LSTM cell layer

[source]

LSTMCell class

keras.layers.LSTMCell(
    units,
    activation="tanh",
    recurrent_activation="sigmoid",
    use_bias=True,
    kernel_initializer="glorot_uniform",
    recurrent_initializer="orthogonal",
    bias_initializer="zeros",
    unit_forget_bias=True,
    kernel_regularizer=None,
    recurrent_regularizer=None,
    bias_regularizer=None,
    kernel_constraint=None,
    recurrent_constraint=None,
    bias_constraint=None,
    dropout=0.0,
    recurrent_dropout=0.0,
    seed=None,
    **kwargs
)

Cell class for the LSTM layer.

This class processes one step within the whole time sequence input, whereas keras.layer.LSTM processes the whole sequence.

Arguments

• units: Positive integer, dimensionality of the output space.
• activation: Activation function to use. Default: hyperbolic tangent (tanh). If you pass None, no activation is applied (ie. "linear" activation: a(x) = x).
• recurrent_activation: Activation function to use for the recurrent step. Default: sigmoid (sigmoid). If you pass None, no activation is applied (ie. "linear" activation: a(x) = x).
• use_bias: Boolean, (default True), whether the layer should use a bias vector.
• kernel_initializer: Initializer for the kernel weights matrix, used for the linear transformation of the inputs. Default: "glorot_uniform".
• recurrent_initializer: Initializer for the recurrent_kernel weights matrix, used for the linear transformation of the recurrent state. Default: "orthogonal".
• bias_initializer: Initializer for the bias vector. Default: "zeros".
• unit_forget_bias: Boolean (default True). If True, add 1 to the bias of the forget gate at initialization. Setting it to True will also force bias_initializer="zeros". This is recommended in Jozefowicz et al.
• kernel_regularizer: Regularizer function applied to the kernel weights matrix. Default: None.
• recurrent_regularizer: Regularizer function applied to the recurrent_kernel weights matrix. Default: None.
• bias_regularizer: Regularizer function applied to the bias vector. Default: None.
• kernel_constraint: Constraint function applied to the kernel weights matrix. Default: None.
• recurrent_constraint: Constraint function applied to the recurrent_kernel weights matrix. Default: None.
• bias_constraint: Constraint function applied to the bias vector. Default: None.
• dropout: Float between 0 and 1. Fraction of the units to drop for the linear transformation of the inputs. Default: 0.
• recurrent_dropout: Float between 0 and 1. Fraction of the units to drop for the linear transformation of the recurrent state. Default: 0.
• seed: Random seed for dropout.

Call arguments

• inputs: A 2D tensor, with shape (batch, features).
• states: A 2D tensor with shape (batch, units), which is the state from the previous time step.
• training: Python boolean indicating whether the layer should behave in training mode or in inference mode. Only relevant when dropout or recurrent_dropout is used.

Example

>>> inputs = np.random.random((32, 10, 8))
>>> rnn = keras.layers.RNN(keras.layers.LSTMCell(4))
>>> output = rnn(inputs)
>>> output.shape
(32, 4)
>>> rnn = keras.layers.RNN(
...    keras.layers.LSTMCell(4),
...    return_sequences=True,
...    return_state=True)
>>> whole_sequence_output, final_state = rnn(inputs)
>>> whole_sequence_output.shape
(32, 10, 4)
>>> final_state.shape
(32, 4)