Inline Below. -- Bert
Bert Gunter Genentech Nonclinical Biostatistics 650-467-7374 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Wacek Kusnierczyk Sent: Sunday, March 22, 2009 2:16 AM To: rkevinbur...@charter.net Cc: r-help@r-project.org Subject: Re: [R] variance/mean rkevinbur...@charter.net wrote: > At the risk of appearing ignorant why is the folowing true? > > o <- cbind(rep(1,3),rep(2,3),rep(3,3)) > var(o) > [,1] [,2] [,3] > [1,] 0 0 0 > [2,] 0 0 0 > [3,] 0 0 0 > > and > > mean(o) > [1] 2 > > How do I get mean to return an array similar to var? I would expect in the above example a vector of length 3 {1,2,3}. > You said: "you may well be ignorant about how var works with matrices, but this does not mean it's your fault. the documentation is typically cryptical." -- How so? ?var clearly states: " ... If x and y are matrices then the covariances (or correlations) between the columns of x and the columns of y are computed. " and the Arguments section says: x a numeric vector, matrix or data frame. y NULL (default) or a vector, matrix or data frame with compatible dimensions to x. The default is equivalent to y = x (but more efficient). This is as clear as I would know how to state. I think "...typically cryptical" is a canard and most unfair. -- Bert ______________________________________________ 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.
