On Tue, 2005-09-27 at 19:12 +0200, Søren Højsgaard wrote: > In data OME in MASS I would like to extract the first 5 observations > per subject (=ID). So I do > > library(MASS) > OMEsub <- split(OME, OME$ID) > OMEsub <- lapply(OMEsub,function(x)x[1:5,]) > unsplit(OMEsub, OME$ID) > > - which results in > > [[1]] > [1] 1 1 1 1 1 > [[2]] > [1] 30 30 30 30 30 > [[3]] > [1] low low low low low > Levels: N/A high low > [[4]] > [1] 35 35 40 40 45 > [[5]] > [1] coherent incoherent coherent incoherent coherent > Levels: coherent incoherent > [[6]] > [1] 1 4 0 1 2 > > ............ > > [[1094]] > [1] 4 5 5 5 2 > [[1095]] > [1] 100 100 100 100 100 > [[1096]] > [1] 18 18 18 18 18 > [[1097]] > [1] N/A N/A N/A N/A N/A > Levels: N/A high low > There were 50 or more warnings (use warnings() to see the first 50) > > warnings() > Warning messages: > 1: number of items to replace is not a multiple of replacement length > 2: number of items to replace is not a multiple of replacement length > 3: number of items to replace is not a multiple of replacement length > .... > > According to documentation unsplit is the reverse of split, but I must > be missing a point somewhere... Can anyone help? Thanks in advance. > Søren
If you read the documentation for split/unsplit, you will also note that in the Details section it says: 'unsplit' works only with lists of vectors as opposed to lists of data frames, which is the result of your split() operation. Also note that in the Value section, it indicates: 'unsplit' returns a vector for which 'split(x, f)' equals 'value' as opposed to unsplit returning a data frame. Thus, use: OME1 <- do.call("rbind", OMEsub) where OME1 will be the result of rbind()'ing the data frames in the OMEsub list. See ?do.call for more information. HTH, Marc Schwartz ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html