Adding pattern aesthetic to ggalluvial plot

[AliceL90]

Hi, Thanks a lot for creating this package, it is beautiful! I was wondering if it could be possible to add a feature to the ggalluvial plot. Maybe it is already possible, but I did not manage to do it.

I would like to add pattern to the stratum of interest. I tried to use the aesthetic pattern from ggpattern, but I saw that pattern is not an aestethic accepted by geom_alluvium or geom_stratum.

Is it something that would be possible or of interest to add to the package? I find it can help focusing on specific strata when the plot are a bit busy. Here is an example of what I would like to achieve, using the vaccinations dataset. I have added a pattern with Power Point on the 'Missing' group.

[corybrunson]

Hi @AliceL90, thanks a lot for raising this issue. It's something i'd love to be able to do.

A while back i tried to understand {ggpattern} but didn't get very far. As i understand it, it relies on recreating whole plot layer functions in order to incorporate the pattern fills, and this makes it possible to provide other "image" fills that i think fall outside the core grammar. That is to say, while classic geometric pattern fills make sense to me as a basic {ggplot2} extension that should work well with other extensions, {ggpattern} goes far beyond this, and i'm not prepared to build out {ggalluvial} to match it. I think it would make more sense for someone to make a {ggpattern} extension that introduces alluvial plots.

All that said, i think it would be valuable to have a more core {ggplot2} extension that only provides basic patterns, and that does so through the existing syntax for aesthetic mappings. But i don't have the proficiency with {grid} to build such a package myself. Please let me know if you have any ideas and feel free to invite others to comment. I'd be glad to work with someone to make it happen.

[corybrunson]

@AliceL90 on looking back at {ggpattern} i came across {gridpattern}, which seems to be exactly what i thought did not exist—an extension of {grid} that provides these patterns as graphical objects (grobs). The patterns can be used directly through {ggplot2} without {ggpattern}, as demonstrated here. I haven't tried it with {ggalluvial}; please let me know if it satisfies your needs.

[AliceL90]

Thanks a lot @corybrunson, it did work perfectly :)

[corybrunson]

Excellent! I'll open a new issue to illustrate use with {gridpattern} in a vignette.

[AliceL90]

Great! Thank you