How can you get length of a TensorFlow string?

Question

Is there any way to get length of a TensorFlow string within TensorFlow? For example, is there any function that returns the length of a = tf.constant("Hello everyone", tf.string) as 14 without passing the string back to Python.

Answer 1

This works for me:

x = tf.constant("Hello everyone")

# Launch the default graph.
with tf.Session() as sess:
    print(tf.size(tf.string_split([x],"")).eval())

Answer 2

No such function exists as of TensorFlow version 0.9. However, you can use tf.py_func to run arbitrary Python functions over TensorFlow tensors. Here is one way to get length of a TensorFlow string :

def string_length(t):
  return tf.py_func(lambda p: [len(x) for x in p], [t], [tf.int64])[0]

a = tf.constant(["Hello everyone"], tf.string)
sess = tf.InteractiveSession()
sess.run(string_length(a))