
"included in the vocabulary.")
flags.DEFINE_float("subsample", 1e-3,
"Subsample threshold for word occurrence. Words that appear "
"with higher frequency will be randomly down-sampled. Set "
"to 0 to disable.")
"interactive", False,
"If true, enters an IPython interactive session to play with the trained "
"model. E.g., try model.analogy(b'france', b'paris', b'russia') and "
"model.nearby([b'proton', b'elephant', b'maxwell'])")
flags.DEFINE_integer("statistics_interval", 5,
"Print statistics every n seconds.")
flags.DEFINE_integer("summary_interval", 5,
"Save training summary to file every n seconds (rounded "
"up to statistics interval).")
flags.DEFINE_integer("checkpoint_interval", 600,
"Checkpoint the model (i.e. save the parameters) every n "
"seconds (rounded up to statistics interval).")
class Options(object):
"""Options used by our word2vec model."""
def __init__(self):
# Model options.
# Embedding dimension.
self.emb_dim = FLAGS.embedding_size
# Training options.
# The training text file.
self.train_data = FLAGS.train_data
# Number of negative samples per example.
self.num_samples = FLAGS.num_neg_samples
# The initial learning rate.
self.learning_rate = FLAGS.learning_rate
# Number of epochs to train. After these many epochs, the learning
# rate decays linearly to zero and the training stops.
self.epochs_to_train = FLAGS.epochs_to_train
# Concurrent training steps.
self.concurrent_steps = FLAGS.concurrent_steps
# Number of examples for one training step.
self.batch_size = FLAGS.batch_size
# The number of words to predict to the left and right of the target word.
self.window_size = FLAGS.window_size
# The minimum number of word occurrences for it to be included in the
# vocabulary.
self.min_count = FLAGS.min_count
# Subsampling threshold for word occurrence.
self.subsample = FLAGS.subsample
# How often to print statistics.
self.statistics_interval = FLAGS.statistics_interval
# How often to write to the summary file (rounds up to the nearest
# statistics_interval).
self.summary_interval = FLAGS.summary_interval
# How often to write checkpoints (rounds up to the nearest statistics
# interval).
self.checkpoint_interval = FLAGS.checkpoint_interval
# Where to write out summaries.
self.save_path = FLAGS.save_path
if not os.path.exists(self.save_path):
# Eval options.
# The text file for eval.
self.eval_data = FLAGS.eval_data
class Word2Vec(object):
"""Word2Vec model (Skipgram)."""
def __init__(self, options, session):
self._options = options
self._session = session
self._word2id = {}
self._id2word = []
def read_analogies(self):
"""Reads through the analogy question file.
questions: a [n, 4] numpy array containing the analogy question's
word ids.
questions_skipped: questions skipped due to unknown words.
questions = []
questions_skipped = 0
with open(self._options.eval_data, "rb") as analogy_f:
for line in analogy_f:
if line.startswith(b":"): # Skip comments.
words = line.strip().lower().split(b" ")
ids = [self._word2id.get(w.strip()) for w in words]
if None in ids or len(ids) != 4:
questions_skipped += 1
print("Eval analogy file: ", self._options.eval_data)
print("Questions: ", len(questions))
print("Skipped: ", questions_skipped)
self._analogy_questions = np.array(questions, dtype=np.int32)
def forward(self, examples, labels):
"""Build the graph for the forward pass."""
opts = self._options
# Declare all variables we need.
# Embedding: [vocab_size, emb_dim]
init_width = 0.5 / opts.emb_dim
emb = tf.Variable(
[opts.vocab_size, opts.emb_dim], -init_width, init_width),
self._emb = emb
# Softmax weight: [vocab_size, emb_dim]. Transposed.
sm_w_t = tf.Variable(
tf.zeros([opts.vocab_size, opts.emb_dim]),
# Softmax bias: [emb_dim].
sm_b = tf.Variable(tf.zeros([opts.vocab_size]), name="sm_b")
# Global step: scalar, i.e., shape [].
self.global_step = tf.Variable(0, name="global_step")
# Nodes to compute the nce loss w/ candidate sampling.
labels_matrix = tf.reshape(
[opts.batch_size, 1])
# Negative sampling.
sampled_ids, _, _ = (tf.nn.fixed_unigram_candidate_sampler(
# Embeddings for examples: [batch_size, emb_dim]
example_emb = tf.nn.embedding_lookup(emb, examples)
# Weights for labels: [batch_size, emb_dim]
true_w = tf.nn.embedding_lookup(sm_w_t, labels)
# Biases for labels: [batch_size, 1]
true_b = tf.nn.embedding_lookup(sm_b, labels)
# Weights for sampled ids: [num_sampled, emb_dim]
sampled_w = tf.nn.embedding_lookup(sm_w_t, sampled_ids)
# Biases for sampled ids: [num_sampled, 1]
sampled_b = tf.nn.embedding_lookup(sm_b, sampled_ids)
# True logits: [batch_size, 1]
true_logits = tf.reduce_sum(tf.mul(example_emb, true_w), 1) + true_b
# Sampled logits: [batch_size, num_sampled]
# We replicate sampled noise labels for all examples in the batch
# using the matmul.
sampled_b_vec = tf.reshape(sampled_b, [opts.num_samples])
sampled_logits = tf.matmul(example_emb,
transpose_b=True) + sampled_b_vec
return true_logits, sampled_logits
def nce_loss(self, true_logits, sampled_logits):
"""Build the graph for the NCE loss."""
