cop_apstress: PCOPS version of approximated power stress model.

In cops: Cluster Optimized Proximity Scaling

PCOPS version of approximated power stress model.

Description

This uses an approximation to power stress that can make use of smacof as workhorse. Free parameters are tau and upsilon.

Usage

cop_apstress(
  dis,
  theta = c(1, 1, 1),
  ndim = 2,
  weightmat = NULL,
  init = NULL,
  itmaxi = 1000,
  ...,
  stressweight = 1,
  cordweight = 0.5,
  q = 1,
  minpts = ndim + 1,
  epsilon = 10,
  rang = NULL,
  verbose = 0,
  normed = TRUE,
  scale = "sd",
  stresstype = "default"
)

Arguments

dis	numeric matrix or dist object of a matrix of proximities
theta	the theta vector of parameters to optimize over. Must be of length two, with the first the tau argument and the second the upsilon argument. It can also be a scalar of the tau and upsilon transformation for the observed proximities and gets recycled for both ups and tau (so they are equal). Defaults to 1 1.
ndim	number of dimensions of the target space
weightmat	(optional) a binary matrix of nonnegative weights
init	(optional) initial configuration
itmaxi	number of iterations. default is 1000.
...	additional arguments to be passed to the fitting procedure
stressweight	weight to be used for the fit measure; defaults to 1
cordweight	weight to be used for the cordillera; defaults to 0.5
q	the norm of the cordillera; defaults to 1
minpts	the minimum points to make up a cluster in OPTICS; defaults to ndim+1
epsilon	the epsilon parameter of OPTICS, the neighbourhood that is checked; defaults to 10
rang	range of the distances (min distance minus max distance). If NULL (default) the cordillera will be normed to each configuration's maximum distance, so an absolute value of goodness-of-clusteredness.
verbose	numeric value hat prints information on the fitting process; >2 is extremely verbose
normed	should the cordillera be normed; defaults to TRUE
scale	should the configuration be scale adjusted
stresstype	which stress to report. Only takes smacofs default stress currrently.

Value

A list with the components

• stress: the stress

• stress.m: default normalized stress

• copstress: the weighted loss value

• OC: the Optics cordillera value

• parameters: the parameters used for fitting (kappa, lambda)

• fit: the returned object of the fitting procedure (which has all smacofB elements and some more

• cordillera: the cordillera object

cops documentation built on Jan. 22, 2023, 1:47 a.m.