Doh! Of course!
Thanks for this. I convinced myself that the input image to
rasterImage() had to be scaled 0-1. I think I started down that path
by trying the following with as.raster() ...
> m <- matrix(data = rep(seq(0,3, length = nx), ny), ncol = nx, nrow
= ny, byrow = TRUE)
> r <- as.raster(m)
Error in rgb(tx, tx, tx, max = max) :
color intensity 1.0303, not in [0,1]
And my next step was to follow the examples for rasterImage() which
use 0-1. I'm glad to be straightened out.
Thanks,
Ben
On Oct 1, 2010, at 12:26 AM, Michael Sumner wrote:
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.bigh...@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)"
______________________________________________
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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: mdsum...@gmail.com
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
