[R] color code from csv

Jim Lemon jim at bitwrit.com.au
Sun Oct 5 12:04:44 CEST 2008


kerfuffle wrote:
> hi folks,
>
> this is driving me up the wall.  Apologies for posting twice in the same
> week, I'm writing up a thesis.  I wish to color-code some dots in an xy
> plot.  I've got a csv file with various elements, one of which is the
> color-key (with the header 'color').  If the color-key is decimal (eg.
> 1,2,3) then I can use
> plot (X ~ Y, col=data$color) 
> The problem, however, is that using decimal numbers I can only produce 8
> colors.  It starts to recyle them after that (so, if possible values of my
> color column are 1,2,3,4,5,6,7,8,9,10,11, the values 1 and 9 both produce
> red, 2 and 10 produce black).  However, I knew I could get more colors by
> using hexadecimal (tested with the legend)  So, I carefully produced a csv
> file with hexadecimal values instead of decimal ones (eg. elements in the
> column are #ffffff, #ff0000) but if I use col=data$color it doesn't work,
> the entire plot is white.  If I use these set of hexadecimal values in the
> legend, it works fine and I get lovely colors.  
>
>   
Hi kerfuffle,
You might want to look at color.scale in the plotrix package that 
transforms numeric values into colors as well as the rainbow function 
that Sarah mentioned.

Jim



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