Using R for photobiology

Package ‘ggpmisc’ focuses mainly on plot annotations. The new version fixes minor bugs and adds a major new feature: position functions for data aware nudging. These nudge functions were born out of an exchange of ideas with Kamil Slowikowski, the author and maintainer of the very popular package ‘ggrepel’. We are currently considering how to make them compatible with geom_text_repel() and geom_label_repel().

The package documentation web site at: https://docs.r4photobiology.info/ggpmisc/ now includes a changelog, so I am brief here.

Changes from version 0.3.8, the most recent CRAN release, are:

• Update the documentation of geom_plot().
• [Under development!] Link repositioned text to its original position with a segment or arrow: geom_linked_text(). Except for
  the drawing of segments or arrows this new geometry behaves as ggplot2::geom_text() . Note: Segments and arrows are drawn only
  if the position function used returns both the repositioned and original coordinates.
• Add support for advanced nudging: position_nudge_centre() and position_nudge_line() compute the direction of nudging and return
  both the nudged and original positions.
• Add support for simple nudging: position_nudge_to() nudges to new user-supplied position(s); position_nudge_keep() nudges to
  position(s) based on user-supplies position shift. These functions return both nudged and original position(s).

Example: Nudging text labels away from a curve.

library(ggpmisc)

set.seed(16532)
df <- data.frame(
  x = -10:10,
  y = (-10:10)^2 + rnorm(21, 0, 4),
  l = letters[1:21]
)

ggplot(df, aes(x, y, label = l)) +
  geom_point() +
  stat_smooth(method = "lm", formula = y ~ poly(x, 2, raw = TRUE)) +
  geom_text(aes(y = y, label = l),
            position = position_nudge_line(method = "lm",
                                           x = 0.4, 
                                           y = 4,
                                           formula = y ~ poly(x, 2, raw = TRUE),
                                           direction = "split"))

Roadmap: A split of the ‘ggpmisc’ package into two packages, one including the extensions to the grammar of graphics and another one including the functions related to plot annotations based on model fitting and statistical summaries seems necessary as the package has grown to include several extensions to the grammar of graphics that are generally useful. We are also working on improved inter-operation between ‘ggpmisc’ and ‘ggrepel’.

Acknowlegement: I thank Kamil Slowikowski for his contributions of ideas and for his willingness to keep the development of our packages coordinated. This update was done in part to address questions raised and reports of bugs by users, which I thank. The tag [ggpmisc] is in use at stackoverflow for questions related to the use this package. Please raise issues concerning bugs or enhancements to this package through GitHub at https://github.com/aphalo/ggpmisc/issues. Pull requests are also welcome.

Documentation web site at http://docs.r4photobiology.info/ggpmisc/ includes all help pages, with output from all examples, and vignettes in HTML format. The online vignettes include the output of all code examples, while the vignettes as included in the package, contain the output of only a subset of the code examples so as to keep the documentation at a reasonable size for package distribution.

NOTE: The new version of the package is on its way to CRAN.