[R] how to apply a panel function to each of several data series plotted on the same graph in lattice

[Deepayan Sarkar]

On Fri, Jun 18, 2010 at 5:19 PM, David Wyllie <David.Wyllie at ndm.ox.ac.uk> wrote:
> Hi
>
> Thanks, but maybe I'm not making myself clear enough here.
> I think I'm already doing what you suggest, below the line # plot with fits .. in the original mail.
>
> I have made a little progress.  I wish to apply a panel function to each of a,b,and c.
> When plotting
> xyplot(a + b + c ~ x, type = 'l'),
> in the below example the 'x' passed to the panel function is a numeric vector of 300 length, with no way of telling whether the data came from a,b, or c.
>
> I have found a discussion here
> http://www.mail-archive.com/r-help@stat.math.ethz.ch/msg94720.html
> which is helpful.
>
> One can view the same data in a 'long format' where the property of being 'a' 'b' or 'c' is in a third column, 'grp'.
>
> ## code example starts here
>
> # i.e instead of generate mock data; this comprises three data series, a,b,c with means of about 5,35, and 105.
> test <- data.frame(
> a = runif(100, min=0, max=10),
> b = 30+runif(100, min=0, max=10),
> c = 100+runif(100, min=0, max=10),
> x = 1:100)
>
> # we do  one can have the data in three columns,
> # we arrange long so we can use groups and superpose
> test2a<-data.frame (
> y=runif(100, min=0, max=10), x=1:100, grp=rep('a',100))
> test2b<-data.frame (
> y=30+runif(100, min=0, max=10), x=1:100, grp=rep('b',100))
> test2c<-data.frame (
> y=100+runif(100, min=0, max=10), x=1:100, grp=rep('c',100))
> test2<-rbind(test2a, test2b, test2c)
>
> library(lattice)
> # illustrate data the former way
> xyplot(a + b + c ~ x, data = test, type = "p", auto.key=TRUE)
>
> # or equivalently
> xyplot(y~ x|grp, data = test2, type = "p", auto.key=TRUE)
> ## now the problem, which is to fit trends through the data
> # the latter way, one can as described do http://www.mail-archive.com/r-help@stat.math.ethz.ch/msg94539.html
> xyplot(y~x, groups=grp,data=test2,
>       type='l',
>       panel = panel.superpose,
>       panel.groups = function(x, y, ..., lty) {
>               panel.xyplot(x, y, ..., lty = lty)
>               panel.abline(h = mean(y), lty=3, ...)
>  }
> )
> # and this succeeds.  however, when we then use the panel function
> # Deepayan Sarkar code from: http://www.mail-archive.com/r-help@r-project.org/msg39654.html
>  panel.smooth.spline <- function(x, y,
>            w=NULL, df, spar = NULL, cv = FALSE,
>            lwd=plot.line$lwd, lty=plot.line$lty,col, col.line=plot.line$col,
>            type, horizontal=FALSE,... )
> {
>       x <- as.numeric(x)
>          y <- as.numeric(y)
>
>          ok <- is.finite(x) & is.finite(y)
>
>          if (sum(ok) < 1)
>              return()
>          if (!missing(col)) {
>              if (missing(col.line))
>                  col.line <- col
>          }
>          plot.line <- trellis.par.get("plot.line")
>          if (horizontal) {
>              spline <-
>                  smooth.spline(y[ok], x[ok],
>                                w=w, df=df, spar = spar, cv = cv, ...)
>              panel.lines(x = spline$y, y = spline$x, col = col.line,
>                  lty = lty, lwd = lwd, ...)
>          }
>          else {
>              spline <-
>                  smooth.spline(x[ok], y[ok],
>                                w=w, df=df, spar = spar, cv = cv, ...)
>              panel.lines(x = spline$x, y = spline$y, col = col.line,
>                  lty = lty, lwd = lwd, ...)
>          }
>      }
>
>
> # and try
> xyplot(y~x, groups=grp,data=test2,
>       type='l',
>       panel = panel.superpose,
>       panel.groups = function(x, y, ..., lty) {
>               panel.xyplot(x, y, ..., lty = lty)
>               panel.smooth.spline( ...)
>  }
> )
>
> # then we generate an error 'error using packet 1', and I'm not sure why.

Actually, the complete error message is:

error using packet 1
'x' is missing

Look again carefully at your panel function. In the call to
panel.smooth.spline(...), are the 'x' and 'y' arguments supplied?

-Deepayan