[R] setting color ranges

[Achim Zeileis]

On Thu, 14 Feb 2008, samsr wrote:

>
> Hi,
>
>  I need to plot a matrix using image() such that negative values are easily
> distinguishable from posittive values, while also maintaining a gradation in
> color with magnitude. How can I set ranges for colors in order to achieve
> this. Thanks.

Look at the function diverge_hcl() in package "vcd" which provides
diverging palettes. You can find several examples in
  example("diverge_hcl", package = "vcd")
  vignette("hcl-colors", package = "vcd")

Further background information is available in this technical report by
Kurt Hornik, Paul Murrell and me
  http://epub.wu-wien.ac.at/dyn/openURL?id=oai:epub.wu-wien.ac.at:epub-wu-01_c87

Best,
Z

> Sam
> --
> View this message in context: http://www.nabble.com/setting-color-ranges-tp15489086p15489086.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>
>