R/adjustedRandIndex.R

In deepgmm: Deep Gaussian Mixture Models

adjustedRandIndex=function (x, y) 
{
  x <- as.vector(x)
  y <- as.vector(y)
  if (length(x) != length(y)) 
    stop("arguments must be vectors of the same length")
  tab <- table(x, y)
  if (all(dim(tab) == c(1, 1))) 
    return(1)
  a <- sum(choose(tab, 2))
  b <- sum(choose(rowSums(tab), 2)) - a
  c <- sum(choose(colSums(tab), 2)) - a
  d <- choose(sum(tab), 2) - a - b - c
  ARI <- (a - (a + b) * (a + c)/(a + b + c + d))/((a + b + 
                                                     a + c)/2 - (a + b) * (a + c)/(a + b + c + d))
  return(ARI)
}