[R] setting specific colours for different groups of points on a scatter plot

[Petr PIKAL]

Hi

if you do not insist on lattice you can

plot(a~b, col = c+1) or if you do not like built colours

mycol <- c("blue", "red", "green", "whatever")
plot(a~b, col = mycol[c+1])

Petr Pikal
petr.pikal at precheza.cz
724008364, 581252140, 581252257


r-help-bounces at r-project.org napsal dne 22.05.2008 21:04:02:

> On 5/22/08, Sarah Kinnings <bssk at leeds.ac.uk> wrote:
> > Hi,
> >
> >  I have a table with three columns of data, let's call these a, b and 
c. I
> > have produced a scatter plot of a against b, but I would like to 
colour the
> > points according to their corresponding c values. c takes the value of
> > either 0,1,2,3 or 4 and so I would like to colour all of the points 
with a c
> > value of 0 one colour, all those with a c value of 1 another colour 
etc.
> > When I use the following code, it colours the points using default 
colours,
> > which are not suitable:
> >
> >  data<-read.table('abc',header=T, sep="\t")
> >  attach(data)
> >  library(lattice)
> >  xyplot(a~b, col=c)
> >
> >  I was therefore wondering how to specify my own set of colours for 
each of
> > the c values. Any help would really be appreciated as I have spent 
ages
> > reading through the documentation, but with no luck.
> 
> The recommended way would be
> 
> mydata<-read.table('abc',header=T, sep="\t") # don't attach
> library(lattice)
> xyplot(a~b, data = mydata, groups=c)
> 
> This would use the default lattice colors (which should be different
> from the ones you saw). If you don't like them, you could specify your
> own colors with
> 
> mycol <- c("blue", "red", "green", "whatever")
> xyplot(a~b, data = mydata, groups=c, col = mycol)
> 
> You will probably end up wanting a legend, in which case a better 
approach is
> 
> xyplot(a~b, data = mydata, groups=c,
>        par.settings = simpleTheme(col = mycol),
>        auto.key = TRUE)
> 
> -Deepayan
> 
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