[R] Color index in image function

[Bernardo Rangel Tura]

On Sat, 2009-09-05 at 04:14 -0700, FMH wrote:
> Dear All,
> 
> I was looking for the color index in image function, such as from topo.colors(n) and etc. but still never found it. For instance, from the help menu.
> 
> 
> ###########################################
> # Volcano data visualized as matrix. Need to transpose and flip
> # matrix horizontally.
> image(t(volcano)[ncol(volcano):1,])
> 
> # A prettier display of the volcano
> x <- 10*(1:nrow(volcano))
> y <- 10*(1:ncol(volcano))
> image(x, y, volcano, col = terrain.colors(100), axes = FALSE)
> contour(x, y, volcano, levels = seq(90, 200, by = 5),
>         add = TRUE, col = "peru")
> axis(1, at = seq(100, 800, by = 100))
> axis(2, at = seq(100, 600, by = 100))
> box()
> title(main = "Maunga Whau Volcano", font.main = 4)
> #########################################
> 
> >From the script above, it yields a beautiful  image of volcano with variety of colors but i have to list down the color index that could show the meaning of each color in my thesis. 
> 
> Could someone please help me to extract this color index?
> 
> Thank you
> Fir

If I understand your question you need change the Palette of image plot.

So you need use "colorRampPalette" look my example

Brazilan.Pallete <- colorRampPalette(c("green","yellow", "blue"))
image(x, y, volcano, col = Brazilan.Pallete(50), axes = FALSE)

-- 
Bernardo Rangel Tura, M.D,MPH,Ph.D
National Institute of Cardiology
Brazil