It behaves as per documentation.
" Using diag(x) can have unexpected effects if x is a vector that could be of length one. Use diag(x, nrow = length(x)) for consistent behavior." Ravi ________________________________ From: R-devel <r-devel-boun...@r-project.org> on behalf of Gábor Csárdi <csardi.ga...@gmail.com> Sent: Monday, September 17, 2018 12:22:31 PM To: li...@revelle.net Cc: r-devel Subject: Re: [Rd] diag(-1) produces weird result I would say it is a mis-feature. If the 'x' argument of diag() is a vector of length 1, then it creates an identity matrix of that size, instead of creating a 1x1 matrix with the given value: ❯ diag(3) [,1] [,2] [,3] [1,] 1 0 0 [2,] 0 1 0 [3,] 0 0 1 Of course this makes it cumbersome to use diag() in a package, when you are not sure if the input vector is longer than 1. This seems to be a good workaround: ❯ diag(-1, nrow = 1) [,1] [1,] -1 Or, in general if you have vector v: ❯ v <- -1 ❯ diag(v, nrow = length(v)) [,1] [1,] -1 Gabor On Mon, Sep 17, 2018 at 5:14 PM William Revelle <li...@revelle.net> wrote: > > Dear list > > A strange bug in the psych package is due to the behavior of the diag > function: > > It gives the expected values for 1, a vector (-1,1), but not for -1 > > Is this a known feature? > > > > diag(1) > [,1] > [1,] 1 > > diag(c(-1,1)) > [,1] [,2] > [1,] -1 0 > [2,] 0 1 > > diag(-1) > Error in diag(-1) : invalid 'nrow' value (< 0) > > > Bill > > > William Revelle personality-project.org/revelle.html > Professor personality-project.org > Department of Psychology > www.wcas.northwestern.edu/psych/<http://www.wcas.northwestern.edu/psych/> > Northwestern University www.northwestern.edu/<http://www.northwestern.edu/> > Use R for psychology personality-project.org/r > It is 2 minutes to midnight > www.thebulletin.org<http://www.thebulletin.org> > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel