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NameError: name 'train_gen' is not defined

I'm new to python and tensorflow. I'm now testing Improved WGAN code from https://github.com/igul222/improved_wgan_training
After adjusting the code to python 3.6, it still gives "NameError: name 'train_gen' is not defined" when I ran it, although there wasn't warning from pylint.
Can anyone help me with it?
The version of python I'm using is 3.6. There were many syntax differences from 2.7. I've already changed a lot to make it work. And I am running Tensorflow in a virtual environment. Still couldn't figure out this one.
import os, sys
sys.path.append(os.getcwd())
import time
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import numpy as np
import sklearn.datasets
import tensorflow as tf
import tflib as lib
import tflib.ops.linear
import tflib.ops.conv2d
import tflib.ops.batchnorm
import tflib.ops.deconv2d
import tflib.save_images
import tflib.mnist
import tflib.plot
MODE = 'wgan-gp' # dcgan, wgan, or wgan-gp
DIM = 64 # Model dimensionality
BATCH_SIZE = 50 # Batch size
CRITIC_ITERS = 5 # For WGAN and WGAN-GP, number of critic iters per gen iter
LAMBDA = 10 # Gradient penalty lambda hyperparameter
ITERS = 200000 # How many generator iterations to train for
OUTPUT_DIM = 784 # Number of pixels in MNIST (28*28)
lib.print_model_settings(locals().copy())
def LeakyReLU(x, alpha=0.2):
return tf.maximum(alpha*x, x)
def ReLULayer(name, n_in, n_out, inputs):
output = lib.ops.linear.Linear(
name+'.Linear',
n_in,
n_out,
inputs,
initialization='he'
)
return tf.nn.relu(output)
def LeakyReLULayer(name, n_in, n_out, inputs):
output = lib.ops.linear.Linear(
name+'.Linear',
n_in,
n_out,
inputs,
initialization='he'
)
return LeakyReLU(output)
def Generator(n_samples, noise=None):
if noise is None:
noise = tf.random_normal([n_samples, 128])
output = lib.ops.linear.Linear('Generator.Input', 128, 4*4*4*DIM, noise)
if MODE == 'wgan':
output = lib.ops.batchnorm.Batchnorm('Generator.BN1', [0], output)
output = tf.nn.relu(output)
output = tf.reshape(output, [-1, 4*DIM, 4, 4])
output = lib.ops.deconv2d.Deconv2D('Generator.2', 4*DIM, 2*DIM, 5, output)
if MODE == 'wgan':
output = lib.ops.batchnorm.Batchnorm('Generator.BN2', [0,2,3], output)
output = tf.nn.relu(output)
output = output[:,:,:7,:7]
output = lib.ops.deconv2d.Deconv2D('Generator.3', 2*DIM, DIM, 5, output)
if MODE == 'wgan':
output = lib.ops.batchnorm.Batchnorm('Generator.BN3', [0,2,3], output)
output = tf.nn.relu(output)
output = lib.ops.deconv2d.Deconv2D('Generator.5', DIM, 1, 5, output)
output = tf.nn.sigmoid(output)
return tf.reshape(output, [-1, OUTPUT_DIM])
def Discriminator(inputs):
output = tf.reshape(inputs, [-1, 1, 28, 28])
output = lib.ops.conv2d.Conv2D('Discriminator.1',1,DIM,5,output,stride=2)
output = LeakyReLU(output)
output = lib.ops.conv2d.Conv2D('Discriminator.2', DIM, 2*DIM, 5, output, stride=2)
if MODE == 'wgan':
output = lib.ops.batchnorm.Batchnorm('Discriminator.BN2', [0,2,3], output)
output = LeakyReLU(output)
output = lib.ops.conv2d.Conv2D('Discriminator.3', 2*DIM, 4*DIM, 5, output, stride=2)
if MODE == 'wgan':
output = lib.ops.batchnorm.Batchnorm('Discriminator.BN3', [0,2,3], output)
output = LeakyReLU(output)
output = tf.reshape(output, [-1, 4*4*4*DIM])
output = lib.ops.linear.Linear('Discriminator.Output', 4*4*4*DIM, 1, output)
return tf.reshape(output, [-1])
real_data = tf.placeholder(tf.float32, shape=[BATCH_SIZE, OUTPUT_DIM])
fake_data = Generator(BATCH_SIZE)
disc_real = Discriminator(real_data)
disc_fake = Discriminator(fake_data)
gen_params = lib.params_with_name('Generator')
disc_params = lib.params_with_name('Discriminator')
if MODE == 'wgan':
gen_cost = -tf.reduce_mean(disc_fake)
disc_cost = tf.reduce_mean(disc_fake) - tf.reduce_mean(disc_real)
