[R] Contents of R-help digest.-contouring

[Tony Plate]

The 'z' argument to contour must be a matrix with the appropriate 
dimensions -- lo.2 as defined originally has dimensions 4356 by 1.

You can create a matrix of appropriate dimensions as follows:

 > lo.2 <- array(lo.1$fit, dim=sapply(topo.mar, length))

It's also probably worth changing topo.mar so that the x and y elements 
have different lengths, to provide a quick check that the x and y 
dimensions were not swapped somewhere along the way.

hope this helps,

Tony Plate

At Monday 01:45 PM 7/21/2003 -0400, john lewis wrote:
>R- Users:
>
>Can someone indicate what I am during wrong? This is a script essentially 
>from
>
>Venerable & Ripley's text on interpolating a surface with loess function 
>but I can not get it to run.
>
>Thanks.
>
>John Lewis
>
>Professor
>
>McGill University
>
>Montreal
>
>
>
>library(MASS)
>
>library(modreg)
>
>data(topo)
>
>par(mfcol=c(2,2), pty="s")
>
>topo.loess <- loess(z ~ x * y, topo, degree=2, span = 0.25, normalize=F)
>
>topo.mar <- list(x = seq(0, 6.5, 0.1), y=seq(0, 6.5, 0.1))
>
>topo.lo <- predict(topo.loess, expand.grid(topo.mar), se=T)
>
>lo.1 <- as.data.frame(topo.lo)
>
>lo.2 <- as.matrix(lo.1$fit)
>
>lo.3 <- as.matrix(lo.1$se.fit)
>
>contour(topo.mar$x,topo.mar$y,lo.2, levels = seq(700,1000,25),
>
>         xlab="fit", ylab="")
>
>points(topo)
>
>contour(topo.mar$x,topo.mar$y,lo.3, levels = seq(5, 25, 5),
>
>         xlab="standard error", ylab="")
>
>title("Loess degree = 2")
>
>points(topo)
>
>
>This is the error I keep getting.
>
>"Error in contour.default(topo.mar$x, topo.mar$y, lo.2, levels = seq(700,  :
>         no proper `z' matrix specified"
>
>I received this same message when I ran the script first without changing 
>topo.lo
>from a list to data.frame etc. as seen below.
>
>contour(topo.mar$x,topo.mar$y,topo.lo$fit, levels = seq(700,1000,25),
>
>         xlab="fit", ylab="")
>
>
>I checked the length of each variable and they are correct.
>         [[alternative HTML version deleted]]
>
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Tony Plate   tplate at acm.org