From: Jim Lemon <bitwrit_at_ozemail.com.au>

Date: Tue 10 Jan 2006 - 01:47:02 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Mon Jan 09 09:50:32 2006

Date: Tue 10 Jan 2006 - 01:47:02 EST

Martin Erwig wrote:

> Considering the R function/plot shown below, I wonder whether

*> it is possible to do the following changes:
**>
**> (1) Change the color of each point to be picked from
**> list of colors according to its z-value. (The range
**> should be from blue (z=0) to red (z=1).) The grid
**> should then be omitted. [I have seen "terrain.colors", but
**> don't know how to use it for this purpose.]
**>
**> (2) Add two lines to the surface for, say z=0.8 and
**> z=0.3. [Can contour or contourLines be used?]
**>
**>
**> ---
**>
**> x <- seq(0, 1, length = 50)
**> y <- x
**> f <- function(x,y) { sin ((1-x)*y) }
**> z <- outer(x,y,f)
**>
**> persp(x, y, z,
**> theta = 30, phi = 30,
**> shade = 0.3, col = "red"
**> )
**>
**> ---
**>
**>
**> Finally, I would also produce a flattened 2D map
**> of the same function, i.e. a map in which each point
**> (x,y) is mapped to a color in a range according to
**> f(x,y). Also two lines for f(x,y)=c1 and f(x,y)=c2
**> should be added.
**>
**>
**> Is this possible?
**>
*

Hi Martin,

The function color.scale will linearly transform numeric values into colors between arbitrary color endpoints specified as red, green and blue:

Your example would be

redrange=c(0,1),greenrange=c(0,0),bluerange=c(1,0).

For the 2D plot, have a look at color2D.matplot. Both are in the plotrix package.

You might also want to look at colorRampPalette in the grDevices package.

Jim

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Mon Jan 09 09:50:32 2006

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