Calculate Kendall rank-correlation coefficietn between 2 rasters

kendall_raster.R

library(raster)
library(dismo)

# Sample both raster with the same points
sample.points <- randomPoints(raster1, 500000)

# Extract raster values at sample point locations
sample.raster1 <- extract(raster1, sample.points,method='simple', na.rm=TRUE)
sample.raster2 <- extract(raste2, sample.points,method='simple', na.rm=TRUE)

# use="complete.obs" needed here, beacause raster2 might have NA where raster1 hasn't which will propagate as NA otherwise
correlation <- cor(sample.raster1, sample.raster1, method="kendall", use="complete.obs")