[R] plot() help

[Andrew Perrin]

Please forgive my ignorance on grapics. I'm trying to make a relatively
simple plot with two line plots, same axes, by mean over a series of
dates. I can make the plot well like this:

plot(sort(tapply(first.anti.auth.sum,date,mean), partial=1), type="l",
col="yellow",ylim=c(0,2.0))
par(new=TRUE)
plot(sort(tapply(first.pro.auth.sum,date,mean), partial=1), type="l",
col="red",ylim=c(0,2.0))

but I would like the X axis to be dates, not index numbers. The trick is
that the "date" column across which the means are calculated returns
integers; I'd like to use, effectively:

format.POSIXct(as.POSIXct(date), '%b %d')

...but don't know how to make that happen.

Thanks for any advice.

----------------------------------------------------------------------
Andrew J Perrin - http://www.unc.edu/~aperrin
Assistant Professor of Sociology, U of North Carolina, Chapel Hill
clists at perrin.socsci.unc.edu * andrew_perrin (at) unc.edu