## ----raster-15----------------------------------------------------------------
library(terra)
r <- rast(ncol=36, nrow=18)
ncol(r)
nrow(r)
ncell(r)
rowFromCell(r, 100)
colFromCell(r, 100)
cellFromRowCol(r,5,5)
xyFromCell(r, 100)
cellFromXY(r, cbind(0,0))
colFromX(r, 0)
rowFromY(r, 0)


## ----raster-20----------------------------------------------------------------
r <- rast(system.file("ex/meuse.tif", package="terra"))
v <- values(r)
v[708:712]


## ----raster-21----------------------------------------------------------------
cells <- cellFromRowCol(r, 50, 35:39)
cells
r[cells]
xy <- xyFromCell(r, cells)
xy
extract(r, xy)


## ----raster-32----------------------------------------------------------------
#r[cells] 
#r[1:4]
#sources(r)
#r[2:3] <- 10
#r[1:4]
#sources(r)


## ----raster-33----------------------------------------------------------------
#r[1]
#r[2,2]
#r[1,]
#r[,2]
#r[1:3,1:3]

# keep the matrix structure
#r[1:3,1:3, drop=FALSE]