Sorry, I just realized that it's not a lower triangualr matrix, but an upper triangular matrix! But still the solution/s should be rather similar in both cases.
http://r.789695.n4.nabble.com/file/n4391127/matrix2.png I apologize for creating confusion... Nymphita -- View this message in context: http://r.789695.n4.nabble.com/built-a-lower-triangular-matrix-from-dataframe-tp4390813p4391127.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.