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model.py
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model.py
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import tensorflow as tf
from tensorflow.contrib import rnn
from tensorflow.contrib import legacy_seq2seq
import random
import numpy as np
from beam import BeamSearch
class Model():
def __init__(self, args, infer=False):
self.args = args
if infer:
args.batch_size = 1
args.seq_length = 1
if args.model == 'rnn':
cell_fn = rnn.BasicRNNCell
elif args.model == 'gru':
cell_fn = rnn.GRUCell
elif args.model == 'lstm':
cell_fn = rnn.BasicLSTMCell
else:
raise Exception("model type not supported: {}".format(args.model))
cells = []
for _ in range(args.num_layers):
cell = cell_fn(args.rnn_size)
cells.append(cell)
self.cell = cell = rnn.MultiRNNCell(cells)
self.input_data = tf.placeholder(tf.int32, [args.batch_size, args.seq_length])
self.targets = tf.placeholder(tf.int32, [args.batch_size, args.seq_length])
self.initial_state = cell.zero_state(args.batch_size, tf.float32)
self.batch_pointer = tf.Variable(0, name="batch_pointer", trainable=False, dtype=tf.int32)
self.inc_batch_pointer_op = tf.assign(self.batch_pointer, self.batch_pointer + 1)
self.epoch_pointer = tf.Variable(0, name="epoch_pointer", trainable=False)
self.batch_time = tf.Variable(0.0, name="batch_time", trainable=False)
tf.summary.scalar("time_batch", self.batch_time)
def variable_summaries(var):
"""Attach a lot of summaries to a Tensor (for TensorBoard visualization)."""
with tf.name_scope('summaries'):
mean = tf.reduce_mean(var)
tf.summary.scalar('mean', mean)
#with tf.name_scope('stddev'):
# stddev = tf.sqrt(tf.reduce_mean(tf.square(var - mean)))
#tf.summary.scalar('stddev', stddev)
tf.summary.scalar('max', tf.reduce_max(var))
tf.summary.scalar('min', tf.reduce_min(var))
#tf.summary.histogram('histogram', var)
with tf.variable_scope('rnnlm'):
softmax_w = tf.get_variable("softmax_w", [args.rnn_size, args.vocab_size])
variable_summaries(softmax_w)
softmax_b = tf.get_variable("softmax_b", [args.vocab_size])
variable_summaries(softmax_b)
with tf.device("/cpu:0"):
embedding = tf.get_variable("embedding", [args.vocab_size, args.rnn_size])
inputs = tf.split(tf.nn.embedding_lookup(embedding, self.input_data), args.seq_length, 1)
inputs = [tf.squeeze(input_, [1]) for input_ in inputs]
def loop(prev, _):
prev = tf.matmul(prev, softmax_w) + softmax_b
prev_symbol = tf.stop_gradient(tf.argmax(prev, 1))
return tf.nn.embedding_lookup(embedding, prev_symbol)
outputs, last_state = legacy_seq2seq.rnn_decoder(inputs, self.initial_state, cell, loop_function=loop if infer else None, scope='rnnlm')
output = tf.reshape(tf.concat(outputs, 1), [-1, args.rnn_size])
self.logits = tf.matmul(output, softmax_w) + softmax_b
self.probs = tf.nn.softmax(self.logits)
loss = legacy_seq2seq.sequence_loss_by_example([self.logits],
[tf.reshape(self.targets, [-1])],
[tf.ones([args.batch_size * args.seq_length])],
args.vocab_size)
self.cost = tf.reduce_sum(loss) / args.batch_size / args.seq_length
tf.summary.scalar("cost", self.cost)
self.final_state = last_state
self.lr = tf.Variable(0.0, trainable=False)
tvars = tf.trainable_variables()
grads, _ = tf.clip_by_global_norm(tf.gradients(self.cost, tvars),
args.grad_clip)
optimizer = tf.train.AdamOptimizer(self.lr)
self.train_op = optimizer.apply_gradients(zip(grads, tvars))
def sample(self, sess, words, vocab, num=200, prime='first all', sampling_type=1, pick=0, width=4, quiet=False):
def weighted_pick(weights):
t = np.cumsum(weights)
s = np.sum(weights)
return(int(np.searchsorted(t, np.random.rand(1)*s)))
def beam_search_predict(sample, state):
"""Returns the updated probability distribution (`probs`) and
`state` for a given `sample`. `sample` should be a sequence of
vocabulary labels, with the last word to be tested against the RNN.
"""
x = np.zeros((1, 1))
x[0, 0] = sample[-1]
feed = {self.input_data: x, self.initial_state: state}
[probs, final_state] = sess.run([self.probs, self.final_state],
feed)
return probs, final_state
def beam_search_pick(prime, width):
"""Returns the beam search pick."""
if not len(prime) or prime == ' ':
prime = random.choice(list(vocab.keys()))
prime_labels = [vocab.get(word, 0) for word in prime.split()]
bs = BeamSearch(beam_search_predict,
sess.run(self.cell.zero_state(1, tf.float32)),
prime_labels)
samples, scores = bs.search(None, None, k=width, maxsample=num)
return samples[np.argmin(scores)]
ret = ''
if pick == 1:
state = sess.run(self.cell.zero_state(1, tf.float32))
if not len(prime) or prime == ' ':
prime = random.choice(list(vocab.keys()))
if not quiet:
print(prime)
for word in prime.split()[:-1]:
if not quiet:
print(word)
x = np.zeros((1, 1))
x[0, 0] = vocab.get(word,0)
feed = {self.input_data: x, self.initial_state:state}
[state] = sess.run([self.final_state], feed)
ret = prime
word = prime.split()[-1]
for n in range(num):
x = np.zeros((1, 1))
x[0, 0] = vocab.get(word, 0)
feed = {self.input_data: x, self.initial_state:state}
[probs, state] = sess.run([self.probs, self.final_state], feed)
p = probs[0]
if sampling_type == 0:
sample = np.argmax(p)
elif sampling_type == 2:
if word == '\n':
sample = weighted_pick(p)
else:
sample = np.argmax(p)
else: # sampling_type == 1 default:
sample = weighted_pick(p)
pred = words[sample]
ret += ' ' + pred
word = pred
elif pick == 2:
pred = beam_search_pick(prime, width)
for i, label in enumerate(pred):
ret += ' ' + words[label] if i > 0 else words[label]
return ret