[R] Help: Side-by-side named barplot bars

[Sergey Goriatchev]

Hello,

Let me describe what I have and what I want to do:

I have two (7x6) matrices (call them A and B) that have same row and
column names (rows=species, columns=variables) but contain numerical
values that differ (same experiment done twice and values calculated
and put in different matrices).

Up to now I was producing two set of barplots, each set for each
matrix of values.
On each page I presented two barplots:
For each row of matrix A I plotted the values ofvariables as vertical
bars (6 bars), the names under the bars were column names from the
matrix, and I also put the value as text at the top of the bar (with
text() function). The second barplot was for the same row in B matrix.
By putting them on the same page in a pdf document I can look at the
bars for each variable and the values texted on the bars and compare
the differences between two experiments.

But this is not very effective. What I want to do is to combine the
two similar barplots for each experiment into one. So, for each
species I create just one barplot where I plot 6 clusters each
consisting of 2 bars, one bar for same varibale but different
experiment. I want to put the values as text at the top of each bar
and below each cluster I want to put the name of the variable (they
are the same for each experiment, remember).

I remembered that Michael Crawley did a side-by-side barplot in his
Introduction to R book, I used his idea before but now I have two
matrices and his method is not applicable.

Could someone please advise me how to do these side-by-side barplots?
A little bit of code showing the procedure would be appreciated.

Thank you in advance!

Best,
Sergey G
University of Zurich

P.S. I do not grasp how to post replies to my own posts (want to thank
the people that take their time to help out. Want to thank Gregory
Warnes for letting me know of gplots package, now my plots are very
informative!). Do I just put in the subject of email the name of my
previous post?