在用Python學習構建決策樹是，需要視覺化已構建好的決策樹，需要用到pydotplus包，那面如何在anaconda中安裝呢？

使用如下程式碼：

conda install -c conda-forge pydotplus

http://stackoverflow.com/questions/36979421/how-can-i-use-conda-to-install-pydotplus/40719179

此時，如果未安裝graphviz，程式還是會報錯的

graphviz下載地址：

http://www.graphviz.org/Download_windows.php

處理過程：

The problem is that the path to GraphViz was not found by the pydot module as shown in the traceback:

'GraphViz\'s executables not found'

I solved this problem on my windows 7 machine by adding the GraphViz bin directory to my computer's PATH. Then restarting my python IDE to use the updated path.

1. Install GraphViz if you haven't already (I used the MSI download)
2. Get the path for gvedit.exe (for me it was "C:\Program Files (x86)\Graphviz2.34\bin\")
3. Add this path to the computer's PATH
4. One way to get to environment settings to set your path is to click on each of these button/menu options: start->computer->system properties->advanced settings->environment variables
5. Click Edit User path
6. Add this string to the end of your Variable value list (including semicolon): ;C:\Program Files (x86)\Graphviz2.34\bin
7. Click OK
8. Restart your Python IDE