[R] colored rasterImage()

Michael Sumner
Fri, 01 Oct 2010 04:26:07 -0000

Use the matrix of colours directly:

nx <- 100
ny <- 100
m <- matrix(data = rep(seq(0,1, length = nx), ny), ncol = nx, nrow ny, byrow
= TRUE)
plot(1:nx, 1:ny, type = "n")
my.color <- matrix(data = (rainbow(100))[m*100], ncol = nx, nrow = ny,
byrow = TRUE)
rasterImage(my.color, 1, 1, nx, ny)


Also, you might want to check out image.SpatialGridDataFrame in
package sp that provides a wrapper around rasterImage for
SpatialGrids.

 I'm not aware of other examples, but I have not looked hard since the
first release of rasterImage.

library(sp)
sp:::image.SpatialGridDataFrame

Cheers, Mike.

On Fri, Oct 1, 2010 at 12:50 PM, Ben Tupper <ben.bighair at gmail.com>
wrote:
> Hello,
>
> I have been exploring the possibility to transition some code that
currently
> uses image() to use the new rasterImage(). ?To date, I haven't been
able to
> specify a color look-up strategy that works. ?For example...
>
> nx <- 100
> ny <- 100
> m <- matrix(data = rep(seq(0,1, length = nx), ny), ncol = nx, nrow = ny,
> byrow = TRUE)
> plot(1:nx, 1:ny, type = "n")
> my.color <- matrix(data = (rainbow(100))[m*100], ncol = nx, nrow = ny,
byrow
> = TRUE)
> rasterImage(m, 1, 1, nx, ny, col = my.color)
>
> This yields a greyscale image. Is it possible to create colored images
using
> rasterImage, and, if so, what is the correct way to generate a colored
image
> using rasterImage?
>
> Also, is there a vignette or tutorial on using the new rasterImage() and
> related functions?
>
> Thanks!
> Ben Tupper
> Bigelow Laboratory for Ocean Science
> www.bigelow.org
>
>> R.Version()
> $platform
> [1] "i386-apple-darwin9.8.0"
>
> $arch
> [1] "i386"
>
> $os
> [1] "darwin9.8.0"
>
> $system
> [1] "i386, darwin9.8.0"
>
> $status
> [1] ""
>
> $major
> [1] "2"
>
> $minor
> [1] "11.1"
>
> $year
> [1] "2010"
>
> $month
> [1] "05"
>
> $day
> [1] "31"
>
> $`svn rev`
> [1] "52157"
>
> $language
> [1] "R"
>
> $version.string
> [1] "R version 2.11.1 (2010-05-31)"
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



--
Michael Sumner
Institute for Marine and Antarctic Studies, University of Tasmania
Hobart, Australia
e-mail: mdsumner at gmail.com