search for: zsort

I have two dataframe columns of POXIXct data/times that include seconds. I got them into this format using for example zsort$ETA <- as.POSIXct(as.character(zsort$ETA), format="%m/%d/%Y %H:%M:%S") My problem is that when I subtract the two columns, sometimes the difference is given in seconds, and sometimes it is given in minutes. I don't care which it is, but I need to know which one I will get. DateTi...

Hello, has anybody written a function to plot density ellipses (95%, 99% or anything) in a scatterplot? I found nothing in any package, nor in the list archives. There does seem to be a contributed package "ellipse" for S-Plus (on S-Archive), but it does a lot more than what I would need. Still, if anybody ported it to R, I'd be grateful for a link. I'm a bit afraid to try the