代码：

from theano.tensor.signal import downsample
pooled_out = downsample.max_pool_2d(
       input=conv_out,
       ds=poolsize,
       ignore_border=True
)

错误：

ImportError: cannot import name 'downsample' from 'theano.tensor.signal'

原因：

theano库的接口变更

解决办法：

from theano.tensor.signal import pool
pooled_out = pool.pool_2d(
     input=conv_out,
     ws=poolsize,
     ignore_border=True
)