specgroups {prabclus}R Documentation

Average within-group distances for given groups

Description

Generates average within-group distances (overall and group-wise) from a dissimilarity matrix and a given grouping.

Usage

  specgroups(distmat,groupvector, groupinfo) 

Arguments

distmat dissimilarity matrix or dist-object.
groupvector integer vector. For every row of distmat, a number indicating the group membership.
groupinfo list with components lg (levels of groupvector), ng (number of groups), nsg (vector of group sizes).

Value

A list with parameters

overall overall average within-groups dissimilarity.
gr vector of group-wise average within-group dissimilarities.

Author(s)

Christian Hennig chrish@stats.ucl.ac.uk http://www.homepages.ucl.ac.uk/~ucakche

Examples

  data(siskiyou)
  x <- prabinit(prabmatrix=siskiyou, neighborhood=siskiyou.nb,
              distance="logkulczynski")  
  groupvector <- as.factor(siskiyou.groups)
  ng <- length(levels(groupvector))
  lg <- levels(groupvector)
  nsg <- numeric(0)
    for (i in 1:ng) nsg[i] <- sum(groupvector==lg[i])
  groupinfo <- list(lg=lg,ng=ng,nsg=nsg)
  specgroups(x$distmat,groupvector,groupinfo)

[Package prabclus version 2.1-2 Index]