Slides and notes for an discussion presentation to the ggextenders group (XX February 2025).

There are many visual idioms in place for plotting time series data, however little work has been done to express them as elements of a unified grammar of temporal graphics. The ggtime package extends ggplot2 with new grammatical elements for presenting temporal patterns. These elements can be composed together to create familiar visual idioms, and also recombined in new ways to create new informative plots. Temporal visualisation requires special handling to accomodate calendrical quirks (similar to spatial, graph, and uncertainty visualisation). In this ggextenders talk I will introduce some design-stage development of the ggtime package, and pose some technical discussion questions about engineering and designing ggplot2 extensions.

• Background (time as a special dimension, relate mixtime/ggtime to distributional/ggdist)

• Existing work producing visual idioms (feasts, sugrrants, gravitas)

• Design philosophy: use grammar layers to extend time independently of other layers (ggtime ❤️ ggdist)

• Design decision discussions

  Start with the question prompt, along with some related work and necessary info.

  • Design decision 1: implementation of coord_calender()
  • Design decision 2: geom_time_line() or position_civil()/position_absolute() for civil/absolute time
  • Design decision 3: circular time as a position? data pre-processing

1 hour total (including discussion)