R help - Aug 2001 - Strategy for creating a palette...?

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.

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))
greenred2 <- greenred[c(1:160, 220:256)]
and use greenred2.

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?

Best,

Kjetil
-- 
Kjetil Kjernsmo
Graduate astronomy-student                    Problems worthy of attack
University of Oslo, Norway            Prove their worth by hitting back
E-mail: kjetikj at astro.uio.no                                - Piet Hein
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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().


-- 
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