colorplaner: ggplot2 Extension to Visualize Two Variables Per Color Aesthetic through Color Space Projection

Description

Add additional dimensionality to visualizations by using the color and/or fill aesthetics to convey the values of two continuous variables each. By projecting variable values onto YUV color space, a scale is created that allows viewers to intuitively determine the values of both variables from the single displayed color. Includes two new scales and a new guide for ggplot2. See scale_color_colorplane for usage.

Requirement for Package Attachment

At present, guide_colorplane will only function when the colorplaner package is attached to the search list. For scripting or interactive use, use library(colorplaner). For package development, add colorplaner to the Depends list in your DESCRIPTION file.

This requirement exists because ggplot2 guides function through the use of S3 generics and methods, but the generic functions are not exported from the ggplot package. Without access to the generics, the methods for the colorplane guide cannot be properly registered and will only be found by the dispatcher if in the search path.

Check https://github.com/wmurphyrd/colorplaner/issues/27 for current status and progress towards resolving this issue.

Warning Message About Ignoring Unknown Aesthetics

Layers now produce a warning message when unrecognized aesthetics are found but have no mechanism for notifying them of aesthetics handled by scales. The warning can be avoided by mapping color2/fill2 at the plot level (i.e. in the initial ggplot() statement). If you want to avoid colorplane mapping on all layers, map color/fill only on the layers you want, as in the example below.

Examples

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library(ggplot2)
ggplot(iris, aes(x = Sepal.Length, y = Sepal.Width,
  colour2 = Petal.Width)) +
 geom_point(aes(colour = Petal.Length)) +
 geom_line(aes(linetype = Species)) +
 scale_color_colorplane()