If DF is your data frame then create a time column like this: DF$time <- ave(DF$DaysAgo, DF$PID, FUN = seq_along)
and now use the reshape command on DF (or melt/cast from the reshape package). On Thu, Apr 24, 2008 at 2:13 PM, Tubin <[EMAIL PROTECTED]> wrote: > > hi, I'm a total noob who is having to ramp up to full speed very quickly due > to an unfortunate abrupt staffing change at my job :) > > I have longitudinal data that looks like this: > PID OBSDATE DaysAgo CleanValue > NAME > 1 1410164934000610 8/17/2004 13:03:38 1345 6.2 HGBA1C > 2 1410164934000610 11/16/2004 10:39:51 1254 7.1 HGBA1C > ...etc > > I'd like to end up with a wide-format table like: > PID OBSDATE.1 DaysAgo.1 CleanValue.1 [...] OBSDATE.n DaysAgo.n > CleanValue.n > > The problem: Every patient's on a different schedule, so there's no natural > timevar value to reshape with. > > My solution involved creating another column for the timevar and looping > through the dataframe to populate that column with correct values; however, > it's a pretty big table and so the loop runs really slowly. I need to do > this particular operation on quite a few datafiles on a regular basis, and > my database keeps getting bigger - so I anticipate this solution won't be > ideal in the future. > > Can anyone recommend a more efficient solution? > > -- > View this message in context: > http://www.nabble.com/reshaping-%22long-form%22-longitudinal-data-from-sql-query-tp16851308p16851308.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > ______________________________________________ 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.
