-
Notifications
You must be signed in to change notification settings - Fork 3
/
univariate_gauss_adam.py
144 lines (114 loc) · 4.62 KB
/
univariate_gauss_adam.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
# Copyright (c) 2017, Kyle Lo
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.
import numpy as np
import tensorflow as tf
from util.sprint import sfill, sfloat, shess
from util.plot import plot_canonical_gauss
TRUE_MU = 10.0
TRUE_SIGMA = 5.0
SAMPLE_SIZE = 100
INIT_MU_PARAMS = {'loc': 0.0, 'scale': 0.1}
INIT_PHI_PARAMS = {'loc': 1.0, 'scale': 0.1}
LEARNING_RATE = 0.001
MAX_ITER = 10000
TOL_PARAM, TOL_LOSS, TOL_GRAD = 1e-8, 1e-8, 1e-8
RANDOM_SEED = 0
MAX_CHARS = 15
# generate sample
np.random.seed(0)
x_obs = np.random.normal(loc=TRUE_MU, scale=TRUE_SIGMA, size=SAMPLE_SIZE)
# center and scale the data
CENTER = x_obs.min()
SCALE = x_obs.max() - x_obs.min()
x_obs = (x_obs - CENTER) / SCALE
# tensor for data
x = tf.placeholder(dtype=tf.float32)
# tensors for parameters
np.random.seed(RANDOM_SEED)
mu = tf.Variable(initial_value=np.random.normal(**INIT_MU_PARAMS),
dtype=tf.float32)
phi = tf.Variable(initial_value=np.random.normal(**INIT_PHI_PARAMS),
dtype=tf.float32)
sigma = tf.square(phi)
# loss function
gaussian_dist = tf.contrib.distributions.Normal(loc=mu, scale=sigma)
log_prob = gaussian_dist.log_prob(value=x)
neg_log_likelihood = -1.0 * tf.reduce_sum(log_prob)
# optimizer
optimizer = tf.train.AdamOptimizer(learning_rate=LEARNING_RATE)
train_op = optimizer.minimize(loss=neg_log_likelihood)
# gradient
grad = tf.gradients(neg_log_likelihood, [mu, phi])
# hessian
hess = tf.stack(values=[tf.gradients(grad[0], [mu, phi]),
tf.gradients(grad[1], [mu, phi])], axis=0)
with tf.Session() as sess:
# initialize
sess.run(fetches=tf.global_variables_initializer())
i = 1
obs_mu, obs_phi, obs_sigma = sess.run(fetches=[[mu], [phi], [sigma]])
obs_loss = sess.run(fetches=[neg_log_likelihood], feed_dict={x: x_obs})
obs_grad = sess.run(fetches=[grad], feed_dict={x: x_obs})
obs_hess = sess.run(fetches=[hess], feed_dict={x: x_obs})
print(' {} | {} | {} | {} | {}'
.format(sfill('iter', len(str(MAX_ITER)), '>'),
sfill('mu', MAX_CHARS, '^'),
sfill('sigma', MAX_CHARS, '^'),
sfill('loss', MAX_CHARS, '^'),
sfill('grad', MAX_CHARS, '^')))
while True:
# gradient step
sess.run(fetches=train_op, feed_dict={x: x_obs})
# update parameters
new_mu, new_phi, new_sigma = sess.run(fetches=[mu, phi, sigma])
diff_norm = np.linalg.norm(np.subtract([new_mu, new_phi],
[obs_mu[-1], obs_phi[-1]]))
# update loss
new_loss = sess.run(fetches=neg_log_likelihood, feed_dict={x: x_obs})
loss_diff = np.abs(new_loss - obs_loss[-1])
# update gradient
new_grad = sess.run(fetches=grad, feed_dict={x: x_obs})
grad_norm = np.linalg.norm(new_grad)
# update hessian
new_hess = sess.run(fetches=hess, feed_dict={x: x_obs})
obs_mu.append(new_mu)
obs_phi.append(new_phi)
obs_sigma.append(new_sigma)
obs_loss.append(new_loss)
obs_grad.append(new_grad)
obs_hess.append(new_hess)
if (i - 1) % 100 == 0:
print(' {} | {} | {} | {} | {}'
.format(sfill(i, len(str(MAX_ITER))),
sfloat(new_mu, MAX_CHARS),
sfloat(new_sigma, MAX_CHARS),
sfloat(new_loss, MAX_CHARS),
sfloat(grad_norm, MAX_CHARS)))
if diff_norm < TOL_PARAM:
print('Parameter convergence in {} iterations!'.format(i))
break
if loss_diff < TOL_LOSS:
print('Loss function convergence in {} iterations!'.format(i))
break
if grad_norm < TOL_GRAD:
print('Gradient convergence in {} iterations!'.format(i))
break
if i >= MAX_ITER:
print('Max number of iterations reached without convergence.')
break
i += 1
# print results
print('Fitted MLE: [{:.4f}, {:.4f}]'.format(obs_mu[-1], obs_sigma[-1]))
print('Target MLE: [{:.4f}, {:.4f}]'.format(x_obs.mean(), x_obs.std()))
# check hessians for positive definite
print('First {}'.format(shess(obs_hess[0], MAX_CHARS)))
print('Final {}'.format(shess(obs_hess[-1], MAX_CHARS)))
print('All Hessians are PD: {}'
.format(np.all([np.all(np.linalg.eigvals(h) > 0) for h in obs_hess])))
# visualize results
plot_canonical_gauss(x_obs, obs_mu, obs_sigma, obs_loss,
title='canonical params, adam, alpha = {}'
.format(LEARNING_RATE))