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vae.py
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###
'''
Replication of M1 from http://arxiv.org/abs/1406.5298
Title: Semi-Supervised Learning with Deep Generative Models
Authors: Diederik P. Kingma, Danilo J. Rezende, Shakir Mohamed, Max Welling
Original Implementation (Theano): https://github.com/dpkingma/nips14-ssl
---
Code By: S. Saemundsson
'''
###
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import prettytensor as pt
import tensorflow as tf
import utils
import numpy as np
import time
from neuralnetworks import FullyConnected
from prettytensor import bookkeeper
class VariationalAutoencoder(object):
def __init__( self,
dim_x, dim_z,
p_x = 'bernoulli',
q_z = 'gaussian_marg',
p_z = 'gaussian_marg',
hidden_layers_px = [600, 600],
hidden_layers_qz = [600, 600],
nonlin_px = tf.nn.softplus,
nonlin_qz = tf.nn.softplus,
l2_loss = 0.0 ):
self.dim_x, self.dim_z = dim_x, dim_z
self.l2_loss = l2_loss
self.distributions = { 'p_x': p_x,
'q_z': q_z,
'p_z': p_z }
''' Create Graph '''
self.G = tf.Graph()
with self.G.as_default():
self.x = tf.placeholder( tf.float32, [None, self.dim_x] )
self.encoder = FullyConnected( dim_output = 2 * self.dim_z,
hidden_layers = hidden_layers_qz,
nonlinearity = nonlin_qz )
self.decoder = FullyConnected( dim_output = self.dim_x,
hidden_layers = hidden_layers_px,
nonlinearity = nonlin_px )
self._objective()
self.saver = tf.train.Saver()
self.session = tf.Session()
def _draw_sample( self, mu, log_sigma_sq ):
epsilon = tf.random_normal( ( tf.shape( mu ) ), 0, 1 )
sample = tf.add( mu,
tf.mul(
tf.exp( 0.5 * log_sigma_sq ), epsilon ) )
return sample
def _generate_zx( self, x, phase = pt.Phase.train, reuse = False ):
with tf.variable_scope('encoder', reuse = reuse):
encoder_out = self.encoder.output( x, phase = phase )
z_mu, z_lsgms = encoder_out.split( split_dim = 1, num_splits = 2 )
z_sample = self._draw_sample( z_mu, z_lsgms )
return z_sample, z_mu, z_lsgms
def _generate_xz( self, z, phase = pt.Phase.train, reuse = False ):
with tf.variable_scope('decoder', reuse = reuse):
x_recon_logits = self.decoder.output( z, phase = phase )
x_recon = tf.nn.sigmoid( x_recon_logits )
return x_recon, x_recon_logits
def _objective( self ):
############
''' Cost '''
############
self.z_sample, self.z_mu, self.z_lsgms = self._generate_zx( self.x )
self.x_recon, self.x_recon_logits = self._generate_xz( self.z_sample )
if self.distributions['p_z'] == 'gaussian_marg':
prior_z = tf.reduce_sum( utils.tf_gaussian_marg( self.z_mu, self.z_lsgms ), 1 )
if self.distributions['q_z'] == 'gaussian_marg':
post_z = tf.reduce_sum( utils.tf_gaussian_ent( self.z_lsgms ), 1 )
if self.distributions['p_x'] == 'bernoulli':
self.log_lik = - tf.reduce_sum( utils.tf_binary_xentropy( self.x, self.x_recon ), 1 )
l2 = tf.add_n([tf.nn.l2_loss(v) for v in tf.trainable_variables()])
self.cost = tf.reduce_mean( post_z - prior_z - self.log_lik ) + self.l2_loss * l2
##################
''' Evaluation '''
##################
self.z_sample_eval, _, _ = self._generate_zx( self.x, phase = pt.Phase.test, reuse = True )
self.x_recon_eval, _ = self._generate_xz( self.z_sample_eval, phase = pt.Phase.test, reuse = True )
self.eval_log_lik = - tf.reduce_mean( tf.reduce_sum( utils.tf_binary_xentropy( self.x, self.x_recon_eval ), 1 ) )
def train( self, x, x_valid,
epochs, num_batches,
print_every = 1,
learning_rate = 3e-4,
beta1 = 0.9,
beta2 = 0.999,
seed = 31415,
stop_iter = 100,
save_path = None,
load_path = None,
draw_img = 1 ):
self.num_examples = x.shape[0]
self.num_batches = num_batches
assert self.num_examples % self.num_batches == 0, '#Examples % #Batches != 0'
self.batch_size = self.num_examples // self.num_batches
''' Session and Summary '''
if save_path is None:
self.save_path = 'checkpoints/model_VAE_{}-{}_{}.cpkt'.format(learning_rate,self.batch_size,time.time())
else:
self.save_path = save_path
np.random.seed(seed)
tf.set_random_seed(seed)
with self.G.as_default():
self.optimiser = tf.train.AdamOptimizer( learning_rate = learning_rate, beta1 = beta1, beta2 = beta2 )
self.train_op = self.optimiser.minimize( self.cost )
init = tf.initialize_all_variables()
self._test_vars = None
with self.session as sess:
sess.run(init)
if load_path == 'default': self.saver.restore( sess, self.save_path )
elif load_path is not None: self.saver.restore( sess, load_path )
training_cost = 0.
