在 {'theano', 'tensorflow'} AssertionError 中断言 _backend

Question

我正在尝试运行 this code，但出现以下错误：

Traceback (most recent call last):
  File "classifier_from_little_data_script_3.py", line 39, in <module>
    from keras import applications
  File "C:\Python35\lib\site-packages\keras\__init__.py", line 3, in <module>
    from . import activations
  File "C:\Python35\lib\site-packages\keras\activations.py", line 3, in <module>
    from . import backend as K
  File "C:\Python35\lib\site-packages\keras\backend\__init__.py", line 36, in <module>
    assert _backend in {'theano', 'tensorflow'}
AssertionError

我试图寻找此错误的原因，但找不到解决方案。我该如何解决这个问题？

编辑 1

这是 keras.json 文件：

{
    "image_dim_ordering": "tf",
    "epsilon": 1e-07,
    "floatx": "float32",
    "backend": "tf"
}

编辑 2

我已将后端更改为 tensorflow，但出现以下错误：

ValueError: The shape of the input to "Flatten" is not fully defined (got (None, None, 512). Make sure to pass a complete "input_shape" or "batch_input_shape" argument to the first layer in your model.

我为第二次编辑添加了一个单独的问题，here。

谢谢。

Answer 1

你的 keras.json 应该是这样的

{
    "image_data_format": "channels_last",
    "epsilon": 1e-07,
    "floatx": "float32",
    "backend": "tensorflow" 
}

注意 "backend" : "tensorflow" 与您所拥有的 "backend" : "tf"

的区别

在 {'theano', 'tensorflow'} AssertionError 中断言 _backend

assert _backend in {'theano', 'tensorflow'} AssertionError

python

theano

keras

tensorflow