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tf.keras.backend.is_keras_tensor

Returns whether x is a Keras tensor.

A "Keras tensor" is a tensor that was returned by a Keras layer, (Layer class) or by Input.

x A candidate tensor.

A boolean: Whether the argument is a Keras tensor.

ValueError In case x is not a symbolic tensor.

Examples:

np_var = np.array([1, 2])
# A numpy array is not a symbolic tensor.
tf.keras.backend.is_keras_tensor(np_var)
Traceback (most recent call last):

ValueError: Unexpectedly found an instance of type `<class 'numpy.ndarray'>`.
Expected a symbolic tensor instance.
keras_var = tf.keras.backend.variable(np_var)
# A variable created with the keras backend is not a Keras tensor.
tf.keras.backend.is_keras_tensor(keras_var)
False
keras_placeholder = tf.keras.backend.placeholder(shape=(2, 4, 5))
# A placeholder is a Keras tensor.
tf.keras.backend.is_keras_tensor(keras_placeholder)
True
keras_input = tf.keras.layers.Input([10])
# An Input is a Keras tensor.
tf.keras.backend.is_keras_tensor(keras_input)
True
keras_layer_output = tf.keras.layers.Dense(10)(keras_input)
# Any Keras layer output is a Keras tensor.
tf.keras.backend.is_keras_tensor(keras_layer_output)
True