gen_train_op = tf.train.RMSPropOptimizer(
learning_rate=5e-5
).minimize(gen_cost, var_list=gen_params)
disc_train_op = tf.train.RMSPropOptimizer(
learning_rate=5e-5
).minimize(disc_cost, var_list=disc_params)
clip_ops = []
for var in lib.params_with_name('Discriminator'):
clip_bounds = [-.01, .01]
clip_ops.append(
tf.assign(
var,
tf.clip_by_value(var, clip_bounds[0], clip_bounds[1])
)
)
clip_disc_weights = tf.group(*clip_ops)
elif MODE == 'wgan-gp':
gen_cost = -tf.reduce_mean(disc_fake)
disc_cost = tf.reduce_mean(disc_fake) - tf.reduce_mean(disc_real)
alpha = tf.random_uniform(
shape=[BATCH_SIZE,1],
minval=0.,
maxval=1.
)
differences = fake_data - real_data
interpolates = real_data + (alpha*differences)
gradients = tf.gradients(Discriminator(interpolates), [interpolates])[0]
slopes = tf.sqrt(tf.reduce_sum(tf.square(gradients), reduction_indices=[1]))
gradient_penalty = tf.reduce_mean((slopes-1.)**2)
disc_cost += LAMBDA*gradient_penalty
gen_train_op = tf.train.AdamOptimizer(
learning_rate=1e-4,
beta1=0.5,
beta2=0.9
).minimize(gen_cost, var_list=gen_params)
disc_train_op = tf.train.AdamOptimizer(
learning_rate=1e-4,
beta1=0.5,
beta2=0.9
).minimize(disc_cost, var_list=disc_params)
clip_disc_weights = None
elif MODE == 'dcgan':
gen_cost = tf.reduce_mean(tf.nn.sigmoid_cross_entropy_with_logits(
disc_fake,
tf.ones_like(disc_fake)
))
disc_cost = tf.reduce_mean(tf.nn.sigmoid_cross_entropy_with_logits(
disc_fake,
tf.zeros_like(disc_fake)
))
disc_cost += tf.reduce_mean(tf.nn.sigmoid_cross_entropy_with_logits(
disc_real,
tf.ones_like(disc_real)
))
disc_cost /= 2.
gen_train_op = tf.train.AdamOptimizer(
learning_rate=2e-4,
beta1=0.5
).minimize(gen_cost, var_list=gen_params)
disc_train_op = tf.train.AdamOptimizer(
learning_rate=2e-4,
beta1=0.5
).minimize(disc_cost, var_list=disc_params)
clip_disc_weights = None
# For saving samples
fixed_noise = tf.constant(np.random.normal(size=(128, 128)).astype('float32'))
fixed_noise_samples = Generator(128, noise=fixed_noise)
def generate_image(frame, true_dist):
samples = session.run(fixed_noise_samples)
lib.save_images.save_images(
samples.reshape((128, 28, 28)),
'samples_{}.png'.format(frame)
)
# Dataset iterator
train_gen, dev_gen, test_gen = lib.mnist.load(BATCH_SIZE, BATCH_SIZE)
def inf_train_gen():
while True:
for images, targets in train_gen():
yield images
# Train loop
with tf.Session() as session:
session.run(tf.initialize_all_variables())
gen = inf_train_gen()
for iteration in range(ITERS):
start_time = time.time()
if iteration > 0:
_ = session.run(gen_train_op)
if MODE == 'dcgan':
disc_iters = 1
else:
disc_iters = CRITIC_ITERS
for i in range(disc_iters):
_data = gen.__next__()
_disc_cost, _ = session.run(
[disc_cost, disc_train_op],
feed_dict={real_data: _data}
)
if clip_disc_weights is not None:
_ = session.run(clip_disc_weights)
lib.plot.plot('train disc cost', _disc_cost)
lib.plot.plot('time', time.time() - start_time)
# Calculate dev loss and generate samples every 100 iters
if iteration % 100 == 99:
dev_disc_costs = []
for images,_ in dev_gen():
_dev_disc_cost = session.run(
disc_cost,
feed_dict={real_data: images}
)
dev_disc_costs.append(_dev_disc_cost)
lib.plot.plot('dev disc cost', np.mean(dev_disc_costs))
generate_image(iteration, _data)
# Write logs every 100 iters
if (iteration < 5) or (iteration % 100 == 99):
lib.plot.flush()
lib.plot.tick()
This is the section containing the error name.
# Dataset iterator
train_gen, dev_gen, test_gen = lib.mnist.load(BATCH_SIZE, BATCH_SIZE)
def inf_train_gen():
while True:
for images, targets in train_gen():
yield images
And here is the error.
Traceback (most recent call last):
File "<stdin>", line 13, in <module>
File "<stdin>", line 3, in inf_train_gen
NameError: name 'train_gen' is not defined

