layers.py 文件源码

def pad_to_size(bottom, output_size):

    ''' 
    A layer used to pad the tensor bottom to output_size by padding zeros around it
    TODO: implement for 3D data
    '''

    input_size = bottom.get_shape().as_list()
    size_diff = np.subtract(output_size, input_size)

    pad_size = size_diff // 2
    odd_bit = np.mod(size_diff, 2)

    if len(input_size) == 4:

        padded =  tf.pad(bottom, paddings=[[0,0],
                                        [pad_size[1], pad_size[1] + odd_bit[1]],
                                        [pad_size[2], pad_size[2] + odd_bit[2]],
                                        [0,0]])

        return padded

    elif len(input_size) == 5:
        raise NotImplementedError('This layer has not yet been extended to 3D')
    else:
        raise ValueError('Unexpected input size: %d' % input_size)