我正在使用python 2.7并尝试更好地了解张量流。
我正在使用以下代码尝试在mnist数据上训练一个自动编码器,当我使用sigmoid激活时,它gerelizes ok(90%),但是当我尝试relu它只是随机的。
最接近我found,但我找不到解决方案。
我做错了什么?我应该加辍学吗?也许成本函数或优化器对relu不好?
# Import MNIST data
from tensorflow.examples.tutorials.mnist import input_data
mnist = input_data.read_data_sets("MNIST_data", one_hot=True)
# Parameters
learning_rate = 0.01
training_epochs = 60
batch_size = 256
display_step = 1
examples_to_show = 10
# Network Parameters
n_hidden_1 = 256 # 1st layer num features
#n_hidden_1 = 400
n_hidden_2 = 128 # 2nd layer num features
#n_hidden_2 = 250
n_hidden_3 = 60
#n_hidden_2 = 30
n_input = 784 # MNIST data input (img shape: 28*28)
# tf Graph input (only pictures)
X = tf.placeholder("float", [None, n_input])
keep_prob = tf.placeholder("float", None)
#keep_prob = tf.placeholder(tf.float32)
weights = {
'encoder_h1': tf.Variable(tf.random_normal([n_input, n_hidden_1])),
'encoder_h2': tf.Variable(tf.random_normal([n_hidden_1, n_hidden_2])),
'encoder_h3': tf.Variable(tf.random_normal([n_hidden_2, n_hidden_3])),
'decoder_h1': tf.Variable(tf.random_normal([n_hidden_3, n_hidden_2])),
'decoder_h2': tf.Variable(tf.random_normal([n_hidden_2, n_hidden_1])),
'decoder_h3': tf.Variable(tf.random_normal([n_hidden_1, n_input])),
}
biases = {
'encoder_b1': tf.Variable(tf.random_normal([n_hidden_1])),
'encoder_b2': tf.Variable(tf.random_normal([n_hidden_2])),
'encoder_b3': tf.Variable(tf.random_normal([n_hidden_3])),
'decoder_b1': tf.Variable(tf.random_normal([n_hidden_2])),
'decoder_b2': tf.Variable(tf.random_normal([n_hidden_1])),
'decoder_b3': tf.Variable(tf.random_normal([n_input])),
}
# Building the encoder
def encoder(x):
# Encoder Hidden layer with sigmoid activation #1
layer_1 = tf.nn.sigmoid(tf.add(tf.matmul(x, weights['encoder_h1']),
biases['encoder_b1']))
# Decoder Hidden layer with sigmoid activation #2
dropout1 = tf.nn.dropout(layer_1, keep_prob)
layer_2 = tf.nn.sigmoid(tf.add(tf.matmul(layer_1, weights['encoder_h2']),
biases['encoder_b2']))
layer_3 = tf.nn.sigmoid(tf.add(tf.matmul(layer_2, weights['encoder_h3']),
biases['encoder_b3']))
return layer_3
# Building the decoder
def decoder(x):
# Encoder Hidden layer with sigmoid activation #1
layer_1 = tf.nn.sigmoid(tf.add(tf.matmul(x, weights['decoder_h1']),
biases['decoder_b1']))
# Decoder Hidden layer with sigmoid activation #2
layer_2 = tf.nn.sigmoid(tf.add(tf.matmul(layer_1, weights['decoder_h2']),
biases['decoder_b2']))
layer_3 = tf.nn.sigmoid(tf.add(tf.matmul(layer_2, weights['decoder_h3']),
biases['decoder_b3']))
return layer_3
# Construct model
encoder_op = encoder(X)
decoder_op = decoder(encoder_op)
# Prediction
y_pred = decoder_op
x_encode = encoder_op
# Targets (Labels) are the input data.
y_true = X
# Define loss and optimizer, minimize the squared error
cost = tf.reduce_mean(tf.pow(y_true - y_pred, 2))
optimizer = tf.train.RMSPropOptimizer(learning_rate).minimize(cost)
#optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost)
# Initializing the variables
init = tf.global_variables_initializer()
# Launch the graph
with tf.Session() as sess:
sess.run(init)
print("num examples are ", mnist.train.num_examples, mnist.validation.num_examples, mnist.test.num_examples)
total_batch = int(mnist.train.num_examples/batch_size)
# Training cycle
for epoch in range(training_epochs):
# Loop over all batches
for i in range(total_batch):
batch_xs, batch_ys = mnist.train.next_batch(batch_size)
# Run optimization op (backprop) and cost op (to get loss value)
_, c = sess.run([optimizer, cost], feed_dict={X: batch_xs})
# Display logs per epoch step
if epoch % display_step == 0:
print("Epoch:", '%04d' % (epoch+1),
"cost=", "{:.9f}".format(c))
print("Optimization Finished!")
# Applying encode and decode over test set
encode_decode = sess.run(
y_pred, feed_dict={X: mnist.test.images[:examples_to_show]})
encoded_data = sess.run(x_encode, feed_dict={X: mnist.test.images})
distance_matrix = scipy.spatial.distance.squareform(pdist(encoded_data))
d_m_2 = distance_matrix[:,:]
np.fill_diagonal(d_m_2,np.inf)
labels = np.argmax(mnist.test.labels,1) #these are the labels!
predicate = labels[np.argmin(d_m_2,1)] #get the indecies of the closest data sample
print ("this is the ammount of coorect clasificcations in the test set", np.sum(labels==predicate)) #count how many similar values are there!
谢谢!
答案 0 :(得分:2)
也许ReLU正在努力应对负输入值,因为它被定义为R(x):= max(0,x)。因此,如果输入为负,则R(x)= 0,并且梯度也将为零。因此,您的优化器不知道如何更新参数。你可以尝试使用像tf.random_normal(shape=..., mean=0.5, stddev=0.2)
那样积极的东西初始化你的权重。也许这会减少这个问题。