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Add scalebar to plot

Source: R/scalebar.R
scalebar.Rd

scalebar will get the axis unit and scale information from the closest preceding layer where this information is present. Therefore, the placement of scalebar in the sequence of layers is important.

Usage

scalebar(len = NULL, col = "red", lwd = 1, xrel = 0.05, yrel = 0.05)

Arguments

len

scalar numeric giving the length of the scalebar in physical coordinate space; the unit will be extracted from the data's Zarr specifications (see axes(x)).

col

string indicating the color to use for the scalebar.

lwd

scalar numeric indicating the linewidth to use for the scalebar.

xrel, yrel

scalar numeric indicating relative position of the scalebar.

Value

length-two list of ggplot2::annotate() layers corresponding to scalebar line (geom="segment") and unit label (geom="text")

Examples

zs <- file.path("extdata", "blobs.zarr")
zs <- system.file(zs, package="spatialdataR")
sd <- readSpatialData(zs, tables=FALSE)

# mock unit (data misses specification!)
md <- meta(image(sd, 2))
md$multiscales[[1]]$axes[[3]]$unit <- "micron"
sd$images[[2]]@meta <- md

plotSpatialData(sd) + 
  plotImage(i=2) + 
  scalebar(len=10)