icExploreGen {smacofx}

Exploring initial configurations in an agnostic way

Description

Allows to user to explore the effect of various starting configurations when fitting an MDS model. This is a bit more general than the icExplore function in smacof, as we allow any PS model to be used as the model is either setup by call or by a prefitted object (for the models in cops and stops we do not have a single UI function which necessitates this). Additionally, one can supply their own configurations and not just random ones.

Usage

icExploreGen(
  object,
  mdscall = NULL,
  conflist,
  nrep = 100,
  ndim,
  returnfit = FALSE,
  min = -5,
  max = 5,
  verbose = FALSE
)

Arguments

object

A fitted object of class 'smacofP', 'smacofB' or 'smacof'. If supplied this takes precedence over the call argument. If given this is added to the output and may be the optimal one.

mdscall

Alternatively to a fitted object, one can pass a syntactically valid call for any of the MDS functions cops, stops or smacof that find a configuration (not the ones that do parameter selection like pcops or stops). If object and call is given, object takes precedence.

conflist

Optional list of starting configurations.

nrep

If conflist is not supplied, how many random starting configurations should be used.

ndim

Dimensions of target space.

returnfit

Should all fitted MDS be returned. If FALSE (default) none is returned.

min

lower bound for the uniform distribution to sample from

max

upper bound for the uniform distribution to sample from

verbose

If >0 prints the fitting progress.

Details

If no configuration list is supplied, then nrep configurations are simulated. They are drawn from a ndim-dimensional uniform distribution with minimum min and maximum max. We recommend to use the route via supplying a fitted model as these are typically starting from a Torgerson configuration and are likely quite good.

Value

an object of class 'icexplore', see icExplore for more. There is a plot method in package 'smacof'.

Examples

dis<-smacof::kinshipdelta

## Version 1: Using a fitted object (recommended)
res1<-rStressMin(delta=dis,type="ordinal",itmax=100)
resm<-icExploreGen(res1,nrep=5)

## Version 2: Using a call object and supplying conflist
conflist<-list(res1$init,jitter(res1$init,1),jitter(res1$init,1),jitter(res1$init,1))
c1 <- call("smds",delta=dis,tau=0.2,itmax=100)
resm<-icExploreGen(mdscall=c1,conflist=conflist,returnfit=TRUE)

plot(resm)