[R] color code from csv

Yihui Xie xieyihui at gmail.com
Sat Oct 4 06:58:18 CEST 2008

So you have two problems: (1) integers to colors (2) hexadecimal
values to colors

They are quite different problems, I think. For the first one, you
have to look at ?palette to know how integers are mapped to colors via
the palette; and the second problem seems to be that 'read.csv()' has
treated '#' as the comment character!! So actually the column has NOT
been read in your 'data'. (print data$color in your console to see if
my guess is correct)

Hope this will make you come down from the wall :-)

BTW, I think Hadley's 'ggplot' package will be more natural for you,
as palette() in 'grDevices' has only 8 colors by default.

Yihui Xie <xieyihui at gmail.com>
Phone: +86-(0)10-82509086 Fax: +86-(0)10-82509086
Mobile: +86-15810805877
Homepage: http://www.yihui.name
School of Statistics, Room 1037, Mingde Main Building,
Renmin University of China, Beijing, 100872, China

On Sat, Oct 4, 2008 at 3:10 AM, kerfuffle <pswi at ceh.ac.uk> 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.
> I could use pch, but I'm already using symbols for another key.
> Grrr.  What am I missing?
> Thanks!
> --
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