R: Examples for 'grDevices::is.raster'

### ** Examples

# A red gradient
as.raster(matrix(hcl(0, 80, seq(50, 80, 10)),
                 nrow = 4, ncol = 5))

     [,1]      [,2]      [,3]      [,4]      [,5]     
[1,] "#C54E6D" "#C54E6D" "#C54E6D" "#C54E6D" "#C54E6D"
[2,] "#E16A86" "#E16A86" "#E16A86" "#E16A86" "#E16A86"
[3,] "#FE86A1" "#FE86A1" "#FE86A1" "#FE86A1" "#FE86A1"
[4,] "#FFA2BC" "#FFA2BC" "#FFA2BC" "#FFA2BC" "#FFA2BC"

# Vectors are 1-column matrices ...
#   character vectors are color names ...
as.raster(hcl(0, 80, seq(50, 80, 10)))

     [,1]     
[1,] "#C54E6D"
[2,] "#E16A86"
[3,] "#FE86A1"
[4,] "#FFA2BC"

#   numeric vectors are greyscale ...
as.raster(1:5, max = 5)

     [,1]     
[1,] "#333333"
[2,] "#666666"
[3,] "#999999"
[4,] "#CCCCCC"
[5,] "#FFFFFF"

#   logical vectors are black and white ...
as.raster(1:10 %% 2 == 0)

      [,1]     
 [1,] "#000000"
 [2,] "#FFFFFF"
 [3,] "#000000"
 [4,] "#FFFFFF"
 [5,] "#000000"
 [6,] "#FFFFFF"
 [7,] "#000000"
 [8,] "#FFFFFF"
 [9,] "#000000"
[10,] "#FFFFFF"

# ... unless nrow/ncol are supplied ...
as.raster(1:10 %% 2 == 0, nrow = 1)

     [,1]      [,2]      [,3]      [,4]      [,5]      [,6]      [,7]     
[1,] "#000000" "#FFFFFF" "#000000" "#FFFFFF" "#000000" "#FFFFFF" "#000000"
     [,8]      [,9]      [,10]    
[1,] "#FFFFFF" "#000000" "#FFFFFF"

# Matrix can also be logical or numeric (or raw) ...
as.raster(matrix(c(TRUE, FALSE), nrow = 3, ncol = 2))

     [,1]      [,2]     
[1,] "#FFFFFF" "#000000"
[2,] "#000000" "#FFFFFF"
[3,] "#FFFFFF" "#000000"

as.raster(matrix(1:3/4, nrow = 3, ncol = 4))

     [,1]      [,2]      [,3]      [,4]     
[1,] "#404040" "#404040" "#404040" "#404040"
[2,] "#808080" "#808080" "#808080" "#808080"
[3,] "#BFBFBF" "#BFBFBF" "#BFBFBF" "#BFBFBF"

# An array can be 3-plane numeric (R, G, B planes) ...
as.raster(array(c(0:1, rep(0.5, 4)), c(2, 1, 3)))

     [,1]     
[1,] "#008080"
[2,] "#FF8080"

# ... or 4-plane numeric (R, G, B, A planes)
as.raster(array(c(0:1, rep(0.5, 6)), c(2, 1, 4)))

     [,1]       
[1,] "#00808080"
[2,] "#FF808080"

# subsetting
r <- as.raster(matrix(colors()[1:100], ncol = 10))
r[, 2]

      [,1]         
 [1,] "aquamarine3"
 [2,] "aquamarine4"
 [3,] "azure"      
 [4,] "azure1"     
 [5,] "azure2"     
 [6,] "azure3"     
 [7,] "azure4"     
 [8,] "beige"      
 [9,] "bisque"     
[10,] "bisque1"

r[2:4, 2:5]

     [,1]          [,2]      [,3]     [,4]        
[1,] "aquamarine4" "bisque3" "brown"  "cadetblue" 
[2,] "azure"       "bisque4" "brown1" "cadetblue1"
[3,] "azure1"      "black"   "brown2" "cadetblue2"

# assigning to subset
r[2:4, 2:5] <- "white"

# comparison
r == "white"

       [,1]  [,2]  [,3]  [,4]  [,5]  [,6]  [,7]  [,8]  [,9] [,10]
 [1,]  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [2,] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE
 [3,] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE
 [4,] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE
 [5,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [6,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [7,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [8,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [9,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[10,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

## Don't show: 
stopifnot(r[] == r,
          identical(r[3:5], colors()[3:5]))
r[2:4] <- "black"
stopifnot(identical(r[1:4, 1], as.raster(c("white", rep("black", 3)))))
## End(Don't show)

Examples for 'grDevices::is.raster'

Create a Raster Object