python - 在运行时获取HybridBlock图层形状

我正在尝试构建自定义池层（用于ndarray和Symbol），并且我需要在运行时知道输入形状。根据文档，HybridBlock具有功能“ infer_shape”，但我无法使其正常工作。任何指示我做错了什么？

mxnet版本

1.0.0，从conda，python3构建。

最小可复制示例

例如：

import mxnet as mx
import mxnet.ndarray as nd
from mxnet.gluon import HybridBlock

class runtime_shape(HybridBlock):


    def __init__(self,  **kwards):
        HybridBlock.__init__(self,**kwards)


    def hybrid_forward(self,F,_input):

        print (self.infer_shape(_input))

        return _input

xx = nd.random_uniform(shape=[5,5,16,16])

mynet = runtime_shape()
mynet.hybrid_forward(nd,xx)

错误信息：

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-41-3f539a940958> in <module>()
----> 1 mynet.hybrid_forward(nd,xx)

<ipython-input-38-afc9785b716d> in hybrid_forward(self, F, _input)
     17     def hybrid_forward(self,F,_input):
     18
---> 19         print (self.infer_shape(_input))
     20
     21         return _input

 /home/dia021/anaconda2/lib/python2.7/site-packages/mxnet/gluon/block.pyc in infer_shape(self, *args)
    460     def infer_shape(self, *args):
    461         """Infers shape of Parameters from inputs."""
--> 462         self._infer_attrs('infer_shape', 'shape', *args)
    463
    464     def infer_type(self, *args):

/home/dia021/anaconda2/lib/python2.7/site-packages/mxnet/gluon/block.pyc in _infer_attrs(self, infer_fn, attr, *args)
    448     def _infer_attrs(self, infer_fn, attr, *args):
    449         """Generic infer attributes."""
--> 450         inputs, out = self._get_graph(*args)
    451         args, _ = _flatten(args)
    452         arg_attrs, _, aux_attrs = getattr(out, infer_fn)(

/home/dia021/anaconda2/lib/python2.7/site-packages/mxnet/gluon/block.pyc in _get_graph(self, *args)
    369             params = {i: j.var() for i, j in self._reg_params.items()}
    370             with self.name_scope():
--> 371                 out = self.hybrid_forward(symbol, *grouped_inputs, **params)  # pylint: disable=no-value-for-parameter
    372             out, self._out_format = _flatten(out)
    373

/home/dia021/anaconda2/lib/python2.7/site-packages/mxnet/gluon/block.pyc in __exit__(self, ptype, value, trace)
     78         if self._block._empty_prefix:
     79             return
---> 80         self._name_scope.__exit__(ptype, value, trace)
     81         self._name_scope = None
     82         _BlockScope._current = self._old_scope

AttributeError: 'NoneType' object has no attribute '__exit__'

最佳答案

HybridBlock的想法是使在命令式环境中的调试变得容易，您可以在其中简单地放置一个断点或print语句，并查看哪些数据流过您的网络。当您确信网络正在执行您想要的操作时，您可以致电.hybridize()享受速度的提高。

在开发网络并使用命令式模式时，您可以简单地打印：
print('shape',_input.shape)

并在使用网络的混合版本时删除此行，因为这仅适用于NDArrays。

如果这不能回答您的问题，您能否精确确定通过获取输入数据的形状要达到的目标？