【读书笔记】The Grammar of Graphics - 8. Geometry

8. 几何对象Geometry

Grometric graphs are not visible. As Bertin(1967, 1977) points out, visible elements have features not present in their geometric counterparts.

图形语法中的graph的概念是一个相对抽象的数学概念,其并不对应任何可见的图形,可见的图形是在graph的基础上关联视觉元素(颜色、大小等信息)。

Graph != Physical Representation

对图形分类的方法

  1. appearance under standard aesthetic functions(反例,line != path,但视觉表现相同)
  2. classify them by their geimetric dimensionality
  3. organize them by thier data methods

文章最后采用了根据数据和几何特征来划分几何对象,原因是本文讨论的是基于统计的几何系统,所以要

based on how graphs function in representing statistical data geometrically.

  • Functions 映射数据
  • Partitions 类似于一种分组操作(拆分成子集)
  • networks 连接操作,如line()
Functions Partitions Networks
point
line
area
interval
path
schema
polygon
contour
edge

Collision Modifiers (碰撞调整器)

碰撞调整器用于调整在图形绘制的时候出现的图形位置冲突覆盖的问题。

  • Slack: symmetric, asymmetric(堆叠图的调整方法)
  • Dodge: symmetric, asymmetric (分组图的调整方法,把覆盖的图形偏移一定的位置)
  • jitter: uniform, normal (随机偏移)

一般对于散点图,超过5000个点时性能可能出现问题,这时建议对数据进行聚合或者使用概率分布之类的方法来绘制图形。

Author: Lobay Kanna
Link: http://lobay.moe/2019/03/28/GoG/8. 几何对象Geometry/
Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 4.0 unless stating additionally.