Facet Wraps in ggplot2: Mastering '~' and '.' for Customized Faceting Schemes

Faceting Gauge Charts in ggplot2: How to Fix Incorrect Titles and Subtitles in the First Facet Panel

Faceting Text on Individual Panels in ggplot2: A Customizable Annotation Solution

Customizing Data Formats in Different Facets of a ggplot2 Plot