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ORGANISING INFORMATION


Each glyph representing a case is its own data structure, or object, called a point-symbol; similarly there is an axis object, and a label object. Even though a scatterplot is composed of point symbols, axes and a few labels, it is convenient to introduce an intermediate object called a 2d-pointcloud object consisting of the point symbols. In general then, a statistical plot is a hierarchy of objects; the scatterplot object consists of axes, label and a point cloud which itself consists of point symbols, while a scatterplot matrix consists of many point clouds and labels.

The plot and each of its components are termed a view. A simple view is a view such as a point symbol or label which contains no other views. All other views are referred to as compound views. In our software organisation, information pertaining to a particular view is localised in that view. All views have the slots summarised in the following table:

Slot Purpose Example
Viewed object The data structure being `viewed' scatterplot: dataset
    point symbol: case
    function-view: single variable function
Drawing style Controls appearance colour, highlighting
Viewports Screen locations where view appears  
Menus User interface to view Change colour, variate
    Access viewed object
A compound view also has slots for its constituent views or subviews and the subview locations. Note that these are not the same as the viewport locations: compound views position subviews using some abstract coordinate system which is meaningful for that compound view. When a compound view is first drawn in a viewport, the subview locations are used to determine viewports for the subviews.


next up previous
Next: ORGANISING INFORMATION GRAPHICALLY Up: No Title Previous: INTRODUCTION

2000-01-28