On Jan 30, 2015, at 3:03 PM, Steven Yen wrote: > Dear > I use sm2vec from package corpcor to puts the lower triagonal entries of a > symmetric matrix (matrix A) into a vector. However, sm2vec goes downward > (columnwise, vector B), but I would like it to go across (rowwise). So I > define a vector to re-map the vector (vector C). This works. But is there a > short-cut (simpler way)? Thank you.
What about using this sequence to instead extract from the original A-Matrix: c(2, unlist( sapply( 3:6, function(n) c( n, n+6*seq(n-2) ) )) ) [1] 2 3 9 4 10 16 5 11 17 23 6 12 18 24 30 > idx <- c(2, unlist( sapply( 3:6, function(n) c( n, n+6*seq(n-2) ) )) ) > A[idx] [1] 0.52408090 0.47996616 0.54135982 0.11200672 -0.15985028 -0.06823105 [7] -0.17511030 -0.26277380 -0.20468970 0.22113110 -0.09276455 -0.14184545 [13] -0.23815967 0.08977677 0.23567235 > > > A<-cor(e); A > [,1] [,2] [,3] [,4] [,5] [,6] > [1,] 1.00000000 0.5240809 0.47996616 0.11200672 -0.1751103 -0.09276455 > [2,] 0.52408090 1.0000000 0.54135982 -0.15985028 -0.2627738 -0.14184545 > [3,] 0.47996616 0.5413598 1.00000000 -0.06823105 -0.2046897 -0.23815967 > [4,] 0.11200672 -0.1598503 -0.06823105 1.00000000 0.2211311 0.08977677 > [5,] -0.17511026 -0.2627738 -0.20468966 0.22113112 1.0000000 0.23567235 > [6,] -0.09276455 -0.1418455 -0.23815967 0.08977677 0.2356724 1.00000000 > > B<-sm2vec(A); B > [1] 0.52408090 0.47996616 0.11200672 -0.17511026 -0.09276455 > [6] 0.54135982 -0.15985028 -0.26277383 -0.14184545 -0.06823105 > [11] -0.20468966 -0.23815967 0.22113112 0.08977677 0.23567235 > > jj<-c(1,2,6,3,7,10,4,8,11,13,5,9,12,14,15) > > C<-B[jj]; C > [1] 0.52408090 0.47996616 0.54135982 0.11200672 -0.15985028 > [6] -0.06823105 -0.17511026 -0.26277383 -0.20468966 0.22113112 > [11] -0.09276455 -0.14184545 -0.23815967 0.08977677 0.23567235 > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
