关于python2.7中matplotlib模块的安装

用easy-install安装matplotlib时报错：

                        * The following required packages can not be built:  
                        * freetype
error: Setup script exited with 1

那就安装freetye和png这两个库：

sudo apt-get install libfreetype6-dev
sudo apt-get install libpng12-dev

另外还需安装几个matplotlib依赖的几个模块：

sudo easy_install numpy
sudo easy_install tornado
sudo easy_install pyparsing