add vertical and/or horizontal lines to a map made with terra

Adaptation of abline that allows adding a horizonal or vertical lines to a map. This function will place the lines in the locations within the mapped area as delineated by the axes. It is meant to be used when you specifiy your own tick marks, such that add_grid does not work.

Also see graticule

Usage

add_abline(h=NULL, v=NULL, ...)

Arguments

h

the y-value(s) for horizontal line(s)

v

the x-value(s) for vertical line(s)

...

additional graphical parameters for drawing lines

See also

add_grid, graticule, add_legend, add_box, add_grid, add_mtext

Examples

v <- vect(system.file("ex/lux.shp", package="terra"))
atx <- seq(xmin(v), xmax(v), .1)
aty <- seq(ymin(v), ymax(v), .1)
plot(v, pax=list(xat=atx, yat=aty), ext=ext(v)+.2)
add_abline(h=aty, v=atx, lty=2, col="gray")