Attempt 1:
I believe it's just because you are saying for images, targets in train_gen(): when you should be saying for images, targets in train_gen:
In a nutshell, the brackets suggest you are calling a function, which leads Python to raise the exception NameError: name 'train_gen' is not defined because there is no function with the name train_gen defined.
In the future, your code should be minimal, because you have pasted an enormous amount of code which makes it very hard to debug/see what you're doing.
Attempt 2:
Upon second review of the code (this is a good reason why you need to make your examples as small as possible), I have realised that is is possible you are maybe importing this code from elsewhere?
When you are making the first assignment to train_gen this is outside the function scope. It is possible then that when you go to call the function train_gen is no longer defined, which is why you get your error. This can occur for a number of reasons. After having reviewed the code a little there are various issues I can see (bad practice mostly).
It is generally not a good idea to use global variables within a function as you have in inf_train_gen, if a function needs an argument to run properly, then it should be passed as an argument. This is because if we have a problem with a variable (as we do now) we can normally see where this variable comes from and what uses it, but if all function rely on the globally scoped variable, any number of functions could delete it, change it, etc.
Right now I have no idea what has happened to the variable train_gen, I would suggest printing out the variable at different intervals and seeing if you can see which function call is causing issues and in the future stay away from globally scoped variables unless absolutely necessary, it makes it near-impossible to debug.

TF: how to solve ValueError: Variable ...weight already exists, disallowed. Did you mean to set reuse=True

