class tf.contrib.rnn.BasicLSTMCell

class tf.contrib.rnn.core_rnn_cell.BasicLSTMCell

See the guide: RNN and Cells (contrib) > Core RNN Cells for use with TensorFlow's core RNN methods

Basic LSTM recurrent network cell.

The implementation is based on:

We add forget_bias (default: 1) to the biases of the forget gate in order to reduce the scale of forgetting in the beginning of the training.

It does not allow cell clipping, a projection layer, and does not use peep-hole connections: it is the basic baseline.

For advanced models, please use the full LSTMCell that follows.





__init__(num_units, forget_bias=1.0, input_size=None, state_is_tuple=True, activation=tf.tanh)

Initialize the basic LSTM cell.


  • num_units: int, The number of units in the LSTM cell.
  • forget_bias: float, The bias added to forget gates (see above).
  • input_size: Deprecated and unused.
  • state_is_tuple: If True, accepted and returned states are 2-tuples of the c_state and m_state. If False, they are concatenated along the column axis. The latter behavior will soon be deprecated.
  • activation: Activation function of the inner states.

zero_state(batch_size, dtype)

Return zero-filled state tensor(s).


  • batch_size: int, float, or unit Tensor representing the batch size.
  • dtype: the data type to use for the state.


If state_size is an int or TensorShape, then the return value is a N-D tensor of shape [batch_size x state_size] filled with zeros.

If state_size is a nested list or tuple, then the return value is a nested list or tuple (of the same structure) of 2-D tensors with the shapes [batch_size x s] for each s in state_size.

Defined in tensorflow/contrib/rnn/python/ops/