cop_sstress: PCOPS version of sstress

Description

Free parameter is lambda for the observed proximities. Fitted distances are transformed with power 2, weights have exponent of 1. Note that the lambda here works as a multiplicator of 2 (as sstress has f(delta^2)).

Usage

cop_sstress(
  dis,
  theta = c(2, 1, 1),
  weightmat = 1 - diag(nrow(dis)),
  init = NULL,
  ndim = 2,
  itmaxi = 10000,
  ...,
  stressweight = 1,
  cordweight = 0.5,
  q = 1,
  minpts = ndim + 1,
  epsilon = 10,
  rang = NULL,
  verbose = 0,
  scale = "sd",
  normed = TRUE,
  stresstype = c("default", "stress1", "rawstress", "normstress", "enormstress",
    "enormstress1")
)

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
cordillera: the cordillera object

Arguments

dis: numeric matrix or dist object of a matrix of proximities
theta: the theta vector of powers; this must be a scalar of the lambda transformation for the observed proximities. Defaults to 1. Note that the lambda here works as a multiplicator of 2 (as sstress has f(delta^2)).
weightmat: (optional) a matrix of nonnegative weights
init: (optional) initial configuration
ndim: number of dimensions of the target space
itmaxi: number of iterations. default is 10000.
...: 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
scale: should the configuration be scale adjusted
normed: should the cordillera be normed; defaults to TRUE
stresstype: which stress to report? Defaults to explicitly normed stress