I build an Inverse Compositional CNN but it reports errors as bellows:
ValueError: Variable left_src_tgt_warp/ICSTN/icnv1/weight already exists, disallowed. Did you mean to set reuse=True in VarScope? Originally defined at:
I find that using tf.reset_default_graph() can solve this problem. But I do not know where I should add it.
for l in range(opt.warpN):
with tf.variable_scope("ICSTN", reuse=l > 0) as sc:
end_points_collection = sc.original_name_scope + '_end_points'
with slim.arg_scope([slim.conv2d, slim.conv2d_transpose],
normalizer_fn=slim.batch_norm,
weights_regularizer=slim.l2_regularizer(0.05),
normalizer_params=batch_norm_params,
activation_fn=tf.nn.relu,
outputs_collections=end_points_collection):
imageWarp = inverse_warp(
inputImage,
depth,
pM,
intrinsics,
intrinsics_inv)
imageWarpAll.append(imageWarp)
feat = tf.reshape(imageWarp, [batch_size, H, W, C])
print('feat shape:', feat.get_shape())
print('pM_ini:', pM.get_shape())
with tf.variable_scope("icnv1"):
feat = conv2Layer(opt, feat, 4)
feat = tf.nn.relu(feat)
with tf.variable_scope("icnv2"):
feat = conv2Layer(opt, feat, 8)
feat = tf.nn.relu(feat)
feat = tf.nn.max_pool(feat, ksize=[1, 2, 2, 1], strides=[1, 2, 2, 1], padding="VALID")
feat = tf.reshape(feat, [opt.batch_size, -1])
with tf.variable_scope("fc3"):
feat = linearLayer(opt, feat, 48)
feat = tf.nn.relu(feat)
with tf.variable_scope("fc4"):
feat = linearLayer(opt, feat, 6, final=True)
dp = tf.reshape(feat, [-1, 6])
print('dp: ', dp.get_shape())
dpM = pose_vec2mat(dp)
pM = tf.matmul(dpM, pM)
imageWarp = inverse_warp(
inputImage,
depth,
pM,
intrinsics,
intrinsics_inv)
imageWarpAll.append(imageWarp)
return imageWarpAll, pM
def build_train_graph():
with tf.name_scope("cnn1"):...
with tf.name_scope("cnn2"):...
with tf.name_scope("Inverse Compositional CNN"):...
def train(self, opt):
with tf.variable_scope(tf.get_variable_scope()):
for i in range(opt.num_gpus):
print('gpu:', i)
with tf.device('/gpu:%d' % i):
self.build_train_graph(L_img_splits[i], R_img_splits[i], L_cam2pix_splits[i], L_pix2cam_splits[i],
R_cam2pix_splits[i], R_pix2cam_splits[i], L_sca_splits[i], R_sca_splits[i],
reuse_variables)
self.collect_summaries(i)
tower_losses.append(self.total_loss)
reuse_variables = True
grads = opt_step.compute_gradients(self.total_loss)
tower_grads.append(grads)
grads = average_gradients(tower_grads)
apply_gradient_op = opt_step.apply_gr`enter code here`adients(grads, global_step=global_step)
incr_global_step = tf.assign(global_step, global_step + 1)
total_loss = tf.reduce_mean(tower_losses)
tf.summary.scalar('learning_rate', learning_rate, ['model_0'])
tf.summary.scalar('total_loss', total_loss, ['model_0'])
summary_op = tf.summary.merge_all('model_0')
# self.collect_summaries()
# SESSION
config = tf.ConfigProto(allow_soft_placement=True)
config.gpu_options.allow_growth = True
sess = tf.Session(config=config)
# SAVER
summary_writer = tf.summary.FileWriter(
opt.checkpoint_dir + '/s%.1d_%.3d/' % (opt.seq_length, opt.img_height) + opt.model_name, sess.graph)
self.saver = tf.train.Saver()
# COUNT PARAM
total_num_parameters = 0
for variable in tf.trainable_variables():
total_num_parameters += np.array(variable.get_shape().as_list()).prod()
print("number of trainable parameters: {}".format(total_num_parameters))
# INIT
sess.run(tf.global_variables_initializer())
sess.run(tf.local_variables_initializer())
coordinator = tf.train.Coordinator()
threads = tf.train.start_queue_runners(sess=sess, coord=coordinator)
# LOAD CHECKPOINT IF SET
if opt.continue_train:
print("Resume training from previous checkpoint")
checkpoint = tf.train.latest_checkpoint(
os.path.join(opt.checkpoint_dir, 's%.1d_%.3d' % (opt.seq_length, opt.img_height), opt.model_name))
self.saver.restore(sess, checkpoint)
if opt.re_train:
sess.run(global_step.assign(0))

It's because of the for loop in the first part of the code that's possibly missing function name.
The loop tries to create the left_src_tgt_warp/ICSTN/icnv1/weight (same for icnv2 and so on):
def foo(num_layers):
opt = tf.placeholder(tf.float32, [None, 64])
for i in range(num_layers):
with tf.variable_scope("icnv1"):
feat = tf.layers.dense(opt, units=1, activation=tf.nn.relu)
foo(5)
ValueError: Variable icnv1/dense/kernel already exists, disallowed. Did you mean to set reuse=True
You need distinct names for Variables. One way to achieve this is like this:
def foo(num_layers):
opt = tf.placeholder(tf.float32, [None, 64])
for i in range(num_layers):
with tf.variable_scope("icnv1_layer_{}".format(i)):
feat = tf.layers.dense(opt, units=1, activation=tf.nn.relu)
we now have distinct names for each, icnv1_layer_1, icnv1_layer_2, etc. Depending on the depth.
Unless of course, you want a shared weights (e.g. it's the same layer, updates as one). In that case just set:
with tf.variable_scope("icnv1", reuse=tf.AUTO_REUSE):

I'm using Jupyter Notebooks to run my models and I recently realize that this error was occuring due to the fact that variables of my model was been saved on an "outter context". So when I restart kernel (and thus clean all my workspace variable) and run all cells the error gone away.

