Plots as a guide

[teunbrand]

Taking this one step further, do you think legendry could accommodate completely arbitrary plots as shown here? My naive understanding is that this could be a new type of guide which accepts a function that produces a plot and receives the limits. For axis guides, one would need to ensure that the output is correctly aligned, and for legend guides one would need to think through how to do the layouting.

Originally posted by @const-ae in #38 (comment)

[teunbrand]

This feature would require tidyverse/ggplot2#3441 to be completed in order to copy the scale from one plot to the next.

[aphalo]

I think this feature would be useful also when plotting light spectra for adding a graphical guide showing the colours matching the different wavelengths. In 'ggspectra' I am faking this with a geom call, but it depends on the manual fill scale which is undesirable in many cases. Even if a better approach with geoms would be possible, semantically it functions as a guide.

[teunbrand]

Yeah if your axis is wavelength, it'd make sense to align a visual spectrum along that axis. I probably won't implement something as specific as a wavelength axis, but I'd like to make it easier to build your own.