## ----raster-3a----------------------------------------------------------------
# create an empty RasterLayer
library(raster)
r <- raster(ncol=10, nrow=10)
# assign values to cells
values(r) <- 1:ncell(r)
s <- r + 10
s <- sqrt(s)
s <- s * r + 5
r[] <- runif(ncell(r))
r <- round(r)
r <- r == 1


## ----raster-3b----------------------------------------------------------------
s[r] <- -0.5
s[!r] <- 5
s[s == 5] <- 15


## ----raster-3c----------------------------------------------------------------
r <- raster(ncol=5, nrow=5)
r[] <- 1
s <- stack(r, r+1)
q <- stack(r, r+2, r+4, r+6)
x <- r + s + q
x


## ----raster-3d----------------------------------------------------------------
a <- mean(r,s,10)
b <- sum(r,s)
st <- stack(r, s, a, b)
sst <- sum(st)
sst


## ----raster-3e----------------------------------------------------------------
cellStats(st, 'sum')
cellStats(sst, 'sum')