r - Create barplot from data.frame

Question

In R I have a data.frame like the one on the top of the picture.

Is there a possibility to create a barplot like below?

data.frame:

      X1   X2   X3  
 --- ---- ---- ---- 
  A    2   3    4   
  B    4   2    1   
  C    1   NA   NA  

Barplot:

----------------------------
|                          |
|       #    #             |
|    #  #    #             |
| #  #  #    #  #          |
| #  #  #    #  #  #    #  |
----------------------------
  X1 X2 X3   X1 X2 X3   x1
     A           B       C

Answer 1

Using base graphics you can do this simply:

mydf <- data.frame( X1=c(A=2, B=4, C=1), X2=c(3,2,NA), X3=c(4,1,NA) )
barplot(t(as.matrix(mydf)), beside=TRUE)

Using additional calls to axis can give the labeling more like in the question.