Question: tm_text
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Nowosad commented
@mtennekes could you tell me (or point me to the code) how tm_text()
relates to other layer types. I assume it just uses coordinates of points, and centroids (??) of lines and polygons?
mtennekes commented
Yes, exactly. tm_text
uses spatial points, just like tm_symbols
. For (multi)polygons/lines, the centroids are used, but there are a few options: see tm_shape
's options point.per
and line.center
.
In v4, I plan to separate this 'geometry transformation' part into single functions that can be specified in the layer functions. E.g.
tm_text("name",
size = "population",
size.setup = tm_aes_cont(legend.sizes = c(10, 20, 30)*1e6),
geom = tm_geom_centroid(per.feature = TRUE))
I plan to start writing the chapter 'tmap extensions' while working on v4. Then we can iteratively exchange ideas.
Nowosad commented
The 'tmap extensions' chapter sounds great!