# cross-entropy(logits, labels)
opts = self._options
true_xent = tf.nn.sigmoid_cross_entropy_with_logits(
labels=tf.ones_like(true_logits), logits=true_logits)
sampled_xent = tf.nn.sigmoid_cross_entropy_with_logits(
labels=tf.zeros_like(sampled_logits), logits=sampled_logits)
# NCE-loss is the sum of the true and noise (sampled words)
# contributions, averaged over the batch.
nce_loss_tensor = (tf.reduce_sum(true_xent) +
tf.reduce_sum(sampled_xent)) / opts.batch_size
return nce_loss_tensor
def optimize(self, loss):
"""Build the graph to optimize the loss function."""
# Optimizer nodes.
# Linear learning rate decay.
opts = self._options
words_to_train = float(opts.words_per_epoch * opts.epochs_to_train)
lr = opts.learning_rate * tf.maximum(
0.0001, 1.0 - tf.cast(self._words, tf.float32) / words_to_train)
self._lr = lr
optimizer = tf.train.GradientDescentOptimizer(lr)
train = optimizer.minimize(loss,
self._train = train
def build_eval_graph(self):
"""Build the eval graph."""
# Eval graph
# Each analogy task is to predict the 4th word (d) given three
# words: a, b, c. E.g., a=italy, b=rome, c=france, we should
# predict d=paris.
# The eval feeds three vectors of word ids for a, b, c, each of
# which is of size N, where N is the number of analogies we want to
# evaluate in one batch.
analogy_a = tf.placeholder(dtype=tf.int32) # [N]
analogy_b = tf.placeholder(dtype=tf.int32) # [N]
analogy_c = tf.placeholder(dtype=tf.int32) # [N]
# Normalized word embeddings of shape [vocab_size, emb_dim].
nemb = tf.nn.l2_normalize(self._emb, 1)
# Each row of a_emb, b_emb, c_emb is a word's embedding vector.
# They all have the shape [N, emb_dim]
a_emb = tf.gather(nemb, analogy_a) # a's embs
b_emb = tf.gather(nemb, analogy_b) # b's embs
c_emb = tf.gather(nemb, analogy_c) # c's embs
# We expect that d's embedding vectors on the unit hyper-sphere is
# near: c_emb + (b_emb - a_emb), which has the shape [N, emb_dim].
target = c_emb + (b_emb - a_emb)
# Compute cosine distance between each pair of target and vocab.
# dist has shape [N, vocab_size].
dist = tf.matmul(target, nemb, transpose_b=True)
# For each question (row in dist), find the top 4 words.
_, pred_idx = tf.nn.top_k(dist, 4)
# Nodes for computing neighbors for a given word according to
# their cosine distance.
nearby_word = tf.placeholder(dtype=tf.int32) # word id
nearby_emb = tf.gather(nemb, nearby_word)
nearby_dist = tf.matmul(nearby_emb, nemb, transpose_b=True)
nearby_val, nearby_idx = tf.nn.top_k(nearby_dist,
min(1000, self._options.vocab_size))
# Nodes in the construct graph which are used by training and
# evaluation to run/feed/fetch.
self._analogy_a = analogy_a
self._analogy_b = analogy_b
self._analogy_c = analogy_c
self._analogy_pred_idx = pred_idx
self._nearby_word = nearby_word
self._nearby_val = nearby_val
self._nearby_idx = nearby_idx
def build_graph(self):
"""Build the graph for the full model."""
opts = self._options
# The training data. A text file.
(words, counts, words_per_epoch, self._epoch, self._words, examples,
labels) = word2vec.skipgram_word2vec(filename=opts.train_data,
(opts.vocab_words, opts.vocab_counts,
opts.words_per_epoch) =[words, counts, words_per_epoch])
opts.vocab_size = len(opts.vocab_words)
print("Data file: ", opts.train_data)
print("Vocab size: ", opts.vocab_size - 1, " + UNK")
print("Words per epoch: ", opts.words_per_epoch)
self._examples = examples
self._labels = labels
self._id2word = opts.vocab_words
for i, w in enumerate(self._id2word):
self._word2id[w] = i
true_logits, sampled_logits = self.forward(examples, labels)
loss = self.nce_loss(true_logits, sampled_logits)
tf.scalar_summary("NCE loss", loss)
self._loss = loss
# Properly initialize all variables.
self.saver = tf.train.Saver()
def save_vocab(self):
"""Save the vocabulary to a file so the model can be reloaded."""