best_eval_log_lik = - np.inf
stop_counter = 0
for epoch in range(epochs):
''' Shuffle Data '''
np.random.shuffle( x )
''' Training '''
for x_batch in utils.feed_numpy( self.batch_size, x ):
training_result = sess.run( [self.train_op, self.cost],
feed_dict = { self.x: x_batch } )
training_cost = training_result[1]
''' Evaluation '''
stop_counter += 1
if epoch % print_every == 0:
test_vars = tf.get_collection(bookkeeper.GraphKeys.TEST_VARIABLES)
if test_vars:
if test_vars != self._test_vars:
self._test_vars = list(test_vars)
self._test_var_init_op = tf.initialize_variables(test_vars)
self._test_var_init_op.run()
eval_log_lik, x_recon_eval = \
sess.run( [self.eval_log_lik, self.x_recon_eval],
feed_dict = { self.x: x_valid } )
if eval_log_lik > best_eval_log_lik:
best_eval_log_lik = eval_log_lik
self.saver.save( sess, self.save_path )
stop_counter = 0
utils.print_metrics( epoch+1,
['Training', 'cost', training_cost],
['Validation', 'log-likelihood', eval_log_lik] )
if draw_img > 0 and epoch % draw_img == 0:
import matplotlib
matplotlib.use('Agg')
import pylab
import seaborn as sns
five_random = np.random.random_integers(x_valid.shape[0], size = 5)
x_sample = x_valid[five_random]
x_recon_sample = x_recon_eval[five_random]
sns.set_style('white')
f, axes = pylab.subplots(5, 2, figsize=(8,12))
for i,row in enumerate(axes):
row[0].imshow(x_sample[i].reshape(28, 28), vmin=0, vmax=1)
im = row[1].imshow(x_recon_sample[i].reshape(28, 28), vmin=0, vmax=1,
cmap=sns.light_palette((1.0, 0.4980, 0.0549), input="rgb", as_cmap=True))
pylab.setp([a.get_xticklabels() for a in row], visible=False)
pylab.setp([a.get_yticklabels() for a in row], visible=False)
f.subplots_adjust(left=0.0, right=0.9, bottom=0.0, top=1.0)
cbar_ax = f.add_axes([0.9, 0.1, 0.04, 0.8])
f.colorbar(im, cax=cbar_ax, use_gridspec=True)
pylab.tight_layout()
pylab.savefig('img/recon-'+str(epoch)+'.png', format='png')
pylab.clf()
pylab.close('all')
if stop_counter >= stop_iter:
print('Stopping VAE training')
print('No change in validation log-likelihood for {} iterations'.format(stop_iter))
print('Best validation log-likelihood: {}'.format(best_eval_log_lik))
print('Model saved in {}'.format(self.save_path))
break
def encode( self, x, sample = False ):
if sample:
return self.session.run( [self.z_sample, self.z_mu, self.z_lsgms], feed_dict = { self.x: x } )
else:
return self.session.run( [self.z_mu, self.z_lsgms], feed_dict = { self.x: x } )
def decode( self, z ):
return self.session.run( [self.x_recon],
feed_dict = { self.z_sample: z } )