由于版本兼容问题，Mac下Graphviz之前一直装的是低版本的2.36。高版本的安装方法如下：
1、log in & download Xcode an Xcode Command Line Tools from
install Xcode and the Xcode Command Line Tools
2、agree to Xcode license in terminal:
sudo xcodebuild –license
3、get MacPorts pkg installer for your version of osx from
install MacPorts for your version of osx
4、in terminal:
sudo port -v selfupdate
5、install graphviz via MacPorts. in terminal:
sudo port install graphviz-gui
installed gui application can be found here: /Application/Macports/Graphviz.app
相关MacPorts的命令说明可以看
我这里由于有之前的版本的 graphviz， 安装时候提示：
$ sudo port install graphviz-gui
---> Computing dependencies for graphviz-gui
---> Cleaning graphviz-gui
---> Scanning binaries for linking errors
Warning: Error parsing file /Applications/MacPorts/Graphviz.app/Contents/MacOS/Graphviz: Error opening or reading file
---> No broken files found.
解决方法：
先用 AppCleaner 清除之前的安装文件。
再用 sudo port uninstall graphviz-gui 卸载之前的安装依赖。
然后重新安装就可以安装成功了 2.40.1。
另外在做安装时，提示我要设置一些默认python 。 执行下面任何一个命令都可以完成。
---> Some of the ports you installed have notes:
python27 has the following notes:
To make this the default Python or Python 2 (i.e., the version run by the
'python' or 'python2' commands), run one or both of:
sudo port select --set python python27
sudo port select --set python2 python27
##############################################################
# IF YOU ARE USING PYTHON FROM THE TERMINAL, PLEASE INSTALL:
# py27-readline
# TO AVOID A LIBEDIT / PYTHON INTERACTION ISSUE.
# REF
##############################################################
这种方式安装完成后， GUI和命令行都是升级到了 2.40.1 版本了。
$ dot -V
dot - graphviz version 2.40.1 (20161225.0304)
