[R] Adding time series to time graphs

[Simon Kiss]

Hello: I have done this before but cannot figure out how to do it again.

I would like to graph campaign evolution of news stories on certain topics. The campaign time period is as follows:

campaign<-seq.Date(from=as.Date('2011-09-06'), to=as.Date('2011-10-5'), by=1)

I have a table of newspaper story frequencies containing a certain word that can be turned into a data.frame (or not). I'll reproduce it as a data.frame

plotdf<-data.frame(story.dates=seq.Date(as.Date('2011-09-17'),as.Date('2011-09-30'), by=1), Freq=seq(1,14, by=1))

How do I overlay the frequency of newspaper stories in a line plot on a graph where the x-axis is a series of dates twice as long as the time series itself? The reason I'd like this is because I'd like to add a couple of other story time series as well. They may appear at other points in time in the campaign as well.

Thanks.
Simon Kiss