导入错误python

Question

在Python中，当我使用这个导入语句breze.learn.mlp import iter_minibatches时，会出现以下错误。

此处iter_minibatches是mlp.py中定义的函数。

Traceback (most recent call last):
  File "/home/vinod/PycharmProjects/MLPonTheano/MLPbreze.py", line 15, in <module>
    from breze.learn.mlp import Mlp, FastDropoutNetwork
  File "/home/vinod/breze/breze/learn/mlp.py", line 22, in <module>
    from breze.learn.base import SupervisedModel
  File "/home/vinod/breze/breze/learn/base.py", line 21, in <module>
    from breze.learn.mlp import iter_minibatches
ImportError: cannot import name iter_minibatches

Answer 1

你有一个循环导入; mlp导入base导入mlp：

# executing mlp.py
  File "/home/vinod/breze/breze/learn/mlp.py", line 22, in <module>
    from breze.learn.base import SupervisedModel
# executing base.py
  File "/home/vinod/breze/breze/learn/base.py", line 21, in <module>
# this tries to import from mlp again, but mlp isn't done yet
    from breze.learn.mlp import iter_minibatches

from breze.learn.base import SupervisedModel之后的任何行都不会被执行，因此导入这些行定义的任何对象都将失败。

避免循环导入，或者如果必须使用循环导入，则延迟导入其中一个模块以确保定义另一个模块中所需的对象。