R raster functions, splitting multiple rasters from one

Question

I have a simple function splitting a raster object into three different classes. However my function doesn't return these rasters. I also read this tutorial http://cran.r-project.org/web/packages/raster/vignettes/functions.pdf and according to it this is "a really bad way of doing this". However the 'right way' seems overly complicated. Is it really that there is no simple way of doing this (i.e., considering functions should make things easier for you not the vice versa).

I'm quite new to processing rasters with R so forgive me my stupid question..

rm(list=ls(all=T))

r <- raster(ncol=10, nrow=10)
r[] <- rnorm(100,100,5)

# Create split function // three classes
splitrast <- function(rast, quantile) {
  print("Splitting raster...")
  (q <- quantile(rast, probs=quantile))
  r1 <- rast; r2 <- rast; r3 <- rast # copy raster three times

  r1[rast > q[1]] <- NA                    #raster value less than .25 quantile
  r2[rast <= q[1] | rast >= q[2]] <- NA    #raster values is between quantiles
  r3[rast < q[2]] <- NA                    #raster values is over .75 quantile
  par(mfrow=c(1,3))
  plot(r1);plot(r2);plot(r3)
  rast <-   brick(r1,r2,r3)
  return(rast)
}

splitrast(r,c(0.2,0.8))
ls()

EDIT: reproducible example added

Answer 1

Don't try to return them separately. Instead return(list(r1,r2,r3)). But see comments about style.

Answer 2

The R raster subset function can help here. After you return the brick, you can subset each band as separate rasters.

# split the raster - returns a three band stack
rasters = splitrast(r,c(0.2,0.8))

# subset each band of the stack as a separate raster
r1 = subset(rasters, 1)
r2 = subset(rasters, 2)
r3 = subset(rasters, 3)

# proof - plot the separate rasters - same as those plotted in the function
plot(r1);plot(r2);plot(r3)