f5712d0 Dec 28, 2016
440 lines (366 sloc) 15.3 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 unbatched skip-gram model.
Trains the model described in:
(Mikolov, et. al.) Efficient Estimation of Word Representations in Vector Space
ICLR 2013.
This model does true SGD (i.e. no minibatching). To do this efficiently, custom
ops are used to sequentially process data within a 'batch'.
The key ops used are:
* skipgram custom op that does input processing.
* neg_train custom op that efficiently calculates and applies the gradient using
true SGD.
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.")
"train_data", None,
"Training data. E.g., unzipped file")
"eval_data", None, "Analogy questions. "
"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", 0.025, "Initial learning rate.")
flags.DEFINE_integer("num_neg_samples", 25,
"Negative samples per training example.")
flags.DEFINE_integer("batch_size", 500,
"Numbers of training examples each step processes "
"(no minibatching).")
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'])")
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
# 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 build_graph(self):
"""Build the model graph."""
opts = self._options
# The training data. A text file.
(words, counts, words_per_epoch, current_epoch, total_words_processed,
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._id2word = opts.vocab_words
for i, w in enumerate(self._id2word):
self._word2id[w] = i
# Declare all variables we need.
# Input words embedding: [vocab_size, emb_dim]
w_in = tf.Variable(
opts.emb_dim], -0.5 / opts.emb_dim, 0.5 / opts.emb_dim),
# Global step: scalar, i.e., shape [].
w_out = tf.Variable(tf.zeros([opts.vocab_size, opts.emb_dim]), name="w_out")
# Global step: []
global_step = tf.Variable(0, name="global_step")
# Linear learning rate decay.
words_to_train = float(opts.words_per_epoch * opts.epochs_to_train)
lr = opts.learning_rate * tf.maximum(
1.0 - tf.cast(total_words_processed, tf.float32) / words_to_train)
# Training nodes.
inc = global_step.assign_add(1)
with tf.control_dependencies([inc]):
train = word2vec.neg_train_word2vec(w_in,
self._w_in = w_in
self._examples = examples
self._labels = labels
self._lr = lr
self._train = train
self.global_step = global_step
self._epoch = current_epoch
self._words = total_words_processed
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 build_eval_graph(self):
"""Build the evaluation graph."""
# Eval graph
opts = self._options
# 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._w_in, 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, opts.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
# Properly initialize all variables.
self.saver = tf.train.Saver()
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])
workers = []
for _ in xrange(opts.concurrent_steps):
t = threading.Thread(target=self._train_thread_body)
last_words, last_time = initial_words, time.time()
while True:
time.sleep(5) # Reports our progress once a while.
(epoch, step, words, lr) =
[self._epoch, self.global_step, 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 words/sec = %8.0f\r" % (epoch, step,
lr, rate),
if epoch != initial_epoch:
for t in workers:
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__":