R help - Feb 2005 - Trying to get a side-by-side barplot of data with levels (Modified by List account)

Greetings!

This is probably a simple problem, but it's really got me flummoxed.  I 
have some data, basically a vector with a factor, in the following 
format, which I read in via 'auth <-
read.table("authorship.csv",
header=TRUE, sep=",")':

normalized.thomistic,category
1,116.0381739855475264,1
2,131.2574467426990769,1
3,136.4285134675765673,1
...
169,62.3858353841946951,3
170,9.7790398628375482,3
171,46.6410161421995376,3
172,103.7494315597999090,3
174,28.8608475648323846,3

What I'm tying to get is a barplot which will plot the number of data 
points in each category in a quartile format, with the categories side 
by side.  For instance, there should be four groups of bars, the first 
being the number of data points in the bottom quartile, for categories 
1, 2, and 3 side by side... next the number of data points in second 
quartile in the same format, etc.

Thanks for any help you can offer!
-Erik Norvelle

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