[R] lattice xyplot: plot multiple lines with different colors

[Chuck Cleland]

Bram Kuijper wrote:
> Hi everyone,
> 
> I am using the lattice package to plot some simulation results, by using 
> the function xyplot(). However, I cannot find a way to plot multiple 
> lines within the same xyplot and to have each of the lines be drawn in a 
> different color.
> 
> This is what I am currently doing:
> 
> xyplot(a + b + c ~ x, my_data, panel = panel.lines)
> 
> but, of course, all lines are drawn in the same color.
> 
> 
> What I would prefer, would be to first print a single line in an xyplot 
> and then add a new line, and so on (since I want to dynamically 
> determine the number of lines that need to be plotted). For example, 
> something like this would be nice:
> 
> for(i = 1:length(lines_to_be_drawn)) {
>      xyplot(lines_to_be_drawn[i] ~ x, my_data, panel = {some function 
> setting a different color});
> 
> 	// do some other functions like plotting legend, parameters
> }
> 
> (although in this putative example, a new xyplot is drawn over the old 
> one every time).
> 
> anyone any idea to plot multiple lines with different colors in a single 
> xyplot? I'd like to stick to the lattice package, since this package has 
> more layout possibilities over the traditional plotting functions in R.

  I don't know about dynamically determining the number of lines, but
the following gives different colors for each line automatically:

library(lattice)
df <- data.frame(a = runif(10), b = runif(10), c = runif(10), x = 1:10)
xyplot(a + b + c ~ x, data = df, type = "l", auto.key=TRUE)

> cheers,
> Bram
> 
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> 

-- 
Chuck Cleland, Ph.D.
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