MASS: isoMDS and sammon

Peter Kleiweg <kleiweg@let.rug.nl> writes:

If tbl is an object of class 'dist', you can do this:

    a <- sammon(tbl, k=3)


But you can't do this:

    b <- isoMDS(tbl, k=3)


Wouldn't it be sensible to have identical interfaces to sammon()
and isoMDS() ?

I think all that would be needed is to change this:

  isoMDS <- function(d, y=cmdscale(d, 2), maxit=50, trace=TRUE)
  {

...into this:

  isoMDS <- function(d, y, k=2, maxit=50, trace=TRUE)
  {
    if(missing(y)) y <- cmdscale(d, k=k)

Actually, it should work if you simply define the arguments as

isoMDS <- function(d, y=cmdscale(d, k), k=2, maxit=50, trace=TRUE)

Default arguments can refer to each other and even to items calculated
inside the function.