tf.keras.backend.is_keras_tensor

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Returns whether x is a Keras tensor.

tf.keras.backend.is_keras_tensor(
    x
)

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:

    import tensorflow as tf
    import numpy
    from keras import backend as K
    from keras.layers import Input, Dense
    np_var = numpy.array([1, 2])
    K.is_keras_tensor(np_var) # A numpy array is not a symbolic tensor.
        ValueError
    k_var = tf.compat.v1.placeholder('float32', shape=(1,1))
    K.is_keras_tensor(k_var) # A variable indirectly created outside of
        keras is not a Keras tensor.
        False
    keras_var = K.variable(np_var)
    K.is_keras_tensor(keras_var)  # A variable created with the keras
        backend is not a Keras tensor.
        False
    keras_placeholder = K.placeholder(shape=(2, 4, 5))
    K.is_keras_tensor(keras_placeholder)  # A placeholder is not a Keras
        tensor.
        False
    keras_input = Input([10])
    K.is_keras_tensor(keras_input) # An Input is a Keras tensor.
        True
    keras_layer_output = Dense(10)(keras_input)
    K.is_keras_tensor(keras_layer_output) # Any Keras layer output is a
        Keras tensor.
        True