From: Don MacQueen <macq_at_llnl.gov>

Date: Fri 30 Dec 2005 - 04:05:10 EST

}

Date: Fri 30 Dec 2005 - 04:05:10 EST

I have found this little function useful when trying to choose colors:

showcols <- function (indx = 0:6)

{

for (ii in unique(indx)) { is <- 100 * ii + 1:100 if (min(is) > length(colors())) { cat("Maximum value of arg is", floor(length(colors())/100), "\n") return(NULL) } foo <- matrix(colors()[is], nrow = 10) par(mar = c(3, 3, 0.25, 0.25)) plot(1:10, 1:10, type = "n", yaxt = "n", xlab = "", ylab = "") axis(2, at = 1:10, lab = 10:1) for (j in 1:10) { for (i in 1:10) { points(j, 11 - i, col = foo[i, j], pch = 16, cex = 4) text(j, 11 - i - 0.3, foo[i, j], cex = 0.8) } } if (length(indx) > 1 & ii < max(indx)) readline(paste("Currently showing group", ii, " CR to continue ")) } invisible(foo)

}

Just type

showcols()

at the R prompt. Then pick any 20 you happen to think are distinguishable.

Based on my own experience, I would doubt that it is possible to find
20 easily distinguishable colors.

But perhaps if you use both solid and dotted lines you can get 20
distinguishable lines.

-Don

At 10:48 AM +0800 12/28/05, Vincent Deng wrote:

*>Hi,
**>
*

>Thanks for your kindly reply.

*>I think maybe I didn't specify color codes properly. That is,the
**>difference between each color is not sharp enough for me to identify
**>them as different colors.
**>
**>So can you tell me about how to specify the color properly so that the
**>difference among each color can be identified clearly?
**>
**>Thanks again and again ...
**>
**>On 12/27/05, Uwe Ligges <ligges@statistik.uni-dortmund.de> wrote:
**>> Vincent Deng wrote:
**>>
**>> > Dear Uwe,
**>> >
**>> > Sorry, I did not describe my question clearly. I created a matrix to
**>> > store color code using rgb function.
**>> >
**>> > abc = rgb(6:36,0,0,maxColorValue = 255)
**>> >
**>> > And after running codes like this
**>> >
**>> > for (i in c(1:20))
**>> > {
**>> > points(...,...,col=abc[i])
**>> > lines(...,col=abc[i])
**>> > }
**>> >
**>> > R still used 8 colors of abc color codes repeatedly to draw the diagram
**>> >
**>> > Any helps?
**>>
**>>
**>> No, it does not (in fact, all appears to be more or less black on my
**>> screen ;-)). Another example:
**>>
**>> plot(1:255, col=rgb(1:255,0,0,maxColorValue = 255))
**>>
**>> Uwe Ligges
**>>
**>>
**>>
**>> > Best Regards...
**>> >
**>> > On 12/27/05, Uwe Ligges <ligges@statistik.uni-dortmund.de> wrote:
**>> >
**>> >>Vincent Deng wrote:
**>> >>
**>> >>>Hi,
**>> >>>
**>> >>>I'm a new hand in R language. I have about 20 groups of data[x,y] and
**>> >>>want to plot them on a graph. To do this, I write a for-loop as
**>> >>>following: (some codes are omitted for simplicity)
**>> >>>
**>> >>>for (i in c(1:20))
**>> >>>{
**>> >>> points(...,...,col=i)
**>> >>> lines(...,col=i)
**>> >>>}
**>> >>>
**>> >>>The problem is "R only plot them with 8 colors repeatly". Could anyone
**>> >>>help me solve this problem? Or is there any package providing plot
**>> >>>function without color limit?
**>> >>
**>> >>
**>> >>After typing
**>> >>
**>> >> ?colors
**>> >>
**>> >>I get a nice help page that points me to a lot of other functions that
**>> >>generate more than 8 colors. Maybe your installation of R is broken and
**>> >>you cannot see this help page? You certainly tried to get help on colors
**>> >>as well.
**>> >>
**>> >>There is no limit of the color number in the functions above, simply
**>> >>specify the color you want to get. The only color limit applies for the
**>> >>device and for most devices and rgb colors this is 256^3.
**> > >>
**> > >>Uwe Ligges
**> > >>
**> > >>
**> > >>
**> > >>
**> > >>
**> > >>>Best Regards...
**> > >>>
**> > >>>______________________________________________
**> > >>>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
**>> >>
**>> >>
**>>
**>>
**>
**>______________________________________________
**>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
*

-- -------------------------------------- Don MacQueen Environmental Protection Department Lawrence Livermore National Laboratory Livermore, CA, USA ______________________________________________ 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.htmlReceived on Fri Dec 30 04:14:46 2005

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