[R] limit bar graph output

[Jeff Reichman]

R-Help Forum

I'm using the following code to reorder (from highest to lowest) my miRNA
counts.  But there are 500 plus and I only need the first (say) 15-20.  How
do I limit ggplot to only the first 20 miRNA counts

ggplot(data = corr.m, aes(x = reorder(miRNA, -value), y = value, fill =
variable)) + 
  geom_bar(stat = "identity")

Jeff