offsetGridText {Orcs}

Insert Offset Text Annotation into trellis Plot

Description

This is a wrapper function around Orcs:::calcOffsetGridText and grid based text drawing functions (currently including grid::grid.text() and grid.stext()) that automatically adds offset text annotations to a trellis plot.

Usage

offsetGridText(
  x,
  y = NULL,
  labels,
  xlim = NULL,
  ylim = NULL,
  pos = NULL,
  stext = FALSE,
  offset = 0.02,
  ...
)

Arguments

x

A numeric vector containing x coordinates, or a 2-column matrix containing x and y coordinates.

y

A numeric vector containing y coordinates, or NULL if 'x' is a two-column matrix.

labels

The text to be written as character.

xlim, ylim

X and Y-axis limits (c(min, max)) of the current plot. If not supplied, limits are automatically calculated from supplied x and y coordinates.

pos

Text position specifier(s) as integer used by graphics::text(). If not supplied, optimal text positions will be determined with respect to neighboring locations using plotrix::thigmophobe().

stext

logical, defaults to FALSE. If TRUE, shadow text will be drawn around 'labels'.

offset

A numeric offset in normalized parent coordinates ("npc", see grid::unit()).

...

Additional arguments passed to the respective grid text drawing function (depends on 'stext').

Author(s)

Florian Detsch

Examples

KiLi = terra::rast(system.file("extdata/KiLi.tif", package = "Orcs"))

# kilimanjaro peaks
peaks = data.frame(Peak = c("Kibo", "Mawenzi", "Shira")
                   , Lon = c(37.359031, 37.455061, 37.210408)
                   , Lat = c(-3.065053, -3.095436, -3.038222))

peaks = sf::st_as_sf(peaks, crs = 4326, coords = c("Lon", "Lat"))

# visualization
xlim_kili <- c(37.15, 37.55)
ylim_kili <- c(-3.25, -2.9)

if (requireNamespace("raster", quietly = TRUE)) {
   p = raster::spplot(KiLi[[1]], col.regions = "transparent", colorkey = FALSE, 
              xlim = xlim_kili, ylim = ylim_kili,
              scales = list(draw = TRUE, y = list(rot = 90)), 
              sp.layout = rgb2spLayout(KiLi, quantiles = c(0, 1), alpha = .8)) + 
     latticeExtra::layer(sp.points(as(peaks, "Spatial"), cex = 1.5, pch = 20, col = "black"))
   
   print(p)
   
   grid::downViewport(lattice::trellis.vpname(name = "figure"))
   offsetGridText(x = sf::st_coordinates(peaks), labels = peaks$Peak,  
                  xlim = xlim_kili, ylim = ylim_kili, stext = TRUE, offset = .02,
                  gp = grid::gpar(fontsize = 16))
}