opts = self._options
with open(os.path.join(opts.save_path, "vocab.txt"), "w") as f:
for i in xrange(opts.vocab_size):
vocab_word = tf.compat.as_text(opts.vocab_words[i]).encode("utf-8")
f.write("%s %d\n" % (vocab_word,
def _train_thread_body(self):
initial_epoch, =[self._epoch])
while True:
_, epoch =[self._train, self._epoch])
if epoch != initial_epoch:
def train(self):
"""Train the model."""
opts = self._options
initial_epoch, initial_words =[self._epoch, self._words])
summary_op = tf.summary.merge_all()
summary_writer = tf.summary.FileWriter(opts.save_path, self._session.graph)
workers = []
for _ in xrange(opts.concurrent_steps):
t = threading.Thread(target=self._train_thread_body)
last_words, last_time, last_summary_time = initial_words, time.time(), 0
last_checkpoint_time = 0
while True:
time.sleep(opts.statistics_interval) # Reports our progress once a while.
(epoch, step, loss, words, lr) =
[self._epoch, self.global_step, self._loss, self._words, self._lr])
now = time.time()
last_words, last_time, rate = words, now, (words - last_words) / (
now - last_time)
print("Epoch %4d Step %8d: lr = %5.3f loss = %6.2f words/sec = %8.0f\r" %
(epoch, step, lr, loss, rate), end="")
if now - last_summary_time > opts.summary_interval:
summary_str =
summary_writer.add_summary(summary_str, step)
last_summary_time = now
if now - last_checkpoint_time > opts.checkpoint_interval:,
os.path.join(opts.save_path, "model.ckpt"),
last_checkpoint_time = now
if epoch != initial_epoch:
for t in workers:
return epoch
def _predict(self, analogy):
"""Predict the top 4 answers for analogy questions."""
idx, =[self._analogy_pred_idx], {
self._analogy_a: analogy[:, 0],
self._analogy_b: analogy[:, 1],
self._analogy_c: analogy[:, 2]
return idx
def eval(self):
"""Evaluate analogy questions and reports accuracy."""
# How many questions we get right at precision@1.
correct = 0
total = self._analogy_questions.shape[0]
except AttributeError as e:
raise AttributeError("Need to read analogy questions.")
start = 0
while start < total:
limit = start + 2500
sub = self._analogy_questions[start:limit, :]
idx = self._predict(sub)
start = limit
for question in xrange(sub.shape[0]):
for j in xrange(4):
if idx[question, j] == sub[question, 3]:
# Bingo! We predicted correctly. E.g., [italy, rome, france, paris].
correct += 1
elif idx[question, j] in sub[question, :3]:
# We need to skip words already in the question.
# The correct label is not the precision@1
print("Eval %4d/%d accuracy = %4.1f%%" % (correct, total,
correct * 100.0 / total))
def analogy(self, w0, w1, w2):
"""Predict word w3 as in w0:w1 vs w2:w3."""
wid = np.array([[self._word2id.get(w, 0) for w in [w0, w1, w2]]])
idx = self._predict(wid)
for c in [self._id2word[i] for i in idx[0, :]]:
if c not in [w0, w1, w2]:
def nearby(self, words, num=20):
"""Prints out nearby words given a list of words."""
ids = np.array([self._word2id.get(x, 0) for x in words])
vals, idx =
[self._nearby_val, self._nearby_idx], {self._nearby_word: ids})
for i in xrange(len(words)):
print("\n%s\n=====================================" % (words[i]))
for (neighbor, distance) in zip(idx[i, :num], vals[i, :num]):
print("%-20s %6.4f" % (self._id2word[neighbor], distance))
def _start_shell(local_ns=None):
# An interactive shell is useful for debugging/development.
import IPython
user_ns = {}
if local_ns:
IPython.start_ipython(argv=[], user_ns=user_ns)
def main(_):
"""Train a word2vec model."""
if not FLAGS.train_data or not FLAGS.eval_data or not FLAGS.save_path:
print("--train_data --eval_data and --save_path must be specified.")
opts = Options()
with tf.Graph().as_default(), tf.Session() as session:
with tf.device("/cpu:0"):
model = Word2Vec(opts, session)
model.read_analogies() # Read analogy questions
for _ in xrange(opts.epochs_to_train):
model.train() # Process one epoch
model.eval() # Eval analogies.
# Perform a final save.,
os.path.join(opts.save_path, "model.ckpt"),
if FLAGS.interactive:
# E.g.,
# [0]: model.analogy(b'france', b'paris', b'russia')
# [1]: model.nearby([b'proton', b'elephant', b'maxwell'])
if __name__ == "__main__":