R - Fill in data gaps function

fillNAgaps <- function(x, firstBack=FALSE) {
  ## NA's in a vector or factor are replaced with last non-NA values
  ## If firstBack is TRUE, it will fill in leading NA's with the first
  ## non-NA value. If FALSE, it will not change leading NA's.
 
  # If it's a factor, store the level labels and convert to integer
  lvls <- NULL
  if (is.factor(x)) {
    lvls <- levels(x)
    x    <- as.integer(x)
  }
 
  goodIdx <- !is.na(x)
 
  # These are the non-NA values from x only
  # Add a leading NA or take the first good value, depending on firstBack 
  if (firstBack)   goodVals <- c(x[goodIdx][1], x[goodIdx])
  else             goodVals <- c(NA,            x[goodIdx])
 
  # Fill the indices of the output vector with the indices pulled from
  # these offsets of goodVals. Add 1 to avoid indexing to zero.
  fillIdx <- cumsum(goodIdx)+1
 
  x <- goodVals[fillIdx]
 
  # If it was originally a factor, convert it back
  if (!is.null(lvls)) {
    x <- factor(x, levels=seq_along(lvls), labels=lvls)
  }
 
  x
}

colInput <-c(2,4,5,6,1,8,9,3,10,13,11,12)
bins <-5
colInput<-sort(colInput)

colOutput <- c()
n<- seq(1,length(colInput),by = length(colInput)/bins)

for (i in 1:length(n)){
  if(i <= n[i]){
    colOutput[ceiling(n[i]):ceiling(n[i]+1)] <-  paste("group " ,toString(i))
    if(is.na(colOutput[floor(n[i])])){colOutput[floor(n[i])]<-paste("group " ,toString(i))}
  }
}

colInput<-sort(colInput)

colOutput<-colOutput[1:length(colInput)]

colOutput<-fillNAgaps(colOutput)

tblNewGroup <- cbind(colInput ,colOutput)