Followup: Re: [R] Interaction Plots in R

[Ko-Kang Wang]

Ah yes.  I've just tested the code and it proved to be extremely good.  Thank you.

I actually think it will be a good idea to put up a package (library), with
examples and help files etc...I don't know how the others on this list think about
this idea, but I would certainly like to see such a package in CRAN.

If you don't mind, I could put up a package for you and e-mailed it to you.

Thanks again.

Ko-Kang

Kaspar Pflugshaupt wrote:

> >>
> >> Ko-Kang Wang wrote:
> >> Is there a function to do interaction plots in R?
> >> I know in Splus I can simply use interaction.plot()
> >
> > Thanks.
> > I don't think there's such a function, so I wrote one some time ago. It takes
> > two factors f1, f2 and a response variable data.
>
> Well, I've been using that function a lot lately and so I've improved it
> considerably, up to the point of being useful. Having a bit of a bad
> conscience for my last version (it was rather ugly), I'd like to post a
> better one. It uses colours, draws a legend (which can be reordered) and
> does a better job with axis labels. What's more, I've since discovered the
> "matlines" function :-) .
>
> If anyone else needs interaction plots similar to S-Plus, here you go:
>
> ----------------------------------------------------------
> interaction.plot<-
> function (f1, f2, data, main = "Interaction Plot",
>     xlab = deparse(substitute(f2)),
>     ylab = paste("Mean of", deparse(substitute(data))),
>     legend=T, leg.order = 1:n1, ...)
> {
>
>     # f1,f2: factors. data: data vector
>     # (extraction from matrix or data.frame not implemented)
>
>     cellmeans <- tapply(data, list(f1, f2), mean)
>     n1 <- nlevels(f1)
>     n2 <- nlevels(f2)
>     xr <- c(1, n2)
>     yr <- range(cellmeans)
>     plot(0, 0, type = "n", xaxt = "n", xlim = xr, ylim = yr,
>         main = main, xlab = xlab, ylab = ylab)
>     matlines(t(cellmeans), lty = 1, col = 1:n1)
>     axis(1, at = 1:n2, labels = as.character(levels(f2)))
>     if(legend)
>         legend(locator(1), legend = rownames(cellmeans)[leg.order],
>             lty = 1, col = (1:n1)[leg.order])
>
>     # locator(1) waits for user to choose legend location
>     # (click marks upper left corner)
>     # legend entries get ordered according to leg.order
>
>     invisible(list(cellmeans = cellmeans))
>     # cellmeans are returned
> }
> --------------------------------------------------------
>
>  --
> Kaspar Pflugshaupt
> Geobotanisches Institut ETH Zurich
> mailto: pflugshaupt at geobot.umnw.ethz.ch
>
> --
>
> Kaspar Pflugshaupt
> Geobotanisches Institut
> Zuerichbergstr. 38
> CH-8044 Zuerich
>
> Tel. ++41 1 632 43 19
> Fax  ++41 1 632 12 15
>
> mailto:pflugshaupt at geobot.umnw.ethz.ch
> privat:pflugshaupt at mails.ch
> http://www.geobot.umnw.ethz.ch
>
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--
-----------------------------------------------------------------------------------

 Ko-Kang Wang
 Undergraduate Student
 Computer Science/Statistics Double Major
 University of Auckland
 Auckland 1005
 New Zealand
-----------------------------------------------------------------------------------



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