[R] barplot groups of different size i.e. height is NOT a matrix

[Victor Gabillon]

Hello,

I want to use the function barplot do display several group of bars.
A standard example is given at this link
http://onertipaday.blogspot.com/2007/05/make-many-barplot-into-one-plot.html

But in their example the 4 groups of bars are all composed of 8 bars.
I want to be able do display the same kind of graph but where the number 
of bars in each group are not the same. For example the first group of 
bars would have 2 bars and the second group of bars would have 10 bars.

barplot function has a first parameter named height which is a matrix 
where each line  are the values  for the bars of one particular group.
One solution could be to have a height matrix with NA values but then 
the space occupied by each group is equal to the size of the largest 
group!! So you end up with gaps (empty) where there are NAs.

Do you know how to solve this problem?
Do i have to consider multiple barplots in the same plot with the same 
axis? (btw, i don't know how to do that)

In fact the bar would represent the performance of an algorithm.
A group of bars would be the performance of an algorithms with different 
parameters.
But when comparing different algorithms it is possible that we don't 
want to display the same number of parameters for each algorithm.

Thanks for your help.
Victor