包含了一些matplotlib的应用例子，包括了数据库连接的例子。是python数据处理学习的基础入门。部分代码附有注释。-Contains some matplotlib application examples, including examples of database connection. Basics of learning python data processing. Part of the code is annotated.

用Python画出一幅七色彩虹图的代码。(We draw a rainbow picture by Python.)