[R] Titles in plots generated within tapply

[Christos Hatzis]

You were close with mapply.  You can pass the labels as a second argument to
your function
To take advantage of the vectorized nature of mapply:

mapply(function(x,y) barplot(table(x), xlab = 'Result',
main=paste("Group",y,sep="-")),
 split(result, group), levels(group)) 

-Christos

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Dennis Malandro
Sent: Thursday, February 02, 2006 1:35 AM
To: R-help at stat.math.ethz.ch
Subject: [R] Titles in plots generated within tapply

How would one go about putting titles in each of several plots that are
generated from within a call to tapply?  For example I'd like the following
two barplots to have titles 'Group 1' and 'Group 2', where '1' and '2' come
from the levels of 'group'.

group <- gl(2, 10)
result <- sample(c('A', 'B'), size=length(group), replace=TRUE) windows(7,
4) par(mfrow = c(1, 2)) tapply(result, group,
       function(x) barplot(table(x), xlab = 'Result'))


I found something close to what I'm looking for here
http://tolstoy.newcastle.edu.au/R/help/04/09/3219.html.  So I tried

mapply(function(x) barplot(table(x), xlab = 'Result'),
  split(result, group), main = levels(group))

Error in function (x)  : unused argument(s) (main ...)

(I expected to get titles of '1' and '2'.  Not exactly what I asked for in
the question, but it would have been progress.)

Much obliged,
Dennis

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