search for: coherc

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2003 Aug 14
2
vectorization question
...Andy > -----Original Message----- > From: Alberto Murta [mailto:amurta at ipimar.pt] > Sent: Thursday, August 14, 2003 12:50 PM > To: r-help at stat.math.ethz.ch > Subject: [R] vectorization question > > > Dear all > > I recently noticed the following error when cohercing a > data.frame into a > matrix: > > > example <- matrix(1:12,4,3) > > example <- as.data.frame(example) > > example$V4 <- 0 > > example > V1 V2 V3 V4 > 1 1 5 9 0 > 2 2 6 10 0 > 3 3 7 11 0 > 4 4 8 12 0 > > example &...
2007 Jan 26
2
%*% in Matrix objects
Dear R users, I need to normalize a bunch of row vectors. At a certain point I need to divide a matrix by a vector of norms. I find that the behavior of Matrix objects differs from normal matrix objects. Example the following code examples differ only in xnormed changing from normal to Matrix object: x = matrix(1:12,3,4) x = as(x, "CsparseMatrix") xnorms = sqrt(colSums(x^2))