[R] A plot of factor data?

[Sang Chul Choi]

Hi,

I am wondering if there is a way to plot proportions of factors. I  
tried to find plot functions for those but in vain.

For example, I have a data like this where column "a" has 10 of "0"s  
and 15 of "1"s, and column "b" has 5 and 20.

 > x <- 
data 
.frame 
("a"=factor(c(rep(0,10),rep(1,15))),b=factor(c(rep(0,5),rep(1,20))))
 > summary(x)
  a      b
  0:10   0: 5
  1:15   1:20

I want to have a plot like:

|-----|
|     |     <--- proportion of "0"
|     |
|-----|
|     |
|     |     <--- proportion of "1"
|     |
|-----|

column "a"

|-----|
|     |     <--- proportion of "0"
|-----|
|     |
|     |
|     |     <--- proportion of "1"
|     |
|-----|

column "b"

Is there anybody who can do this easily? I appreciate any help.

Thank you,

Sang Chul