Hi [EMAIL PROTECTED] napsal dne 21.04.2008 09:03:30:
> > Dear R users, > > I have 32 observations in data x. After sorting this, I want to compute > means and variances of 3 groups divided by "nr". > > Actually, the number of groups is flexible. Any suggestion will be greatly > appreciated. > > Kathryn Lord > > --------------------------------------------------------------------------- > x=rnorm(32) > y=sort(x) > > nr=matrix(c(12,11,10,10,10,11),2,3) > > nr > [,1] [,2] [,3] > [1,] 12 10 10 -> sum=32 > [2,] 11 10 11 -> sum=32 > > For the 1st row in "nr", index of y = (1,..,12, 13,...,23, 24,...32) > > I want to compute means and variances for 3 groups > > (1st group is 1 through 12; 2nd group is 13-23; 3rd group is 24-32) > > > For the 2nd row in "nr", index of y = (1,..,11, 12,...,22, 23,...32) > > also, I want to compute means and variances for 3 groups > > (1st group is 1 through 11; 2nd group is 12-22; 3rd group is 23-32) > If you know that your vector is sorted you can do sapply(split(y,rep(1:3, times=nr[1,])), mean) Regards Petr > > > -- > View this message in context: http://www.nabble.com/means-and-variances-of- > several-groups-in-the-matrix-tp16803939p16803939.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. ______________________________________________ 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.
