layers.py 文件源码

def gate_layer(tparams, X_word, X_char, options, prefix, pretrain_mode, activ='lambda x: x', **kwargs):
    """ 
    compute the forward pass for a gate layer

    Parameters
    ----------
    tparams        : OrderedDict of theano shared variables, {parameter name: value}
    X_word         : theano 3d tensor, word input, dimensions: (num of time steps, batch size, dim of vector)
    X_char         : theano 3d tensor, char input, dimensions: (num of time steps, batch size, dim of vector)
    options        : dictionary, {hyperparameter: value}
    prefix         : string, layer name
    pretrain_mode  : theano shared scalar, 0. = word only, 1. = char only, 2. = word & char
    activ          : string, activation function: 'liner', 'tanh', or 'rectifier'

    Returns
    -------
    X              : theano 3d tensor, final vector, dimensions: (num of time steps, batch size, dim of vector)

    """      
    # compute gating values, Eq.(3)
    G = tensor.nnet.sigmoid(tensor.dot(X_word, tparams[p_name(prefix, 'v')]) + tparams[p_name(prefix, 'b')][0])
    X = ifelse(tensor.le(pretrain_mode, numpy.float32(1.)),  
               ifelse(tensor.eq(pretrain_mode, numpy.float32(0.)), X_word, X_char),
               G[:, :, None] * X_char + (1. - G)[:, :, None] * X_word)   
    return eval(activ)(X)