ggforce

Accelarating ggplot2

About

ggforce is a package aimed at providing missing functionality to ggplot2 through the extension system introduced with ggplot2 v2.0.0. In general ggplot2 has been aimed primarily at ad hoc data visualization in order to investigate the data at hand, and less at utilities for composing custom plots a la D3.js. ggforce is mainly an attempt to address these "shortcomming" (design choices might be a better description). The long term goal is to have a repository of geoms, stats etc that are as well documented and implemented as the official ones found in ggplot2.

Disclaimer

The inclusion of any geom, stat, position etc in ggforce is not necessarily a recommendation of their use. ggplot2 has been succesfull in being opinionated about what functionality should be available. This is good as it insulates the user from making bad decisions when analyzing their data, but it also makes it difficult to develop novel visualizations using the ggplot2 API. ggforce on the other hand positions itself closer to the "anything goes - the user is responsible for the quality of the output". Despite this keep in mind that some things are always bad choices in data visualization: rainbow color scales, pie charts, overplotting etc. Don't do these things except with very good reasons.

Installation

Until more features are available the package will remain solemnly on Github. Once I believe it offers a large enough set of extensions it will be submitted to CRAN. Installation of ggforce is currently as follows:

if (!require(devtools)) {
    install.packages('devtools')
}
devtools::install_github('thomasp85/ggforce')

Current extensions

Following is a list of the functionality currently offered through ggforce

Geoms

• geom_arc: Drawing of circle segments
• geom_arc_bar: Drawing thick arcs and wedges
• geom_circle: Drawing circles with radius relative to coordinate scales
• geom_edge_bundle: Drawing of edge bundles from control points

Stats

• stat_arc: Companion to geom_arc
• stat_arc_bar: Generate arc/wedge polygons based on center, radius start

and end angle

• stat_pie: Generate arc/wedge polygons based on center, radius and value
• stat_circle: Generate circle polygon based on center and radius
• stat_edge_bundle: Generate coordinates based on control points for use

with geom_edge_bundle

Transformations

• power_trans: Create power transformations - somehow missing from scales
• trans_reverser: Reverse any transformation
• radial_trans: Transform between radial and cartesian coordinates

Themes

• theme_no_axes: A theme_bw() derived theme that removes axes and grids

from the plot

Pending extensions

• scale_direction for symbolizing segment/path/line direction using a

color/alpha gradient without occupying the color scale

• geom_spline for drawing xplines (low priority as already available through

ggalt)

• geom_d for drawing complex shapes in the manner of svg's d specification
• geom_chord for drawing chords (connections between circle segments)
• geom_bezier for drawing curves defined by start, end and two control points
• geom_pie_point for drawing scatterplots based on small pie charts
• geom_wordcloud for drawing wordclouds
• geom_axis for drawing axes in the plotting region
• geom_radial_axis as above but circular
• linear_trans for doing linear coordinate transformations (rotation, shearing,

reflection...)

• position_steam for drawing steamgraphs
• stat_arc_stacked for automatically calculating data for pie/donut charts
• stat_path_dir and stat_segment_dir for calculating path and segments

compatible with scale_direction

Contributions

Pull and feature requests are very welcome. Obviously PR's will lead to faster implementations than feature requests. I would like to urge requests to include the following if possible:

Pull requests

If a PR is for a new feature, it should be self contained, possibly using already implemented functionality if applicable. All exported functions should be documented following the style from ggplot2 using roxygen2 comment. You can credit yourself with the implementation in the documentation. If the feature concerns a visualization appraoch invented by others, please link to the article describing the approach.

Feature requests

If a feature is wished, but skill, time or other is lacking to create a full PR, please file an issue. The feature request should provide a detailed description of the nature of the feature, with links to relevant litterature describing the visualization type, as well as possible use cases to guide in designing the use cases.

Related projects

ggforce isn't nor should be the only package providing additional ggplot2 functionality. Following is a list in no particular order of kindred packages that I know of:

• ggplus: Based on pre-v2.0.0

ggplot2 some/most of this package might be unusable at this point. Only available on Github.

• ggalt: Similar in scope to ggforce.

Also available on CRAN

• ggfortify: Defines ggplot2

interfaces to common R packages using fortify and autoplot. Also available on CRAN

• ggrepel: Defines a

nifty geom_text_repel that forces text to move away from their origin to avoid overlaps. Available on CRAN

• ggtern: An extension for

creating terniary plots in ggplot2. Also available on CRAN