margination {truecluster}R Documentation

Margin combinations

Description

Functions to calculate the number of possible groupings given fixed group sizes (margins).

Usage

nlabelation(...)
lnlabelation(...)
ldlabelation(...)
nmargination(...)
lnmargination(...)
ldmargination(...)

Arguments

... one or more vectors of group sizes

Details

Function nmargination gives the number of possibles groupings (=cluster solutions) that have the input group sizes. Function nlabelation gives the number of possibles assignents to predefined (=labelled) groups of the requires sizes (more possibilities). The ln-versions give the log instead, the ld-versions the logarithm dualis.

Value

scalar

Author(s)

Jens Oehlschlägel

See Also

clusteration, permutation, combination, choose, lgamma, absolute.entropy, exact.margin.info

Examples

  cat("There are 25 possibilities to make 3 clusters from 5 cases\n")
  nclusteration(5,3)
  cat(" 10 of sizes 3,1,1\n")
  nmargination(3,1,1)
  cat(" and 15 of sizes 2,2,1\n")
  nmargination(2,2,1)
  cat("By contrast there are 30 possibilities to assign 5 cases to 3 labelled groups a=2,b=2,c=1\n")
  nlabelation(2,2,1)
  n <- 250
  k <- 5
  i <- 1:(n/k)
  matplot(k*i, cbind(
      k^(i*k)
    , sapply(i, function(i){nclusteration(k*i, k)})
    , sapply(i, function(i){nmargination(rep(i, k))})
    )
  , log="y", type="l"
  , lty=1:3, xlab="n"
  , ylab = "combinations"
  , main = "number of possible groupings"
  )
  legend(n,1
  , c(substitute(k^n, list(k=k)), expression("no restriction"), expression("equal sizes"))
  , lty=1:3, col=1:3, xjust=1, yjust=0
  )

[Package truecluster version 0.3 Index]