On Fri, 2010-04-16 at 09:30 -0800, Kathie wrote: > Dear R users, > > I am looking for more efficient way to compute the followings > > -------------------------------------------------------------------------- > > a <- matrix(c(1,1,1,1,2,2,2,2),4,2) > b <- matrix(c(1,2,3,4),4,1)
Is there a reason why 'b' is a matrix? Anyway, if b is a matrix with more cols in your real world problem, sweep(a, 1, b[,1], "/") will get what you want. Otherwise sweep(a, 1, b, "/") will work whether b is a one col matrix or if you change it to a vector. HTH G > > Eventually, I want to get this matrix, `c`. > > c <- matrix(c(1/1,1/2,1/3,1/4,2/1,2/2,2/3,2/4),4,2) > > -------------------------------------------------------------------------- > > In fact, #column of `a` is so big.. > > Is there a more efficient way to compute this instead of using "apply" or > something? or "apply" is only way..? > > Any suggestion will be greatly appreciated. > > Regards, > > Kathryn Lord -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ 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.
