"""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.
http://arxiv.org/abs/1301.3781
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.
"""
word2vec = tf.load_op_library(os.path.join(os.path.dirname(os.path.realpath(__file__)), "word2vec_ops.so"))
flags = tf.app.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 http://mattmahoney.net/dc/text8.zip.")
flags.DEFINE_string("eval_data", None, "File consisting of analogies of four tokens." "embedding 2 - embedding 1 + embedding 3 should be close " "to embedding 4." "See README.md for how to get 'questions-words.txt'.")
flags.DEFINE_integer("embedding_size", 200, "The embedding dimension size.")
flags.DEFINE_integer("epochs_to_train", 15, "Number of epochs to train. Each epoch processes the training data once " "completely.")
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.")
flags.DEFINE_boolean("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).")
FLAGS = flags.FLAGS
class Options(object):
	"""Options used by our word2vec model."""
	def __init__(self):
		self.emb_dim = FLAGS.embedding_size
		self.train_data = FLAGS.train_data
		self.num_samples = FLAGS.num_neg_samples
		self.learning_rate = FLAGS.learning_rate
		self.epochs_to_train = FLAGS.epochs_to_train
		self.concurrent_steps = FLAGS.concurrent_steps
		self.batch_size = FLAGS.batch_size
		self.window_size = FLAGS.window_size
		self.min_count = FLAGS.min_count
		self.subsample = FLAGS.subsample
		self.statistics_interval = FLAGS.statistics_interval
		self.summary_interval = FLAGS.summary_interval
		self.checkpoint_interval = FLAGS.checkpoint_interval
		self.save_path = FLAGS.save_path
		if not os.path.exists(self.save_path):
			os.makedirs(self.save_path)
		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 = []
		self.build_graph()
		self.build_eval_graph()
		self.save_vocab()
	def read_analogies(self):
		"""Reads through the analogy question file.
    Returns:
      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":"):
					continue
				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
				else:
					questions.append(np.array(ids))
		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
		init_width = 0.5 / opts.emb_dim
		emb = tf.Variable(tf.random_uniform([opts.vocab_size, opts.emb_dim], -init_width, init_width), name="emb")
		self._emb = emb
		sm_w_t = tf.Variable(tf.zeros([opts.vocab_size, opts.emb_dim]), name="sm_w_t")
		sm_b = tf.Variable(tf.zeros([opts.vocab_size]), name="sm_b")
		self.global_step = tf.Variable(0, name="global_step")
		labels_matrix = tf.reshape(tf.cast(labels, dtype=tf.int64), [opts.batch_size, 1])
		sampled_ids, _, _ = tf.nn.fixed_unigram_candidate_sampler(true_classes=labels_matrix, num_true=1, num_sampled=opts.num_samples, unique=True, range_max=opts.vocab_size, distortion=0.75, unigrams=opts.vocab_counts.tolist())
		example_emb = tf.nn.embedding_lookup(emb, examples)
		true_w = tf.nn.embedding_lookup(sm_w_t, labels)
		true_b = tf.nn.embedding_lookup(sm_b, labels)
		sampled_w = tf.nn.embedding_lookup(sm_w_t, sampled_ids)
		sampled_b = tf.nn.embedding_lookup(sm_b, sampled_ids)
		true_logits = tf.reduce_sum(tf.multiply(example_emb, true_w), 1) + true_b
		sampled_b_vec = tf.reshape(sampled_b, [opts.num_samples])
		sampled_logits = tf.matmul(example_emb, sampled_w, 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."""
		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_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."""
		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, global_step=self.global_step, gate_gradients=optimizer.GATE_NONE)
		self._train = train
	def build_eval_graph(self):
		"""Build the eval graph."""
		analogy_a = tf.placeholder(dtype=tf.int32)
		analogy_b = tf.placeholder(dtype=tf.int32)
		analogy_c = tf.placeholder(dtype=tf.int32)
		nemb = tf.nn.l2_normalize(self._emb, 1)
		a_emb = tf.gather(nemb, analogy_a)
		b_emb = tf.gather(nemb, analogy_b)
		c_emb = tf.gather(nemb, analogy_c)
		target = c_emb + (b_emb - a_emb)
		dist = tf.matmul(target, nemb, transpose_b=True)
		_, pred_idx = tf.nn.top_k(dist, 4)
		nearby_word = tf.placeholder(dtype=tf.int32)
		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))
		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
		(words, counts, words_per_epoch, self._epoch, self._words, examples, labels) = word2vec.skipgram_word2vec(filename=opts.train_data, batch_size=opts.batch_size, window_size=opts.window_size, min_count=opts.min_count, subsample=opts.subsample)
		(opts.vocab_words, opts.vocab_counts, opts.words_per_epoch) = self._session.run([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.summary.scalar("NCE loss", loss)
		self._loss = loss
		self.optimize(loss)
		tf.global_variables_initializer().run()
		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, opts.vocab_counts[i]))
	def _train_thread_body(self):
		initial_epoch, = self._session.run([self._epoch])
		while True:
			_, epoch = self._session.run([self._train, self._epoch])
			if epoch != initial_epoch:
				break
	def train(self):
		"""Train the model."""
		opts = self._options
		initial_epoch, initial_words = self._session.run([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)
			t.start()
			workers.append(t)
		last_words, last_time, last_summary_time = initial_words, time.time(), 0
		last_checkpoint_time = 0
		while True:
			time.sleep(opts.statistics_interval)
			(epoch, step, loss, words, lr) = self._session.run([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="")
			sys.stdout.flush()
			if now - last_summary_time > opts.summary_interval:
				summary_str = self._session.run(summary_op)
				summary_writer.add_summary(summary_str, step)
				last_summary_time = now
			if now - last_checkpoint_time > opts.checkpoint_interval:
				self.saver.save(self._session, os.path.join(opts.save_path, "model.ckpt"), global_step=step.astype(int))
				last_checkpoint_time = now
			if epoch != initial_epoch:
				break
		for t in workers:
			t.join()
		return epoch
	def _predict(self, analogy):
		"""Predict the top 4 answers for analogy questions."""
		idx, = self._session.run([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."""
		correct = 0
		try:
			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]:
						correct += 1
						break
					elif idx[question, j] in sub[question, :3]:
						continue
					else:
						break
		print()
		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]:
				print(c)
				return
		print("unknown")
	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._session.run([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):
	user_ns = {}
	if local_ns:
		user_ns.update(local_ns)
	user_ns.update(globals())
	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.")
		sys.exit(1)
	opts = Options()
	with tf.Graph().as_default(), tf.Session() as session:
		with tf.device("/cpu:0"):
			model = Word2Vec(opts, session)
			model.read_analogies()
		for _ in xrange(opts.epochs_to_train):
			model.train()
			model.eval()
		model.saver.save(session, os.path.join(opts.save_path, "model.ckpt"), global_step=model.global_step)
		if FLAGS.interactive:
			_start_shell(locals())
if __name__ == "__main__":
	tf.app.run()