## ----raster-1a----------------------------------------------------------------
library(raster)
# RasterLayer with the default parameters
x <- raster()
x

# With other parameters
x <- raster(ncol=36, nrow=18, xmn=-1000, xmx=1000, ymn=-100, ymx=900)
# that can be changed
res(x)

# change resolution
res(x) <- 100
res(x)
ncol(x)
# change the numer of columns (affects resolution)
ncol(x) <- 18
ncol(x)
res(x)

# set the coordinate reference system (CRS) (define the projection)
projection(x) <- "+proj=utm +zone=48 +datum=WGS84"
x


## ----raster-1b, fig=TRUE , echo=TRUE------------------------------------------
r <- raster(ncol=10, nrow=10)
ncell(r)
hasValues(r)

# use the 'values' function
# e.g., 
values(r) <- 1:ncell(r)
# or
set.seed(0)
values(r) <- runif(ncell(r))

hasValues(r)
inMemory(r)
values(r)[1:10]

plot(r, main='Raster with 100 cells')


## ----raster-1c, echo=TRUE-----------------------------------------------------
hasValues(r)
res(r)
dim(r)
xmax(r)

# change the maximum x coordinate of the extent (bounding box) of the RasterLayer
xmax(r) <- 0

hasValues(r)
res(r)
dim(r)

ncol(r) <- 6
hasValues(r)
res(r)
dim(r)
xmax(r)


## ----raster-2a, fig=TRUE , echo=TRUE------------------------------------------
# get the name of an example file installed with the package
# do not use this construction of your own files
filename <- system.file("external/test.grd", package="raster")

filename
r <- raster(filename)
filename(r)
hasValues(r)
inMemory(r)
plot(r, main='RasterLayer from file')


## ----raster-2b----------------------------------------------------------------
# create three identical RasterLayer objects
r1 <- r2 <- r3 <- raster(nrow=10, ncol=10)
# Assign random cell values 
values(r1) <- runif(ncell(r1))
values(r2) <- runif(ncell(r2))
values(r3) <- runif(ncell(r3))

# combine three RasterLayer objects into a RasterStack
s <- stack(r1, r2, r3)
s
nlayers(s)

# combine three RasterLayer objects into a RasterBrick 
b1 <- brick(r1, r2, r3)
# equivalent to:
b2 <- brick(s)

# create a RasterBrick  from file
filename <- system.file("external/rlogo.grd", package="raster")
filename
b <- brick(filename)
b
nlayers(b)

# extract a single RasterLayer
r <- raster(b, layer=2)
# equivalent to creating it from disk
r <- raster(filename, band=2)