built a lower triangular matrix from dataframe
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
<sandrablazquezcabrera at 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.
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