python - How do I get the current value of a Variable?

Question

Suppose we have a variable:

x = tf.Variable(...)

This variable can be updated during the training process using the assign() method.

What is the best way to get the current value of a variable?

I know we could use this:

session.run(x)

But I'm afraid this would trigger a whole chain of operations.

In Theano, you could just do

y = theano.shared(...)
y_vals = y.get_value()

I'm looking for the equivalent thing in TensorFlow.

Answer 1

The only way to get the value of the variable is by running it in a session. In the FAQ it is written that:

A Tensor object is a symbolic handle to the result of an operation, but does not actually hold the values of the operation's output.

So TF equivalent would be:

import tensorflow as tf

x = tf.Variable([1.0, 2.0])

init = tf.global_variables_initializer()

with tf.Session() as sess:
    sess.run(init)
    v = sess.run(x)
    print(v)  # will show you your variable.

The part with init = global_variables_initializer() is important and should be done in order to initialize variables.

Also, take a look at InteractiveSession if you work in IPython.