Effective visualization with {ggplot2} and R

2024-09-05

1 Where to start?

  • Know your goal
  • Know your audience
  • Know your format

2 What next?

  • Choosing appropriate graphic types
  • Writing and formatting clear text
  • Selecting appropriate and engaging colors
  • Preparing your feature geometry appropriately

3 Choosing appropriate graphic types

  • What makes one graphic, chart, plot, or map “better” or “worse”?

What makes a bad map bad?

For new map makers who might not know any better, it is often:

  • Confusing or distracting layout
  • Not enough color contrast for features
  • Cluttered labels, legends, or features

What makes a fine map just fine?

For more experienced map makers who might be in a hurry:

  • Not enough thought on font sizes and styling
  • No feature generalization (simplifying geometry where appropriate for the map scale or subject)
  • Inappropriate color scales

There are many cartographic considerations that also apply to other all types of data visualization:

  • Layout
  • Fonts (Typography)
  • Colors
  • Output formats

But there are also some cartographic considerations that apply to maps in special and important ways:

  • Feature geometry (and cartographic conventions)
  • Projections
  • Scaling

4 Items, Attributes, Marks, and Channels

In Visualization Analysis and Design (2014), Tamara Munzner describes a set of useful concepts:

  • items,
  • attributes,
  • links,
  • marks,
  • and channels

5 Items and Attributes

Items

basic units on which data is collected

Attributes

numerical or categorical features of the data items we want to represent

Links

relations among items, e.g. months within a year, or countries within a continent.

6 Marks and Channels

Marks

geometric entities used to represent items: points, lines, areas.

Visual channels

features of marks that can be used to reflect values of attributes.”