Thank- you all for you suggestions and help. I have now resolved my issue. This help forum is one of the things that makes R a great platform for statistics.
Stephen Cole Marine Ecology Lab Saint Francis Xavier University On Wed, Oct 8, 2008 at 8:07 AM, Erin Hodgess <[EMAIL PROTECTED]>wrote: > Actually, you will have duplicates with 400 pairs. > > Here you will have 13^2 pairs with replacement and 13*12 pairs without > replacement and with regard to order. > How about this: > > z <- unique(x) > > y <- expand.grid(z[1:13],z[1:13]) > > xx <- y[,1] != y[,2] > > y[xx,] > > Just another thought. > > Erin > > > On Wed, Oct 8, 2008 at 5:55 AM, Erin Hodgess <[EMAIL PROTECTED]> > wrote: > > For all possible pairs, you'll have 20^2 pairs. > > This is a way to do it: > > > > expand.grid(x[1:20],x[1:20]) > > > > HTH, > > Erin > > > > > > On Wed, Oct 8, 2008 at 4:43 AM, Jim Lemon <[EMAIL PROTECTED]> wrote: > >> Stephen Cole wrote: > >>> > >>> ... > >>> I have a vector of 20 values > >>> > >>> x <- c(20,18, 45, 16, 47, 47, 15, 26, > 14,14,12,16,35,27,18,94,16,26,26,30) > >>> > >>> 1. > >>> I want to select random pairs from this data set but do it without > >>> replacement exhaustively > >>> > >> > >> matrix(x[sample(1:20,20)],nrow=2) > >> > >> then step through the columns of the resulting matrix > >>> > >>> I know i can select random pairs without replacement using > >>> > >>> sample(N,n,replace=F) > >>> However i am wondering if there is any way to get 10 random pairs from > >>> this > >>> data set without repeating any of the data points > >>> that is to say if i got a (20, 94) for one pair, i would like to get 9 > >>> other > >>> pairs from the data without again getting 20 or 94? > >>> > >>> 2. > >>> The second thing i would like to do is be able to select all possible > >>> pairs > >>> of numbers and calculate each pairs variance. > >> > >> I think you want to use the combn function, but you are going to get a > lot > >> of pairs... > >> > >> Jim > >> > >> ______________________________________________ > >> 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. > >> > > > > > > > > -- > > Erin Hodgess > > Associate Professor > > Department of Computer and Mathematical Sciences > > University of Houston - Downtown > > mailto: [EMAIL PROTECTED] > > > > > > -- > Erin Hodgess > Associate Professor > Department of Computer and Mathematical Sciences > University of Houston - Downtown > mailto: [EMAIL PROTECTED] > [[alternative HTML version deleted]] ______________________________________________ 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.
