What are ‘components’ in tmap?
Components are non-spatial parts of the plots:
- titles and credits: [tm_title()] and [tm_credits()]
- scale bars and compasses: [tm_scalebar()] and [tm_compass()]
- legends: specified with the
.legendcompoments in the data layer functions (e.g. [tm_polygons()]).
Title and credits
tm_title() and tm_credits() add text to the map in the form a title and a credits/attribution text respectively. The underlying function and all the options are the same, but the default values differ: titles are by default larger and placed above the map (outside the frame), while credits are place inside the frame at the bottom right.
tm_shape(NLD_muni) +
tm_polygons(
fill = "edu_appl_sci") +
tm_title("Population share with (applied) university degree in 2022") +
tm_credits("Statistics Netherlands (CBS)")
Scale bar and compass
tm_shape(NLD_muni) +
tm_polygons() +
tm_compass(type = "8star") +
tm_scalebar()
Positioning of components (basics)
The position of a map component can be specified with the general argument position.
It takes a vector of two, the first is the horizontal position ("left", "center", "right"), the second one the vertical position ("top", "center", "bottom")
tm_shape(NLD_muni) +
tm_polygons(
fill = "edu_appl_sci",
fill.legend = tm_legend(position = c("left", "top"))) +
tm_credits("Statistics Netherlands (CBS)", position = c("left", "bottom")) +
tm_compass(type = "8star", position = c("right", "bottom")) +
tm_scalebar(position = c("right", "bottom"))
If the components should be placed tighter to the frame, use capital case instead; e.g. c("LEFT", "BOTTOM") in stead ofc(“left”, “bottom”)`.
There are much more options to position map componets via tm_pos(), see the vignette about positions