The task: I'm creating a function to assess flood damage in R. The inputs are:

• Dataframe with water depth values and corresponding damage values in percentage.
• Raster representing water depth

The raster values must be approximated to the closest value in the first column of the df and then create a new raster with damage values using corresponding values from the second column).

library(raster)
damage <- cbind(c(0.0,0.2,0.4,0.6,0.8,1.0),c(0, 5, 10, 40, 70, 100))
r.wd <- raster(myraster.tif)

I've tried using which.min(abs(damage[,1]-r.wd)) but doesn't work.