Prettytensor: Attempting to use uninitialized value - tensorflow

Question

I'm following these tutorials:
https://www.youtube.com/watch?v=wuo4JdG3SvU&list=PL9Hr9sNUjfsmEu1ZniY0XpHSzl5uihcXZ
and prettytensor is introduced in tutorial 4.
Following the tutorial, i wrote this code to run a small neural network:
import tensorflow as tf
# Use PrettyTensor to simplify Neural Network construction.
import prettytensor as pt
from tensorflow.examples.tutorials.mnist import input_data
data = input_data.read_data_sets('../data/MNIST/', one_hot=True)
# We know that MNIST images are 28 pixels in each dimension.
img_size = 28
# Images are stored in one-dimensional arrays of this length.
img_size_flat = img_size * img_size
# Tuple with height and width of images used to reshape arrays.
img_shape = (img_size, img_size)
# Number of colour channels for the images: 1 channel for gray-scale.
num_channels = 1
# Number of classes, one class for each of 10 digits.
num_classes = 10
# the placeholders
x = tf.placeholder(tf.float32, shape=[None, img_size_flat], name='x')
x_image = tf.reshape(x, [-1, img_size, img_size, num_channels])
y_true = tf.placeholder(tf.float32, shape=[None, 10], name='y_true')
# use prettyTensor to build the model
# this will give us the predictions and the loss functions
x_pretty = pt.wrap(x_image)
with pt.defaults_scope(activation_fn=tf.nn.relu):
y_pred, loss = x_pretty.\
conv2d(kernel=5, depth=16, name='layer_conv1').\
max_pool(kernel=2, stride=2).\
conv2d(kernel=5, depth=36, name='layer_conv2').\
max_pool(kernel=2, stride=2).\
flatten().\
fully_connected(size=128, name='layer_fc1').\
softmax_classifier(class_count=10, labels=y_true)
# the model optimizer
optimizer = tf.train.AdamOptimizer(learning_rate=1e-4).minimize(loss)
# the model testing
correct_prediction = tf.equal(tf.argmax(y_pred,1), tf.argmax(y_true,1))
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
# start the session
session = tf.InteractiveSession()
# Start the training
tf.global_variables_initializer().run(session = session)
train_batch_size = 64
for i in range(1000):
print("training batch ",i)
x_batch, y_true_batch = data.train.next_batch(train_batch_size)
session.run(optimizer, feed_dict={x:x_batch, y_true:y_true_batch})
When i tried to run it, I got the following error:
tensorflow.python.framework.errors_impl.FailedPreconditionError: Attempting to use uninitialized value layer_conv1/bias
[[Node: layer_conv1/bias/read = Identity[T=DT_FLOAT, _class=["loc:#layer_conv1/bias"], _device="/job:localhost/replica:0/task:0/cpu:0"](layer_conv1/bias)]]
Caused by op u'layer_conv1/bias/read', defined at:
File "/home/gal/Documents/Workspace/EclipseWorkspace/Melanoma Classification!/tutorial4/tutorial4Test.py", line 31, in <module>
the full error trace:
Traceback (most recent call last):
File "/home/gal/Documents/Workspace/EclipseWorkspace/Melanoma Classification!/tutorial4/tutorial4Test.py", line 55, in <module>
session.run(optimizer, feed_dict={x:x_batch, y_true:y_true_batch})
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 766, in run
run_metadata_ptr)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 964, in _run
feed_dict_string, options, run_metadata)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 1014, in _do_run
target_list, options, run_metadata)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 1034, in _do_call
raise type(e)(node_def, op, message)
tensorflow.python.framework.errors_impl.FailedPreconditionError: Attempting to use uninitialized value layer_conv1/bias
[[Node: layer_conv1/bias/read = Identity[T=DT_FLOAT, _class=["loc:#layer_conv1/bias"], _device="/job:localhost/replica:0/task:0/cpu:0"](layer_conv1/bias)]]
Caused by op u'layer_conv1/bias/read', defined at:
File "/home/gal/Documents/Workspace/EclipseWorkspace/Melanoma Classification!/tutorial4/tutorial4Test.py", line 31, in <module>
conv2d(kernel=5, depth=16, name='layer_conv1').\
File "/home/gal/anaconda2/lib/python2.7/site-packages/prettytensor/pretty_tensor_class.py", line 1981, in method
result = func(non_seq_layer, *args, **kwargs)
File "/home/gal/anaconda2/lib/python2.7/site-packages/prettytensor/pretty_tensor_image_methods.py", line 163, in __call__
y += self.variable('bias', [size[-1]], bias_init, dt=dtype)
File "/home/gal/anaconda2/lib/python2.7/site-packages/prettytensor/pretty_tensor_class.py", line 1695, in variable
collections=variable_collections)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 1024, in get_variable
custom_getter=custom_getter)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 850, in get_variable
custom_getter=custom_getter)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 346, in get_variable
validate_shape=validate_shape)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 331, in _true_getter
caching_device=caching_device, validate_shape=validate_shape)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 677, in _get_single_variable
expected_shape=shape)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variables.py", line 224, in __init__
expected_shape=expected_shape)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variables.py", line 370, in _init_from_args
self._snapshot = array_ops.identity(self._variable, name="read")
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/gen_array_ops.py", line 1424, in identity
result = _op_def_lib.apply_op("Identity", input=input, name=name)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/framework/op_def_library.py", line 759, in apply_op
op_def=op_def)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 2240, in create_op
original_op=self._default_original_op, op_def=op_def)
File "/home/gal/anaconda2/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 1128, in __init__
self._traceback = _extract_stack()
FailedPreconditionError (see above for traceback): Attempting to use uninitialized value layer_conv1/bias
[[Node: layer_conv1/bias/read = Identity[T=DT_FLOAT, _class=["loc:#layer_conv1/bias"], _device="/job:localhost/replica:0/task:0/cpu:0"](layer_conv1/bias)]]
So my question is, How can i solve this error?

Answer 1

This problem is caused by a bug in the 0.12rc0 release candidate of TensorFlow, and the fact that Pretty Tensor uses a deprecated TensorFlow API (for which I've opened an issue).
Until this bug is fixed, the best workaround I can think of is a hack. Add the following line at the top of your program, after import tensorflow as tf:
tf.GraphKeys.VARIABLES = tf.GraphKeys.GLOBAL_VARIABLES