Understanding how a TensorFlow model as a class and a TensorFlow Session interact

I have been using TensorFlow for a reasonable length of time now. and believed I had a thorough understanding of how a TensorFlow graph works and executes within a session. However, I have written all of my TensorFlow models in a script-like fashion as such:
import tensorflow as tf
import DataWorker
import Constants
x = tf.placeholder(tf.float32, [None, Constants.sequenceLength, DataWorker.numFeatures])
y = tf.placeholder(tf.float32, [None, 1])
xTensors = tf.unstack(x, axis=1) # [seqLength tensors of shape (batchSize, numFeatures)]
W = tf.Variable(tf.random_normal([Constants.numHidden, 1])) # Weighted matrix
b = tf.Variable(tf.random_normal([1])) # Bias
cell = tf.contrib.rnn.BasicLSTMCell(Constants.numHidden, forget_bias=Constants.forgetBias)
outputs, finalState = tf.nn.static_rnn(cell, xTensors, dtype=tf.float32)
# predictions = [tf.add(tf.matmul(output, W), b) for output in outputs] # List of predictions after each time step
prediction = tf.add(tf.matmul(outputs[-1], W), b) # Prediction after final time step
prediction = tf.tanh(prediction) # Activation
mse = tf.losses.mean_squared_error(predictions=prediction, labels=y) # Mean loss over entire batch
accuracy = tf.reduce_mean(1 - (tf.abs(y - prediction) / DataWorker.labelRange)) # Accuracy over entire batch
optimiser = tf.train.AdamOptimizer(Constants.learningRate).minimize(mse) # Backpropagation
with tf.Session() as session:
session.run(tf.global_variables_initializer())
# #############################################
# TRAINING
# #############################################
for epoch in range(Constants.numEpochs):
print("***** EPOCH:", epoch + 1, "*****\n")
IDPointer, TSPointer = 0, 0 # Pointers to current ID and timestamp
epochComplete = False
batchNum = 0
while not epochComplete:
batchNum += 1
batchX, batchY, IDPointer, TSPointer, epochComplete = DataWorker.generateBatch(IDPointer, TSPointer, isTraining=True)
dict = {x: batchX, y: batchY}
session.run(optimiser, dict)
if batchNum % 1000 == 0 or epochComplete:
batchLoss = session.run(mse, dict)
batchAccuracy = session.run(accuracy, dict)
print("Iteration:", batchNum)
print(batchLoss)
print(str("%.2f" % (batchAccuracy * 100) + "%\n"))
# #############################################
# TESTING
# #############################################
testX, testY, _, _, _ = DataWorker.generateBatch(0, 0, isTraining=False)
testAccuracy = session.run(accuracy, {x: testX, y: testY})
print("Testing Accuracy:", str("%.2f" % (testAccuracy * 100) + "%"))
But now, for practicality and readability, I want to implement my model as a class, but have encountered many problems with initializing my variables, etc.
This is the closest I have got to implementing the above example using my own LSTM class
Model.py
import tensorflow as tf
import Constants
import DataWorker # Remove this dependency
class LSTM():
"""docstring."""
def __init__(self,
inputDimensionList,
outputDimensionList,
numLayers=Constants.numLayers,
numHidden=Constants.numHidden,
learningRate=Constants.learningRate,
forgetBias=Constants.forgetBias
):
"""docstring."""
self.batchInputs = tf.placeholder(tf.float32, [None] + inputDimensionList)
self.batchLabels = tf.placeholder(tf.float32, [None] + outputDimensionList)
self.weightedMatrix = tf.Variable(tf.random_normal([numHidden] + outputDimensionList))
self.biasMatrix = tf.Variable(tf.random_normal(outputDimensionList))
self.cell = tf.contrib.rnn.BasicLSTMCell(numHidden, forget_bias=forgetBias)
self.numLayers = numLayers
self.numHidden = numHidden
self.learningRate = learningRate
self.forgetBias = forgetBias
self.batchDict = {}
self.batchInputTensors = None
self.batchOutputs = None # All needed as instance variables?
self.batchFinalStates = None
