Perhaps ignore the lower-triangularity for a moment and do something like this:
x <- matrix(NA, ncol = max(j), nrow = max(i)) x[i, j] <- k Your code will be clearer if you use with() rather than df$i constructs. Hope this helps, Michael On Wed, Feb 15, 2012 at 11:47 AM, nymphita <sandrablazquezcabr...@gmail.com> wrote: > Hi Tsjerk! > > Thanks for your quick reply! > It's a nice way to built a lower triangular matrix with zeros in the > diagonal, but what I can't work out is *how to include the values of the > third column of the dataframe inside the matrix*. > > I just realized that I forgot to explain something about the dataframe (the > meaning of i, j ,k) in my post: > The data frame has three columns, the first one (i) corresponds to the "row > subscript" of the matrix [i, ], the second one (j) corresponds to the > "column subscript" of the matrix [ ,j], and the third column in the > dataframe (k) is the value that has to be in the matrix (in position [i, > j]). > > http://r.789695.n4.nabble.com/file/n4391099/df.png > > The result is that the dataframe gives you a position and a value in a lower > triangular matrix: > > http://r.789695.n4.nabble.com/file/n4391099/matrix.png > > Still can't find a solution to built a lower triangular matrix with the > specific values of that dataframe... > Any more ideas, please? > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/built-a-lower-triangular-matrix-from-dataframe-tp4390813p4391099.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.
