[R] Log color scale

[Thomas Lumley]

On Sun, 30 Jul 2006, Uwe Ligges wrote:

> vincent at 7d4.com wrote:
>
>> Kartik Pappu a écrit :
>>
>>
>>> However I need to plot my data in a log transformed color scale.  Is
>>> this possible?  I will be happy to explain further, but basically I
>>> need to do this because there are large variations in the max and min
>>> values of my raw data and I am trying to highlight the differences in
>>> the values at the lower end of my raw data (while still displaying the
>>> values at the high end of the spectrum for comparison) so if figured
>>> the best way to represent this on a (RGB) color scale is to do it with
>>> a log transform.  I do not want to use too many colors because that
>>> make the figure too busy.
>>> Any suggestions on how to achieve this.
>>
>>
>> Don't use too much time to search a good palette, build it yourself.
>
> It is worth looking into the packages "RColorBrewer" and "colorspace".
> Some people thought about colors in graphics and wrote some code that
> might result in more appropriate colors and palettes than those that are
> quickly hacked...
>

colorRampPalette() will interpolate between colors (eg those from one of 
the ColorBrewer palettes) and has a bias= argument to make the colors 
closer together at one end of the scale.

 	-thomas

Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle