`treemapify::geom_treemap()` support

[luisDVA]

Hi, As discussed on Twitter, just requesting support for pattern fill in treemaps created by treemapify::geom_treemap. I'll try to work on it myself and send a PR, but I'm not too confident about it. cheers

[BernhardClemm]

This would be a great feature to have!

[trevorld]

A user recently wrote in an email:

I recently wanted to apply patterns to geom_treemap() ... I am wondering whether this is on your agenda – and whether I could potentially help building this functionality ... Let me know whether my contribution could make sense, and if so how I could best get going (would probably need a short intro to the logic of the package).

• Adding new geoms like this one isn't on my agenda for #104

• A PR that adds support for this functionality would be welcome and I could help guide potential contributors through the process

• After the release of ggplot2 v3.5.0 there are two approaches to adding pattern support to a geom:

  • Update the original geom to support grid::pattern() / gradient fills (I opened an issue for this at https://github.com/wilkox/treemapify/issues/50)

    • Pros: Low amount of developer effort
    • Cons: Works in fewer graphics devices and versions of R, less ability to customize patterns in legends and with scales

  • Add a new geom based on the original geom to {ggpattern}

    • Pros: Works in more graphics devices and versions of R, more ability to customize patterns in legends and with scales
    • Cons: High amount of developer effort

• If you desire to add a new geom to {ggpattern} some notes:

  • One can use a good difftool like nvim -d to compare the geom files in {ggpattern} with those in {ggplot2}:

    • https://github.com/trevorld/ggpattern/pull/118 aims to reduce the visual differences between {ggpattern} and {ggplot2} 3.5 in such tools

  • We usually inherit the original Geom so we don't need to duplicate data setup code

  • We usually add some code to handle the new pattern aesthetics

  • We usually update the drawing code to instead of drawing one polygon/rect/path to instead

    • Draw the polygon/rect/path with fill and no border
    • Draw the patterns
    • Draw the polygon/rect/path with no fill and the col border

• You may need to copy and paste code from {treemapify} and/or ask them nicely to export more low-level functionality

  • Currently {ggpattern} is under the MIT license and {treemapify} is under the GPL-3 license. You may need to ask them nicely if you can copy the relevant code under the MIT license terms instead. They seemed willing to do this for the plotly team: https://github.com/wilkox/treemapify/issues/40 .

• If importing code from {treemapify} please put the package in the Suggests instead of Imports field of our DESCRIPTION

[trevorld]

• Pattern fills (such as those returned by gridpattern::patternFill()) should now work in the development version of {treemapify}: https://github.com/wilkox/treemapify/commit/082641ae9acd1461a59066dd2a1ec833be7c2d72
• We'll keep this issue open in case someone would like to add a PR for a geom_treemap_pattern()