Dear R-helpers , I have a simple loop as follows, however, to be more efficient, I would like to use any apply functions (tapply, I suppose) But how can I do this ? I am not very clear about this.
# Z is a P * Q matrix # so for each row of Z, I would like to pull out only some of the elements, and save as a separate matrix under a list # index is a vector with length smaller than Q, but the index could be different for each row of Z. for (i in 1:P) { tmp = matrix(Z[i, index], nrow=1) tmpr[[i]]=tmp } any help is highly appreciated!! Thank you all Carrie [[alternative HTML version deleted]] ______________________________________________ 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.