[R] attempt at making a polygon class failed
Uwe Ligges
ligges at statistik.uni-dortmund.de
Wed Aug 29 10:11:26 CEST 2007
Leeds, Mark (IED) wrote:
> I was reading a presentation of Professor Peng's and typed the
> presentation code into R but I changed it to make plot.polygon a
> separate function instread of defining the function in SetMethod itself
> as he did. Is that the problem with the code below because
> plot(p) just gives me zero. Thanks.
>
>
> setClass("polygon", representation(x = "numeric",
> y = "numeric"))
>
> plot <- function(object)
> {
> return(0)
> }
If you redefine plot this way, you cannot use a call to the generic plot
within the plot.polygon function any more.
Hence do *not* define the new plot() function above. The rest should work.
Uwe Ligges
> setGeneric("plot")
>
> plot.polygon <- function(x, y, ...) {
> xlim <- range(x at x)
> ylim <- range(x at y)
> plot(0,0, type = "n", xlim = xlim, ylim = ylim, ...)
> xp <- c(x at x, x at x[1])
> yp <- c(x at y, x at y[1])
> lines(xp, yp)
> }
>
> setMethod("plot","polygon",plot.polygon)
>
> p <- new("polygon", x = c(1,2,3,4), y = c(1,2,3,1))
>
> plot(p)
> --------------------------------------------------------
>
> This is not an offer (or solicitation of an offer) to buy/se...{{dropped}}
>
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