奠基性的思想与表达

引言

- Grammar / graph

- 词源：前者 from gramma, grammat- ‘letter of the alphabet, thing written’；后者 from Greek graphē ‘writing’，衍生出了前者 - Graphics是可被感知（perceivable）的graph

- Graphics / Charts

This book SHUNs chart typologies.

- 语法上的差异是更本质的：饼图是条形图的一种（a pie is a divided bar in polar coordinates），而直方图（histogram）并不是。 - 为了代码的简洁，应考虑graphics的共同逻辑，而不是若干种看似不同的charts的。

- Object-Oriented Design

- 特点 - 对象可以复用。 - 模块化。 - 当一类对象（class or category）看起来合用的时候，应该考虑是否有更general的类型，使得前者是后者的一个实例（instance）。 - 注意 - OOD并不是一种编程语言，而且面向对象的语言（如Java）也并不一定意味着程序是OOD的。 - OOD也不是GUI或交互系统。

- OOD is a natural framework for thinking about graphics because graphics ARE objects (Hurley and Oldford, 1991)

- Object-Oriented Graphics Design

- 规范（Specification） - Frame: Cross Dimension_A with Dimension_B to produce a two-dimensional graph - Graph: line (eg. contour), dot, ... - Guide: axis, tick, label, ... - 组合（Assembly） - Inheritance: Tasks relating to guiding, such as relating numeric values to text strings, can be implemented in one Guide class. （enable them to represent themselves in a frame.） - Aggregation: A chart has a Frame, one or more Guides, and one or more Graphs. - 呈现（Display） - Add a graphic to a frame/Remove/Transform/Permute/... WITHOUT redefining the basic structure.

Unless one specifies those rules explicitly, one cannot begin to claim that a particular graphic is meaningless or not. ...

Most data mining systems still rely on pie, line, and bar charts of slices of data cubes (multi-way aggregations of a subset of a database). These charts fail to reveal the relationships among the entities they represent because they have NO deep grammar for generating them.

举例：如何绘制一个饼图

-tbc-