问一下大神们，boxplot画图出现这样的错误，这怎么解决

渊怨

> #两个交叉因子的箱线图
> mtcars$cyl.f<-factor(mtcars$cyl,
+                      levels = c(4,6,8),
+                      labels = c("4","6","8"))
> mtcars$am.f<-factor(mtcars$am,
+                     levels = c(0,1),
+                     labels = c("auto","standard"))
> boxplot(mpg~am.f*cyl.f,data=mtcars,
+         varwidth=TRUE,col=c("gold","darkgreen"),
+         main="MPG Disrtibution by Auto Type",
+         xlab="Auto Type")
Error in plot.window(xlim = xlim, ylim = ylim, log = log, yaxs = pars$yaxs) :
  'ylim'值不能是无限的
In addition: Warning messages:
1: In min(x) : no non-missing arguments to min; returning Inf
2: In max(x) : no non-missing arguments to max; returning -Inf