如何修复以下代码
alpha <- 1
draws <- 15
dimen <- 10
require(MCMCpack)
x <- rdirichlet(draws, rep(alpha, dimen))
require(ggplot2)
dat <- data.frame(item=factor(rep(1:10,15)),
draw=factor(rep(1:15,each=10)),
value=as.vector(t(x)))
ggplot(dat,aes(x=item,y=value,ymin=0,ymax=value)) +
geom_point(colour=I("blue")) +
geom_linerange(colour=I("blue")) +
facet_wrap(~draw,ncol=5) +
scale_y_continuous(lim=c(0,1)) +
opts(panel.border=theme_rect())
不要得到这个空的情节: