Add subfigure number independent of strip text label

Question

I would like to find an easy solution to numbering subfigures as this is a very standard exercise of my work. I could do this by arranging the plots and automatically adding number via e.g. egg::ggarrange(). However, this gets complicated and especially ugly if I have a ggplot that is already split into facets via facet_grid() and with a long strip text. I already asked a similar question here.

In publications I would usually want to have subfigures with a label at the top left or right corner like 1, 2, 3... or A, B, C,... and subfigure text label describing the facet centered on top. Both, the label and the text should be independent from each other. Looking at the solution of @stefan in my above mentioned question, the labels and text are obviously not independent from each other and the labels are not left-aligned.

I wonder, is there maybe a function that puts labels like 1, 2, 3... or A, B, C,... left-aligned on top of the top-right corner of the facet independent of the (centered) strip text itself? That would be awesome and would save me a lot of hassle.

I could obviously just use a label like "<b>1</b> Text label" and left align it. But this looks really ugly if I have a very long text. What I want to achieve is rather a numeric label on the left and a text label spanning two lines.

An acceptable solution would be to split the strip text into two columns that are independent from each other. This way I could put a number left-aligned and centered a text label over two lines.

Have you looked at [tagger](https://github.com/eliocamp/tagger)? — teunbrand, Apr 06 '21 at 08:59
No I haven't! Thanks for the info, I will have a look into it :) — bamphe, Apr 06 '21 at 09:00

score 0 · Answer 1 · answered Apr 06 '21 at 09:50

Thanks to @stefan I had a look at the tagger package. I find the tag_facets() function to be a bit hard to work with (especially the positioning).

However, I noticed that I already have the tag_facet() function (without the s!) from the egg package and decided to give it a try. This changes the margins of the plot in an unfortunate way and sets strip text to element_blank(), but this is pretty easy to revert (similar solution presented here in the answer by @Lyngbakr).

I just add this to my plot and it works nicely:

egg::tag_facet(p, tag_pool = 1:5, open = "", close = "", vjust = -0.7) +
  coord_cartesian(clip = "off") +
  theme(strip.text = element_text(),
        legend.margin=margin(0,0,0,0),
        legend.box.margin=margin(-10,-10,-10,-10))

(Although it would be more intuitive, this does not seem to work with the egg::tag_facet_outside() function though...)

Add subfigure number independent of strip text label

1 Answers1