[R] Strategy for creating a palette...?

[Peter Dalgaard BSA]

Kjetil Kjernsmo <kjetil.kjernsmo at astro.uio.no> writes:

> Dear all,
> 
> I'm generally not a big fan of GUIs, but I have just discovered one thing
> where a GUI would be a nice thing: creating color palettes.

Actually not. Just take a program which allows you to customize colors
graphically and try to match the selection to an existing color.

> I'm creating an "image", for transparencies for a lecture I'm giving, so
> this is going to look great... :-) What I'm out for, is to make green
> tones and red tones, and a relatively sharp break between them. This break
> will signify a rejection region for a test.
> 
> I've spent all evening, er, night trying to tune this, but it's still
> ugly. My best shot so far is this:
> greenred <- palette(rgb(exp(-(0:255)/80), exp(-(0:255)/80), 0))

Um, that doesn't mean what I think you think it means.

Point 1: palette() returns the previous palette:

> greenred <- palette(rgb(exp(-(0:255)/80), exp(-(0:255)/80), 0))
> greenred
[1] "black"   "red"     "green3"  "blue"    "cyan"    "magenta" "yellow" 
[8] "white"  

Point2: rgb(exp(-(0:255)/80), exp(-(0:255)/80), 0) have equal amounts
of red and green, so is varying degrees of dirty yellow.

> Any ideas...? Anybody got a pretty palette for this purpose? Also, I'd
> like to tune the palette so that the break between green and red happens
> at a value of e.g. 0.05. How would I do that?

A code example that actually worked might have helped us...
Instinctively, I'd suggest you should play with hsv().


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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