self.batchPredictions = None
self.batchLoss = None
self.batchAccuracy = None
self.initialised = False
self.session = tf.Session()
# Take in activation, loss and optimiser FUNCTIONS as args
def execute(self, command):
"""docstring."""
return self.session.run(command, self.batchDict)
def setBatchDict(self, inputs, labels):
"""docstring."""
self.batchDict = {self.batchInputs: inputs, self.batchLabels: labels}
self.batchInputTensors = tf.unstack(self.batchInputs, axis=1)
def processBatch(self):
"""docstring."""
self.batchOutputs, self.batchFinalState = tf.nn.static_rnn(self.cell, self.batchInputTensors, dtype=tf.float32)
pred = tf.tanh(tf.add(tf.matmul(self.batchOutputs[-1], self.weightedMatrix), self.biasMatrix))
mse = tf.losses.mean_squared_error(predictions=pred, labels=self.batchLabels)
optimiser = tf.train.AdamOptimizer(self.learningRate).minimize(mse)
if not self.initialised:
self.session.run(tf.global_variables_initializer())
self.initialised = True
with tf.variable_scope("model") as scope:
if self.initialised:
scope.reuse_variables()
self.execute(optimiser)
self.batchPredictions = self.execute(pred)
self.batchLoss = self.execute(tf.losses.mean_squared_error(predictions=self.batchPredictions, labels=self.batchLabels))
self.batchAccuracy = self.execute(tf.reduce_mean(1 - (tf.abs(self.batchLabels - self.batchPredictions) / DataWorker.labelRange)))
return self.batchPredictions, self.batchLabels, self.batchLoss, self.batchAccuracy
def kill(self):
"""docstring."""
self.session.close()
This class is quite messy, especially processBatch() as I have just been trying to get it to work before refining it.
I then run my model here:
Main.py
import DataWorker
import Constants
from Model import LSTM
inputDim = [Constants.sequenceLength, DataWorker.numFeatures]
outputDim = [1]
lstm = LSTM(inputDimensionList=inputDim, outputDimensionList=outputDim)
# #############################################
# TRAINING
# #############################################
for epoch in range(Constants.numEpochs):
print("***** EPOCH:", epoch + 1, "*****\n")
IDPointer, TSPointer = 0, 0 # Pointers to current ID and timestamp
epochComplete = False
batchNum = 0
while not epochComplete:
batchNum += 1
batchX, batchY, IDPointer, TSPointer, epochComplete = DataWorker.generateBatch(IDPointer, TSPointer, isTraining=True)
lstm.setBatchDict(batchX, batchY)
batchPredictions, batchLabels, batchLoss, batchAccuracy = lstm.runBatch()
if batchNum % 1000 == 0 or epochComplete:
print("Iteration:", batchNum)
print("Pred:", batchPredictions[-1], "\tLabel:", batchLabels[-1])
print("Loss:", batchLoss)
print("Accuracy:", str("%.2f" % (batchAccuracy * 100) + "%\n"))
# #############################################
# TESTING
# #############################################
testX, testY, _, _, _ = DataWorker.generateBatch(0, 0, isTraining=False)
lstm.setBatchDict(testX, testY)
_, _, _, testAccuracy = lstm.runBatch()
print("Testing Accuracy:", str("%.2f" % (testAccuracy * 100) + "%"))
lstm.kill()
A single passthrough of the graph is executed fine, when all the variables are initialized, but it is on the second iteration where I get the error
ValueError: Variable rnn/basic_lstm_cell/kernel/Adam/ already exists, disallowed. Did you mean to set reuse=True in VarScope? Originally defined at:
optimiser = tf.train.AdamOptimizer(self.learningRate).minimize(mse)
I Googled this problem and learned that using scope.reuse_variables() should stop it trying to initialize the AdamOptimizer a second time, but cleary this isn't working how I have implemented it. How can I fix this issue?
As a side note, is my method of creating the TensorFlow session as an instance variable within my LSTM class acceptable, or should I create the session in Main and then pass it into the LSTM instance?

In general I wrap anything that creates variables under the hood with tf.make_template when doing object oriented model building.
However, you should avoid adding ops to the graph in a training loop, which looks like it's happening here. They will build up and cause problems, and likely give you incorrect results. Instead, define the graph (with inputs from tf.data, placeholders, or queues) and only loop over a session.run call. Even better, structure your code as an Estimator and this will be enforced.

Creating custom error function in CNTK

This is part of my current python code for NN training in python using CNTK module
batch_axis = C.Axis.default_batch_axis()
input_seq_axis = C.Axis.default_dynamic_axis()
input_dynamic_axes = [batch_axis, input_seq_axis]
input_dynamic_axes2 = [batch_axis, input_seq_axis]
input = C.input_variable(n_ins, dynamic_axes=input_dynamic_axes, dtype=numpy.float32)
output = C.input_variable(n_outs, dynamic_axes=input_dynamic_axes2, dtype=numpy.float32)
dnn_model = cntk_model.create_model(input, hidden_layer_type, hidden_layer_size, n_outs)
loss = C.squared_error(dnn_model, output)
error = C.squared_error(dnn_model, output)
lr_schedule = C.learning_rate_schedule(current_finetune_lr, C.UnitType.minibatch)
momentum_schedule = C.momentum_schedule(current_momentum)
learner = C.adam(dnn_model.parameters, lr_schedule, momentum_schedule, unit_gain = False, l1_regularization_weight=l1_reg, l2_regularization_weight= l2_reg)
trainer = C.Trainer(dnn_model, (loss, error), [learner])
And here is code for creating NN model
def create_model(features, hidden_layer_type, hidden_layer_size, n_out):
logger.debug('Creating cntk model')
assert len(hidden_layer_size) == len(hidden_layer_type)
n_layers = len(hidden_layer_size)
my_layers = list()
for i in xrange(n_layers):
if(hidden_layer_type[i] == 'TANH'):
my_layers.append(C.layers.Dense(hidden_layer_size[i], activation=C.tanh, init=C.layers.glorot_uniform()))
elif (hidden_layer_type[i] == 'LSTM'):
my_layers.append(C.layers.Recurrence(C.layers.LSTM(hidden_layer_size[i])))
else:
raise Exception('Unknown hidden layer type')
my_layers.append(C.layers.Dense(n_out, activation=None))
my_model = C.layers.Sequential([my_layers])
my_model = my_model(features)
return my_model
Now, I would like to change a backpropagation, so when the error is calculated not direct network output is used, but the output after some additional calculation. I tried to define something like this
def create_error_function(self, prediction, target):
prediction_denorm = C.element_times(prediction, self.std_vector)
prediction_denorm = C.plus(prediction_denorm, self.mean_vector)
prediction_denorm_rounded = C.round(C.element_times(prediction_denorm[0:5], C.round(prediction_denorm[5])))
prediction_denorm_rounded = C.element_divide(prediction_denorm_rounded, C.round(prediction_denorm[5]))
prediction_norm = C.minus(prediction_denorm_rounded, self.mean_vector[0:5])
prediction_norm = C.element_divide(prediction_norm, self.std_vector[0:5])
first = C.squared_error(prediction_norm, target[0:5])
second = C.minus(C.round(prediction_denorm[5]), self.mean_vector[5])
second = C.element_divide(second, self.std_vector[5])
return C.plus(first, C.squared_error(second, target[5]))
and use it instead standard squared_error.
And the part for NN training
dnn_model = cntk_model.create_model(input, hidden_layer_type, hidden_layer_size, n_outs)
error_function = cntk_model.ErrorFunction(cmp_mean_vector, cmp_std_vector)
loss = error_function.create_error_function(dnn_model, output)
error = error_function.create_error_function(dnn_model, output)
lr_schedule = C.learning_rate_schedule(current_finetune_lr, C.UnitType.minibatch)
momentum_schedule = C.momentum_schedule(current_momentum)
learner = C.adam(dnn_model.parameters, lr_schedule, momentum_schedule, unit_gain = False, l1_regularization_weight=l1_reg,
l2_regularization_weight= l2_reg)
trainer = C.Trainer(dnn_model, (loss, error), [learner])
trainer.train_minibatch({input: temp_train_x, output: temp_train_y})
But after two epochs I start gettting always the same average loss, as my network is not learning

Every time you want to change how backprop works, you need to use stop_gradient. This is the only function whose gradient is different from the gradient of the operation of the forward pass. In the forward pass stop_gradient acts as identity. In the backward pass it blocks the gradient from propagating.
To do an operation f(x) on some x in the forward pass and pretend as if it never happened in the backward pass you need to do something like:
C.stop_gradient(f(x) - x) + x. In your case that would be
norm_features = C.stop_gradient(features/normalization - features) + features

