TensorFlow 1 version View source on GitHub

Asserts that the given condition is true.

    condition, data, summarize=None, name=None

If condition evaluates to false, print the list of tensors in data. summarize determines how many entries of the tensors to print.

NOTE: In graph mode, to ensure that Assert executes, one usually attaches a dependency:

# Ensure maximum element of x is smaller or equal to 1
assert_op = tf.Assert(tf.less_equal(tf.reduce_max(x), 1.), [x])
with tf.control_dependencies([assert_op]):
  ... code using x ...


  • condition: The condition to evaluate.
  • data: The tensors to print out when condition is false.
  • summarize: Print this many entries of each tensor.
  • name: A name for this operation (optional).



NOTE The output of this function should be used. If it is not, a warning will be logged or an error may be raised. To mark the output as used, call its .mark_used() method.

Eager Compatibility

tf.errors.InvalidArgumentError if condition is not true