Why is geom_text size in mm?

ggplot2

#1

i’m unclear on why geom_text's size unit is mm and not mm/the magic number in ggplot2:::.pt. Also why it is apparently unaffected by global changes in text size via theme() is there a rationale for geom_text being excluded from these behaviours?

Some others who seem a little unclear on this:



https://github.com/tidyverse/ggplot2/issues/1828


#2

a) To match the sizes of points and lines

b) Because theme settings only affect non-data components of the plot. (Although we might change this in the future: https://github.com/tidyverse/ggplot2/issues/2239)


#3

Thanks Hadley,

I intutively mapped geom_text() into a mental category of ‘texty’ things which have font sizes, not into the category of ‘data-pointy’ things which don’t. Depending on what proportion of people put this in what mental category it might make more sense from a user-friendliness perspective to default to font sizes and have people transform it by the magic number to get mm if they want.

I agree with the poster of that issue that expanding themes to affect non-data components seems like a good idea.