If I understand your question: x$IAC0 <- with(x, ave(IAC, list(ProfA, Key), FUN = mean))
On Wed, Apr 30, 2008 at 3:52 PM, Chip Barnaby <[EMAIL PROTECTED]> wrote: > Dear all -- > > I have a data frame containing data related to heat gain through windows. > The general form is ... > > Key ProfA IAC <many other numeric columns> > AAA 0 .7 > AAA 10 .6 > AAA 0 .66 > AAA 20 .45 > (more AAA rows) > (then AAB rows) > > 'Key' identifies the physical configuration ... rows with a given Key > contain data for same window under various conditions. > > I want to add a column IAC0 containing, for each Key, the mean IAC of all > rows with ProfA == 0. > > The general approach I think I need is approximately (the following is not > known to run) -- > > 1) XS<-subset( X, ProfA < .01) to get the ProfA == 0 rows. This could be > done implicitly as part of step 2, I suppose. > > 2) X0<-aggregate( XS[,"IAC"], by=list( Key=XS$Key), mean) > > 3) XF<-merge( X, X0, by="Key") > > 4) Change new col name to "IAC0" (see Question 2). > > Question 1: Is this a reasonable way to solve my problem? > > Question 2: The aggregate() result has 2 columns: "Key" and "x". Can the > name of the mean column be specified (short of renaming after the fact)? > All the aggregate() examples (e.g. in help()) elegantly produce the "right > result" with nicely named columns etc. I can't seem to make things work so > smoothly. > > Thanks! > > Chip Barnaby > > > > > > > > > > --------------------------------------------------------- > Chip Barnaby [EMAIL PROTECTED] > Vice President of Research > Wrightsoft Corp. 781-862-8719 x118 voice > 131 Hartwell Ave 781-861-2058 fax > Lexington, MA 02421 www.wrightsoft.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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O [[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.
