[R] Adding locfit confidence intervals in trelis xyplot

[Deepayan Sarkar]

On 10/19/06, juan f poyatos <jpoyatos at cnio.es> wrote:
>
> But it is *within* a trellis plot when I cannot plot the bands!
>
> Building up on Dieter's example:
>
> x <- rnorm(100)
> y <- dnorm(x) + rnorm(100) / 5
> plot(locfit(y~x), band="global")
>
> Plots two nice confidence bands.
>
> But try this
> z <- dnorm(y) + rnorm(100) / 3
> Z <- equal.count(z, number = 4, overlap = .1)
> xyplot(z ~ y|Z, alpha = 1,band = "global",panel = panel.locfit)
>
> and you will not see the bands,
>
> indeed band is completely ignored as
> xyplot(z ~ y|Z, alpha = 1,band = "rubbish",panel = panel.locfit)
>
> works fine but without the bands!!

And why does that come as a surprise to you?

Since you seem to have missed the point of the previous replies, let
me spell it out for you. A function does what it is instructed to do,
not what you _want_ it to do. The most reliable way to figure out what
those instructions are is to look at the source code of that function.
Since this is not very user friendly, R also requires that all
functions be documented, and specifically, that the documentation for
any function, say foo, can be accessed by typing help(foo). Since you
are using the function panel.locfit, you are supposed to look at
help(panel.locfit), which does not claim to have any support for
bands.

In this case, the source of panel.locfit is actually simpler:

panel.locfit
function (x, y, subscripts, z, xyz.labs, xyz.axes, xyz.mid, xyz.minmax,
    xyz.range, col.regions, at, drape, contour, region, groups,
    ...)
{
       panel.xyplot(x, y, ...)
        args <- list(x = x, y = y, ...)
        ok <- names(formals(locfit.raw))
        llines.locfit(do.call("locfit.raw", args[ok[ok %in% names(args)]]))
}

(removing the irrelevant part)

-Deepayan

>
> - juan
>
>
> On Thu, 2006-10-19 at 07:49 +0000, Dieter Menne wrote:
> > Deepayan Sarkar <deepayan.sarkar <at> gmail.com> writes:
> >
> > >
> > > On 10/18/06, juan f poyatos <jpoyatos <at> cnio.es> wrote:
> > > > Dear all,
> > > > I am trying to include confidence intervals in a xyplot.
> > > >
> > ...
> >
> > > Well, panel.locfit doesn't have any options to draw confidence bands,
> > > so you'll have to write a panel function that does. Shouldn't be hard
> > > to extend panel.locfit if you know how to extract that information
> > > from a locfit object.
> >
> > plot.locfit has bands. I think Juan mixed trellis and standard plot
> > documentation.
> >
> >
> > x <- rnorm(100)
> > y <- dnorm(x) + rnorm(100) / 5
> > plot(locfit(y~x), band="global")
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> --
> Juan F. Poyatos
> Structural and Computational Biology Programme
> Spanish National Cancer Centre (CNIO)
> Melchor Fernandez Almagro, 3/E-28029 Madrid SPAIN
> Phone:+34 912 246 900/Fax: +34 912 246 980
>
> http://bioinfo.cnio.es/~jpoyatos/
>
>
>
>
> **NOTA DE CONFIDENCIALIDAD** Este correo electrónico, y en s...{{dropped}}
>
>
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
>


-- 
http://www.stat.wisc.edu/~deepayan/