cops-package {cops}R Documentation

cops: cluster optimized proximity scaling

Description

About the package cops: Cluster optimized proximity scaling (COPS) refers to multidimensional scaling methods that aim at pronouncing the clustered appearance of the configuration. They achieve this by transforming proximities/distances with power functions and augment the fitting criterion with a clusteredness index, the OPTICS Cordillera (Rusch, Hornik & Mair 2018). There are two variants: One for finding the configuration directly for given parameters (COPS-C), and one for using the augmented fitting criterion to find optimal parameters for the power transformations (P-COPS). The package contains various functions, wrappers, methods and classes for fitting, plotting and displaying different MDS models in a COPS framework like Torgerson scaling, SMACOF, Sammon mapping, elastic scaling, symmetric SMACOF, spherical SMACOF, sstress, rstress, powermds, power elastic scaling, power sammon mapping, powerstress. All of these models can also solely be fit as MDS with power transformations. The package further contains functions for optimization (Adaptive LJ Algorithmus).

Details

The cops package provides five categories of important functions:

Models & Algorithms:

Optimization functions:

Wrappers and convenience functions:

Methods: For most of the objects returned by the high-level functions S3 classes and methods for standard generics were implemented, including print, summary, plot, plot3dstatic.

References:

Author(s)

Maintainer: Thomas Rusch thomas.rusch@wu.ac.at (ORCID)

Authors:

Other contributors:

See Also

Useful links:

Examples


data(BankingCrisesDistances)


# shorthand function for COPS-C (finding configuration with copstress)
res<-cops(BankingCrisesDistances[,1:69],variant="COPS-C",
          stressweight=0.98,cordweight=0.02,itmax=1000)
# Note: itmax is very small here for illustration; will give a non-convergence
# warning of the optimizer which disappears at itmax=275000  

res
summary(res)
plot(res)
plot(res,"reachplot")
plot(res,"transplot")
plot(res,"Shepard")
#shorthand function for P-COPS (hyperparameter search for powerstress)
res<-cops(BankingCrisesDistances[,1:69],variant="P-COPS")
res
summary(res)
plot(res)
plot(res,"reachplot")
plot(res,"transplot")
plot(res,"Shepard")


[Package cops version 1.12-1 Index]