CS 20 : TensorFlow for Deep Learning Research¶

Lecture 01 : Overview of Tensorflow¶

Setup¶

In [1]:

from __future__ import absolute_import, division, print_function
import numpy as np
import tensorflow as tf

print(tf.__version__)
sess_config = tf.ConfigProto(gpu_options=tf.GPUOptions(allow_growth=True))

1.12.0

In [2]:

a = tf.add(3, 5)
print(a)

Tensor("Add:0", shape=(), dtype=int32)

In [3]:

sess = tf.Session(config = sess_config)
print(sess.run(a))
sess.close()

In [4]:

with tf.Session(config = sess_config) as sess:
    print(a)
    print(sess.run(a))

Tensor("Add:0", shape=(), dtype=int32)
8

In [5]:

print(tf.get_default_graph().get_operations())

[<tf.Operation 'Add/x' type=Const>, <tf.Operation 'Add/y' type=Const>, <tf.Operation 'Add' type=Add>]

In [6]:

tf.reset_default_graph()

x, y = 2, 3
add_op = tf.add(x,y)
mul_op = tf.multiply(x,y)
useless = tf.multiply(x, add_op)
pow_op = tf.pow(add_op, mul_op)
with tf.Session(config = sess_config) as sess:
    z, not_useless = sess.run([pow_op, useless])
print(z, not_useless)

15625 10

In [7]:

print(tf.get_default_graph().get_operations())

[<tf.Operation 'Add/x' type=Const>, <tf.Operation 'Add/y' type=Const>, <tf.Operation 'Add' type=Add>, <tf.Operation 'Mul/x' type=Const>, <tf.Operation 'Mul/y' type=Const>, <tf.Operation 'Mul' type=Mul>, <tf.Operation 'Mul_1/x' type=Const>, <tf.Operation 'Mul_1' type=Mul>, <tf.Operation 'Pow' type=Pow>]

In [8]:

tf.reset_default_graph()

g = tf.Graph()
with g.as_default():
    x = tf.add(3,5)
with tf.Session(config = sess_config) as sess: # graph argument is none -> launch default graph
    print(sess.run(x))

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-8-3cb1b3c3e0e6> in <module>
      5     x = tf.add(3,5)
      6 with tf.Session(config = sess_config) as sess: # graph argument is none -> launch default graph
----> 7     print(sess.run(x))

/usr/local/var/pyenv/versions/3.6.6/envs/tensorflow/lib/python3.6/site-packages/tensorflow/python/client/session.py in run(self, fetches, feed_dict, options, run_metadata)
    927     try:
    928       result = self._run(None, fetches, feed_dict, options_ptr,
--> 929                          run_metadata_ptr)
    930       if run_metadata:
    931         proto_data = tf_session.TF_GetBuffer(run_metadata_ptr)

/usr/local/var/pyenv/versions/3.6.6/envs/tensorflow/lib/python3.6/site-packages/tensorflow/python/client/session.py in _run(self, handle, fetches, feed_dict, options, run_metadata)
   1075       raise RuntimeError('Attempted to use a closed Session.')
   1076     if self.graph.version == 0:
-> 1077       raise RuntimeError('The Session graph is empty.  Add operations to the '
   1078                          'graph before calling run().')
   1079 

RuntimeError: The Session graph is empty.  Add operations to the graph before calling run().

In [9]:

print(g.get_operations())

[<tf.Operation 'Add/x' type=Const>, <tf.Operation 'Add/y' type=Const>, <tf.Operation 'Add' type=Add>]

In [10]:

print(tf.get_default_graph().get_operations())

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