alscal: ALSCAL - MDS via S-Stress Minimization

In smacofx: Flexible Multidimensional Scaling and 'smacof' Extensions

ALSCAL - MDS via S-Stress Minimization

Description

An implementation to minimize s-stress by majorization with ratio and interval optimal scaling.

Usage

alscal(
  delta,
  type = "ratio",
  weightmat,
  init = NULL,
  ndim = 2,
  acc = 1e-06,
  itmax = 10000,
  verbose = FALSE,
  principal = FALSE
)

Arguments

delta	dist object or a symmetric, numeric data.frame or matrix of distances
type	what type of MDS to fit. Currently one of "ratio" or "interval". Default is "ratio".
weightmat	a matrix of finite weights
init	starting configuration
ndim	dimension of the configuration; defaults to 2
acc	numeric accuracy of the iteration. Default is 1e-6.
itmax	maximum number of iterations. Default is 10000.
verbose	should iteration information been given; if > 0 then yes
principal	If ‘TRUE’, principal axis transformation is applied to the final configuration

Value

a 'smacofP' object (inheriting from 'smacofB', see smacofSym). It is a list with the components

• delta: Observed untransformed dissimilarities

• tdelta: Observed explicitly transformed (squared) dissimilarities, normalized

• dhat: Explicitly transformed dissimilarities (dhats), optimally scaled and normalized

• confdist: Transformed configuration distances

• conf: Matrix of fitted configuration

• stress: Default stress (stress 1; sqrt of explicitly normalized stress)

• spp: Stress per point

• ndim: Number of dimensions

• model: Name of smacof model

• niter: Number of iterations

• nobj: Number of objects

• type: Type of MDS model

• weightmat: weighting matrix as supplied

• stress.m: Default stress (stress-1^2)

• tweightmat: transformed weighting matrix (here NULL)

See Also

rStressMin

Examples

dis<-smacof::kinshipdelta
res<-alscal(as.matrix(dis),type="interval",itmax=1000)
res
summary(res)
plot(res)

smacofx documentation built on Aug. 8, 2025, 6:28 p.m.