If you would post a subset of your data so that we can see what you are talking about, we could probably help you come up with a solution.
On Sat, Mar 3, 2012 at 7:50 PM, Mikhail Titov <m...@gmx.us> wrote: > Hello! > > I’m having stacked data in a data.frame with 2 factors, ordered POSIXct, and > actual value as numeric (as if for lattice::xyplot). > > I would like to calculate first difference using “diff” function within > corresponding subsets/partitions. Since data.frame is organized by factors > and has sorted dates, it seems like "by" is a good candidate for the job. > However it returns just a dumb list of vectors. > > It seems that I can use either expand.grid to remap results of "by" and hope > that I won't mess up order, or I can use "unique(subset(x,select=c(foo,bar)))" > > In overall it looks like quite many steps for such task not counting > assignment of those differences back to original data.frame starting from 2nd > position in each partition (as diff returns shorter vector). > > Am I on the right track or is there an easier way to do that? > > Mikhail > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? Tell me what you want to do, not how you want to do it. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