tensorflow embeddings don't exist after first RNN example

I've setup a print statement and I've noticed that for the first batch when feeding an RNN, the embeddings exist, but after the second batch they don't and I get the following error:
ValueError: Variable RNNLM/RNNLM/Embedding/Adam_2/ does not exist, or was not created with tf.get_variable(). Did you mean to set reuse=None in VarScope?
Here is my code for generating the embeddings:
def add_embedding(self):
with tf.device('/gpu:0'):
embedding = tf.get_variable("Embedding", [len(self.vocab), self.config.embed_size])
e_x = tf.nn.embedding_lookup(embedding, self.input_placeholder)
inputs = [tf.squeeze(s, [1]) for s in tf.split(1, self.config.num_steps, e_x)]
return inputs
Here is how the model is seutp, this is where I suspect the problem lies
def model(self, inputs):
with tf.variable_scope("input_drop"):
inputs_drop = [tf.nn.dropout(i, self.dropout_placeholder) for i in inputs]
with tf.variable_scope("RNN") as scope:
self.initial_state = tf.zeros([self.config.batch_size, self.config.hidden_size], tf.float32)
state = self.initial_state
states = []
for t, e in enumerate(inputs_drop):
print "t is {0}".format(t)
if t > 0:
scope.reuse_variables()
H = tf.get_variable("Hidden", [self.config.hidden_size, self.config.hidden_size])
I = tf.get_variable("I", [self.config.embed_size, self.config.hidden_size])
b_1 = tf.get_variable("b_1", (self.config.hidden_size,))
state = tf.sigmoid(tf.matmul(state, H) + tf.matmul(e, I) + b_1)
states.append(state)
with tf.variable_scope("output_dropout"):
rnn_outputs = [tf.nn.dropout(o, self.dropout_placeholder) for o in states]
return rnn_outputs
The issue arises when I get to the loss function, defined as follows
def add_training_op(self, loss):
opt = tf.train.AdamOptimizer(self.config.lr)
train_op = opt.minimize(loss)
return train_op
EDIT: Here is some updated code to help everyone out
def __init__(self, config):
self.config = config
self.load_data(debug=False)
self.add_placeholders()
self.inputs = self.add_embedding()
self.rnn_outputs = self.add_model(self.inputs)
self.outputs = self.add_projection(self.rnn_outputs)
self.predictions = [tf.nn.softmax(tf.cast(o, 'float64')) for o in self.outputs]
output = tf.reshape(tf.concat(1, self.outputs), [-1, len(self.vocab)])
self.calculate_loss = self.add_loss_op(output)
self.train_step = self.add_training_op(self.calculate_loss)
Here are the other methods here, pertaining to add_projection and calculate_loss so we can rule them out.
def add_loss_op(self, output):
weights = tf.ones([self.config.batch_size * self.config.num_steps], tf.int32)
seq_loss = tf.python.seq2seq.sequence_loss(
[output],
tf.reshape(self.labels_placeholder, [-1]),
weights
)
tf.add_to_collection('total_loss', seq_loss)
loss = tf.add_n(tf.get_collection('total_loss'))
return loss
def add_projection(self, rnn_outputs):
with tf.variable_scope("Projection", initializer=tf.contrib.layers.xavier_initializer()) as scope:
U = tf.get_variable("U", [self.config.hidden_size, len(self.vocab)])
b_2 = tf.get_variable("b_2", [len(self.vocab)])
outputs = [tf.matmul(x, U) + b_2 for x in rnn_outputs]
return outputs
def train_RNNLM():
config = Config()
gen_config = deepcopy(config)
gen_config.batch_size = gen_config.num_steps = 1
with tf.variable_scope('RNNLM') as scope:
model = RNNLM_Model(config)
# This instructs gen_model to reuse the same variables as the model above
scope.reuse_variables()
gen_model = RNNLM_Model(gen_config)
init = tf.initialize_all_variables()
saver = tf.train.Saver()
with tf.Session() as session:
best_val_pp = float('inf')
best_val_epoch = 0
session.run(init)
for epoch in xrange(config.max_epochs):
print 'Epoch {}'.format(epoch)
start = time.time()
###
train_pp = model.run_epoch(
session, model.encoded_train,
train_op=model.train_step)
valid_pp = model.run_epoch(session, model.encoded_valid)
print 'Training perplexity: {}'.format(train_pp)
print 'Validation perplexity: {}'.format(valid_pp)
if valid_pp < best_val_pp:
best_val_pp = valid_pp
best_val_epoch = epoch
saver.save(session, './ptb_rnnlm.weights')
if epoch - best_val_epoch > config.early_stopping:
break
print 'Total time: {}'.format(time.time() - start)

Seems that the code is trying to create a new Adam Variable in each batch.
Possible that the add_training_op is called twice?
Also, the snippet of def add_training_op is incomplete since there is no return statement.

The problem turned out to be the following line of code:
model = RNNLM_Model(config)
# This instructs gen_model to reuse the same variables as the model above
scope.reuse_variables()
gen_model = RNNLM_Model(gen_config)
It turns out that the second model was an issue by using reuse_variables(). By removing this line by issues went away.