keras框架下使用Graphviz报错（jupyter环境）

keras框架下使用Graphviz报错（jupyter环境）

安装pydot与Graphviz方法

• 打开Anaconda Prompt
• pip install pydot
• pip install graphviz
• 官网下载Graphviz：https://www.graphviz.org/download/ ，下载后安装，并将安装路径（如E:\Program Files (x86)\Graphviz2.38\bin）加入环境变量PATH中

问题再现

在jupyter中调用

plot_model(happyModel, to_file='HappyModel.png')
SVG(model_to_dot(happyModel).create(prog='dot', format='svg'))

运行错误，显示错误信息为：

During handling of the above exception, another exception occurred:

OSError                                   Traceback (most recent call last)
<ipython-input-16-94e567feb269> in <module>
----> 1 plot_model(happyModel, to_file='HappyModel.png')
      2 SVG(model_to_dot(happyModel).create(prog='dot', format='svg'))

D:\Anaconda3\lib\site-packages\keras\utils\vis_utils.py in plot_model(model, to_file, show_shapes, show_layer_names, rankdir)
    132             'LR' creates a horizontal plot.
    133     """
--> 134     dot = model_to_dot(model, show_shapes, show_layer_names, rankdir)
    135     _, extension = os.path.splitext(to_file)
    136     if not extension:

D:\Anaconda3\lib\site-packages\keras\utils\vis_utils.py in model_to_dot(model, show_shapes, show_layer_names, rankdir)
     55     from ..models import Sequential
     56 
---> 57     _check_pydot()
     58     dot = pydot.Dot()
     59     dot.set('rankdir', rankdir)

D:\Anaconda3\lib\site-packages\keras\utils\vis_utils.py in _check_pydot()
     29     except OSError:
     30         raise OSError(
---> 31             '`pydot` failed to call GraphViz.'
     32             'Please install GraphViz (https://www.graphviz.org/) '
     33             'and ensure that its executables are in the $PATH.')

OSError: `pydot` failed to call GraphViz.Please install GraphViz (https://www.graphviz.org/) and ensure that its executables are in the $PATH.

但是Graphviz已经正确安装，并且环境变量也已配置正确。

原因分析

在Anaconda安装目录keras包中的…\Anaconda3\Lib\site-packages\keras\utils\vis_utils.py文件中有：

# `pydot` is an optional dependency,
# see `extras_require` in `setup.py`.
try:
    import pydot
except ImportError:
    pydot = None

def _check_pydot():