powerStressFast: Power stress minimization by NEWUOA In cops: Cluster Optimized Proximity Scaling

Description

An implementation to minimize power stress by a derivative-free trust region optimization algorithm (NEWUOA). Much faster than majorizing as used in powerStressMin but perhaps less accurate.

Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12``` ```powerStressFast( delta, kappa = 1, lambda = 1, nu = 1, weightmat = 1 - diag(nrow(delta)), init = NULL, ndim = 2, acc = 1e-12, itmax = 50000, verbose = FALSE ) ```

Arguments

 `delta` dist object or a symmetric, numeric data.frame or matrix of distances `kappa` power of the transformation of the fitted distances; defaults to 1 `lambda` the power of the transformation of the proximities; defaults to 1 `nu` the power of the transformation for weightmat; defaults to 1 `weightmat` a matrix of finite weights `init` starting configuration `ndim` dimension of the configuration; defaults to 2 `acc` The smallest value of the trust region radius that is allowed. If not defined, then 1e-10 will be used. `itmax` maximum number of iterations. Default is 50000. `verbose` should iteration output be printed; if > 1 then yes

Value

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

• delta: Observed dissimilarities, not normalized

• obsdiss: Observed dissimilarities, normalized

• confdist: Configuration dissimilarities, NOT normalized

• conf: Matrix of fitted configuration, NOT normalized

• stress: Default stress (stress 1, square root of the explicitly normalized stress on the normalized, transformed dissimilarities)

• spp: Stress per point (based on stress.en)

• ndim: Number of dimensions

• model: Name of smacof model

• niter: Number of iterations

• nobj: Number of objects

• type: Type of MDS model

• gamma: Empty

• stress.m: default stress for the COPS and STOP. Defaults to the explicitly normalized stress on the normalized, transformed dissimilarities

• stress.en: explicitly stress on the normalized, transformed dissimilarities and normalized transformed distances

• deltaorig: observed, untransformed dissimilarities

• weightmat: weighting matrix

`smacofSym`
 ```1 2 3 4 5``` ```dis<-smacof::kinshipdelta res<-powerStressFast(as.matrix(dis),kappa=2,lambda=1.5) res summary(res) plot(res) ```