"headtail" <- 
function(x, hlength=4,tlength=4,digits=2) {
  if(is.data.frame(x) | is.matrix(x) ) { if (is.matrix(x)) x <- data.frame(unclass(x))
  nvar <- dim(x)[2]
  ellipsis <- rep("...",nvar)
   h <- data.frame(head(x,hlength))
   t <- data.frame(tail(x,tlength))
 for (i in 1:nvar) {
    if(is.numeric(h[1,i])) {h[i] <- round(h[i],digits)
                         t[i] <- round(t[i],digits)
                         } else {ellipsis[i] <- NA}
     } 
  
   head.tail <- rbind(h,... =  ellipsis,t)
   } else {h <- head(x,hlength)
           t <- tail(x,tlength)
           head.tail <- rbind(h,"...       ...",t)}  
   return(head.tail)}
 #revised Feb 1, 2010
 #revised August 10, 2011 to work with mixed numeric and non-numeric data