[R] Scatterplot with the 3rd dimension = color?

[Kerry]

Yes, the qplot works great, but do you know how to allow for multiple
plots? I want one variable to be plotted say from blue to red and
another say from yellow to green but in the same graph, each having
there own separate legends. I've tried print() and arrange() but no
luck.

Thanks again,
kb

On Oct 2, 10:42 pm, Ben Bolker <bbol... at gmail.com> wrote:
> Duncan Murdoch <murdoch.duncan <at> gmail.com> writes:
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> > On 11-10-02 1:11 PM, Kerry wrote:
> > > I have 3 columns of data and want to plot each row as a point in a
> > > scatter plot and want one column to be represented as a color gradient
> > > (e.g. larger  values being more red). Anyone know the command or
> > > package for this?
>
> > It's not a particularly effective display, but here's how to do it.  Use
> > rainbow(101) in place of rev(heat.colors(101)) if you like.
>
> > x <- rnorm(10)
> > y <- rnorm(10)
> > z <- rnorm(10)
> > colors <- rev(heat.colors(101))
> > zcolor <- colors[(z - min(z))/diff(range(z))*100 + 1]
> > plot(x,y,col=zcolor)
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>   or
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> d <- data.frame(x,y,z)
> library(ggplot2)
> qplot(x,y,colour=z,data=d)
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>   I agree about the "not particularly effective display"
> comment, but if you have two continuous predictors and
> a continuous response you've got a tough display problem --
> your choices are:
>
>   1. use color, size, or some other graphical characteristic
> (pretty far down on the "Cleveland hierarchy")
>   2. use a perspective plot (hard to get the right viewing
> angle, often confusing)
>   3. use coplots/small multiples/faceting (requires
> discretizing one dimension)
>
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