On Fri, May 06, 2011 at 02:28:57PM +1000, andre bedon wrote: > > Hi, > I'm hoping someone can offer some advice:I have a matrix "x" of dimensions > 160 by 10000. I need to create a matrix "y", where the first 7 elements are > equal to x[1]^1/7, then the next 6 equal to x[2]^1/6, next seven x[3]^1/7 and > so on all the way to the 10400000th element. I have implemented this with a > for loop an hour ago and it is still loading, can anyone offer any > suggestions as to how I can create this matrix without using loops? I would > really appreciate any suggestions.
Hi. Thanks to a remark by David, i now see that x[1]^1/7 is meant as x[1]^(1/7). The following is a solution modified accordingly x <- matrix(100, nrow=2, ncol=2) x <- x^c(1/7, 1/6) rep(x, times=rep(c(7, 6), length=length(x))) [1] 1.930698 1.930698 1.930698 1.930698 1.930698 1.930698 1.930698 2.154435 [9] 2.154435 2.154435 2.154435 2.154435 2.154435 1.930698 1.930698 1.930698 [17] 1.930698 1.930698 1.930698 1.930698 2.154435 2.154435 2.154435 2.154435 [25] 2.154435 2.154435 The output is a vector. You require that the output has 6.5 times more elements than the input, since 10400000/160/10000 = 6.5. This corresponds to the understanding that odd elements should repeat 7 times and even elements 6 times. However, it is not clear, what the dimension of the output matrix should be. Hope this helps. Petr Savicky. ______________________________________________ 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.
