R/mpc.R

In zcebeci/fcvalid: Internal Validity Indexes for Fuzzy and Possibilistic Clustering

mpc <- function(u, m, t=NULL, eta=NULL, tidx="f"){
  if(missing(u))
    stop("Missing input membership matrix or ppclust object")
  tidx <- match.arg(tidx, c("e","f","g"))
  if(inherits(u, "ppclust")){
    if(!is.null(u$u)){
      U <- as.matrix(u$u)
      m <- u$m
    }
    else if(!is.null(u$t)){
      U <- as.matrix(u$t)
      m <- u$eta
    }
    else{
      stop("Missing fuzzy membership or typicality matrix")
    }
    if(tidx == "e" || tidx == "g"){
      if(!is.null(u$t)){
        T <- u$t
        eta <- u$eta
      }
      else
        stop("Input argument is ppclust object but does not have the typicality matrix")
    }
  }
  else{
    if(is.matrix(u) || is.data.frame(u))
      U <- as.matrix(u)
    else
      stop("Argument 'u' must be a numeric data frame or matrix")
    if(!is.null(t) && tidx != "f")
      if(is.matrix(t) || is.data.frame(t))
        T <- as.matrix(t)
      else
        stop("Argument 't' must be a numeric data frame or matrix")
    if(missing(m))
      m <- 2 
    if(!is.numeric(m))
      stop("Argument 'm' must be number") 
    if(m < 1)
      stop("Argument 'm' should be a positive number equals to or greater than 1") 
    if(missing(eta))
      eta <- 2 
    if(!is.numeric(eta))
      stop("Argument 'eta' must be number") 
    if(eta < 1)
      stop("Argument 'eta' should be a positive number equals to or greater than 1") 
  }
  if(tidx == "g"){
    if(!is.null(T))
      U <- T/rowSums(T)
    else
      stop("The typicality matrix is required to compute the generalized Dave (MPC) index")
  }
  if(tidx == "e")
    idx <- 1-(ncol(U)/(ncol(U)-1))*(1-1/(sum((U)^m+(T)^eta)/(nrow(U)/2)))
  else
    idx <- 1-(ncol(U)/(ncol(U)-1))*(1-sum((U)^m)/nrow(U))
  if(tidx == "f")
    names(idx) <- "mpc"
  else if(tidx == "e")
    names(idx) <- "mpc.e"
  else if(tidx == "g")
    names(idx) <- "mpc.g"
  return(idx)
}