# [R] Use of colour in plots

Petr PIKAL petr.pikal at precheza.cz
Fri Sep 5 16:40:47 CEST 2008

```Hi

r-help-bounces at r-project.org napsal dne 05.09.2008 16:24:35:

> Here is an example doing the same type of thing.
> It should be easy enough to adapt.
>
> Good luck
>
> ===========================================================
> x <- runif(100, 0, 1)
> y <- runif(100, 0, 1)
> z <- data.frame(x,y)
>
>  plot(subset(z, z\$y >=.5), col="red", ylim=c(min(z\$y),
>  max(z\$y)), pch=16)
>  points(subset(z, z\$y <=.49), col="blue", pch=16)
> ===========================================================

Or

third <- (z\$y >=.5)+1
plot(z, col=third, pch=16)

Just tell to col a vector of colors with appropriate use of logical.

Or you can use col = as.numeric(some factor), which is quite convenient
use of factors feature which is not desired in other cases.
See warning section of factor help page.

Regards

>
>
> --- On Fri, 9/5/08, Steve Murray <smurray444 at hotmail.com> wrote:
>
> > From: Steve Murray <smurray444 at hotmail.com>
> > Subject: [R] Use of colour in plots
> > To: r-help at r-project.org
> > Received: Friday, September 5, 2008, 9:10 AM
> > Dear all,
> >
> > I have 3 datasets all of which share the same longitude and
> > latitude values, which I'm looking to plot onto a
> > scattergraph. The third dataset has values which can only be
> > either '1' or '2'. So to incorporate all
> > three datasets onto two axes, I'm wondering if I can
> > plot dataset1 and dataset2 as normal, but then use colour to
> > determine whether these points are either values '1'
> > or '2' according to the third dataset.
> >
> > If so, how would I go about doing this in R, and what
> > format would the command take?
> >
> > Thanks for any help offered,
> >
> > Steve
> >
> > ______________________________________________
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> > reproducible code.
>
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