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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. |
Arguments |
x: A candidate tensor. |
Returns |
A boolean: Whether the argument is a Keras tensor. |
Raises |
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 |
get_uid function |
tf.keras.backend.get_uid(prefix="") |
Associates a string prefix with an integer counter in a TensorFlow graph. |
Arguments |
prefix: String prefix to index. |
Returns |
Unique integer ID. |
Example |
>>> get_uid('dense') |
1 |
>>> get_uid('dense') |
2 |
rnn function |
tf.keras.backend.rnn( |
step_function, |
inputs, |
initial_states, |
go_backwards=False, |
mask=None, |
constants=None, |
unroll=False, |
input_length=None, |
time_major=False, |
zero_output_for_mask=False, |
) |
Iterates over the time dimension of a tensor. |
Arguments |
step_function: RNN step function. Args; input; Tensor with shape (samples, ...) (no time dimension), representing input for the batch of samples at a certain time step. states; List of tensors. Returns; output; Tensor with shape (samples, output_dim) (no time dimension). new_states; List of tensors, same length and shapes as 'states'. The first state in the list must be the output tensor at the previous timestep. |
inputs: Tensor of temporal data of shape (samples, time, ...) (at least 3D), or nested tensors, and each of which has shape (samples, time, ...). |
initial_states: Tensor with shape (samples, state_size) (no time dimension), containing the initial values for the states used in the step function. In the case that state_size is in a nested shape, the shape of initial_states will also follow the nested structure. |
go_backwards: Boolean. If True, do the iteration over the time dimension in reverse order and return the reversed sequence. |
mask: Binary tensor with shape (samples, time, 1), with a zero for every element that is masked. |
constants: List of constant values passed at each step. |
unroll: Whether to unroll the RNN or to use a symbolic while_loop. |
input_length: An integer or a 1-D Tensor, depending on whether the time dimension is fixed-length or not. In case of variable length input, it is used for masking in case there's no mask specified. |
time_major: Boolean. If true, the inputs and outputs will be in shape (timesteps, batch, ...), whereas in the False case, it will be (batch, timesteps, ...). Using time_major = True is a bit more efficient because it avoids transposes at the beginning and end of the RNN calculation. However, most TensorFlow data is batch-major, so by default this function accepts input and emits output in batch-major form. |
zero_output_for_mask: Boolean. If True, the output for masked timestep will be zeros, whereas in the False case, output from previous timestep is returned. |
Returns |
A tuple, (last_output, outputs, new_states). last_output: the latest output of the rnn, of shape (samples, ...) outputs: tensor with shape (samples, time, ...) where each entry outputs[s, t] is the output of the step function at time t for sample s. new_states: list of tensors, latest states returned by the step function, of shape (samples, ...). |
Raises |
ValueError: if input dimension is less than 3. |
ValueError: if unroll is True but input timestep is not a fixed number. |
ValueError: if mask is provided (not None) but states is not provided (len(states) == 0). |
Model plotting utilities |
plot_model function |
tf.keras.utils.plot_model( |
model, |
to_file="model.png", |
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