tf.keras.layers.Bidirectional

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Class Bidirectional

Bidirectional wrapper for RNNs.

Inherits From: Wrapper

Aliases:

Arguments:

  • layer: Recurrent instance.
  • merge_mode: Mode by which outputs of the forward and backward RNNs will be combined. One of {'sum', 'mul', 'concat', 'ave', None}. If None, the outputs will not be combined, they will be returned as a list.
  • backward_layer: Optional Recurrent instance to be used to handle backwards input processing. If backward_layer is not provided, the layer instance passed as the layer argument will be used to generate the backward layer automatically. Note that the provided backward_layer layer should have properties matching those of the layer argument, in particular it should have the same values for stateful, return_states, return_sequence, etc. In addition, backward_layer and layer should have different go_backwards argument values. A ValueError will be raised if these requirements are not met.

Call arguments:

The call arguments for this layer are the same as those of the wrapped RNN layer.

Raises:

  • ValueError: 1. If layer or backward_layer is not a Layer instance.
    1. In case of invalid merge_mode argument.
    2. If backward_layer has mismatched properties compared to layer.

Examples:

model = Sequential()
model.add(Bidirectional(LSTM(10, return_sequences=True), input_shape=(5, 10)))
model.add(Bidirectional(LSTM(10)))
model.add(Dense(5))
model.add(Activation('softmax'))
model.compile(loss='categorical_crossentropy', optimizer='rmsprop')

 # With custom backward layer
 model = Sequential()
 forward_layer = LSTM(10, return_sequences=True)
 backard_layer = LSTM(10, activation='relu', return_sequences=True,
                      go_backwards=True)
 model.add(Bidirectional(forward_layer, backward_layer=backward_layer,
                         input_shape=(5, 10)))
 model.add(Dense(5))
 model.add(Activation('softmax'))
 model.compile(loss='categorical_crossentropy', optimizer='rmsprop')

__init__

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__init__(
    layer,
    merge_mode='concat',
    weights=None,
    backward_layer=None,
    **kwargs
)

Properties

constraints

Methods

tf.keras.layers.Bidirectional.reset_states

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reset_states()