将曲线添加到栅格地图？

Question

would it be possible to add isoclines or something like "filled.contour" to a raster map?

Eg to a Bioclim variable? (RasterLayer)

# Download Bioclim data 
library(dismo)
tmin_06<-getData("worldclim", var="tmin", res=0.5, lon=10, lat=70)
# plot tmin 
plot(tmin$tmin1_06)

And then add e.g. filled.contour {graphics}

I can't seem to extract the correct values from the RasterLayer and get an error massage: "cannot coerce type 'S4' to vector of type 'double'"

Or what would you use to illustrate the direction of change in a map like this for temperature, or for equidistance in an elevation map?

Thank you!

Daniel

Answer 1

Here are two approaches:

# example data
f <- system.file("external/test.grd", package="raster")
r <- raster(f)

plot(r)
contour(r, add=TRUE)

# or
filledContour(r)