kaneplusplus / biganalytics Goto Github PK

getcenters <- function(x, k, nstart) {
  x <- x[!duplicated(as.matrix(x)), ];

  n <- nrow(x);
  if (n<k) {
    stop("not enough unique centers.\n");
  }

  centers <- list(x[sample(1:n, k),,drop=FALSE]);
  if (nstart>1) {
    for (i in 2:nstart) {
      centers[[length(centers)+1]] <- x[sample(1:n, k),,drop=FALSE];
    }
  }
  return(centers);
}

  #################################################
  # Check centers for sanity and consider nstart>1:
  if (is.matrix(centers)) {
    if (nstart>1) {
      stop("Only one set of starting points provided, but nstart>1.\n"))
    } else {
      if (any(duplicated(centers))) {
        stop("Error: if you provide centers, they had better not have duplicates.\n"))
      }
      centers <- list(centers)
    }
  } else if (is.list(centers)) {
    if(nstart > length(centers)) {
      stop("Not enough starting points provided.\n")
    } else {
      if(any(unlist(lapply(centers, function(x){any(duplicated(x))} )))) {
	stop("Error: if you provide centers, they had better not have duplicates.\n"))
      }
    }
  } else {
    if (is.numeric(centers) && length(centers)==1 && centers>0) {
      k <- centers
      centers <- getcenters(x, k, nstart)
    } else stop("centers must be a matrix/list of centers or number of clusters > 0")
  }