Okay thanks! No I have the following difficulty implementing a variogram in the nlme package:
> cd1 <- lme(count ~ time, data=cd4,random= ~ time | id) > plot(Variogram(cd1, form= ~ time | id, robust=TRUE)) Error in as.array(X) : attempt to set an attribute on NULL Im not sure how to fix this, and apply this function to a longitudinal data with unequal times? Any help would be appreciated Quoting Dan Bebber <[EMAIL PROTECTED]>: > Hi Matt, > > there are several R packages that will compute the sample variogram for > you. > Check out GeoR, sgeostat, nlme, spatial. There's no point in recoding the > whole lot yourself, unless as a learning excercise. > > D > > p.s. For time series autocorrelations, you could use acf in package stats. > > Message: 9 > Date: Mon, 25 Oct 2004 02:02:06 -0400 > From: [EMAIL PROTECTED] > Subject: [R] sample variogram construction > To: [EMAIL PROTECTED] > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=US-ASCII > > Hi > > Im attempting to build a sample variogram for 300 obersvations of > longitudinal data. So what I need to do is compute the half > squared differences between pairs of residuals (for instance if a subject > has 4 obersvations, this is 4 choose 2 paird differences) for each subject. > Also, then I need the corresponding time differences within each > individual. > So the end result will be a 300 by 2 matrix with columns corresponding to > paired difference residuals within subject and time differences within > subject. Basically im having trouble coding this kind of matrix in R, if > anyone can help me out or give me some tips id appreciate it. > > Thanks. > Stuck in the for loop > student > > ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
