convolution.py 文件源码

def temporal_padding_mask(mask, kernel_size, padding_size):
    """Pad the middle dimension of a 2D matrix
    with "padding" zeros left and right.

    Apologies for the inane API, but Theano makes this
    really hard.
    Code from https://github.com/fchollet/keras/blob/master/keras/backend/theano_backend.py
    x: (batch, length)
    """
    mask_shape = mask.shape
    mask_sum = T.sum(mask, axis=1)
    output_length = mask_sum - kernel_size + 2 * padding_size + 1
    max_output_length = mask_shape[1] - kernel_size + 2 * padding_size + 1
    real_output_length = T.maximum(output_length, 1)
    range_base = T.arange(max_output_length)
    range_matrix = T.outer(T.ones((mask_shape[0],)), range_base)
    mask = (range_matrix < real_output_length[:, None]) * T.constant(1.0)
    return mask