Yes, mean of a one element object is meanless, but I'm trying to avoid a ifelse in the sentence. The result of mean values of x and y is added at each loop to a data.frame (or any other object that could speed up the loop.
2009/8/3 ONKELINX, Thierry <thierry.onkel...@inbo.be> > Dear Paulo, > > Your object is a named vector. Apply() and colMeans() only work on > matrices and dataframes. So you need to convert the vector to a matrix > or data.frame. See the example below. Please not that calculating the > mean of one element is a waiste of time. > > # a named numerical vector > object <- c(x = 670, y = 314) > str(object) > class(object) > > #a data frame with two numerical vectors. > object2 <- data.frame(x = 670, y = 314) > str(object2) > class(object2) > colMeans(object2) > > HTH, > > Thierry > > > ------------------------------------------------------------------------ > ---- > ir. Thierry Onkelinx > Instituut voor natuur- en bosonderzoek / Research Institute for Nature > and Forest > Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, > methodology and quality assurance > Gaverstraat 4 > 9500 Geraardsbergen > Belgium > tel. + 32 54/436 185 > thierry.onkel...@inbo.be > www.inbo.be > > To call in the statistician after the experiment is done may be no more > than asking him to perform a post-mortem examination: he may be able to > say what the experiment died of. > ~ Sir Ronald Aylmer Fisher > > The plural of anecdote is not data. > ~ Roger Brinner > > The combination of some data and an aching desire for an answer does not > ensure that a reasonable answer can be extracted from a given body of > data. > ~ John Tukey > > -----Oorspronkelijk bericht----- > Van: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] > Namens Paulo Eduardo Cardoso > Verzonden: maandag 3 augustus 2009 16:19 > Aan: David Winsemius > CC: [R] > Onderwerp: Re: [R] apply function to named numeric object > > Both objects are numeric, but they differ in structure and I don't know > how to handle both with a single function to get means. > When I try to apply colMeans to a named numeric object like this: > > Named num [1:2] 670 314 > - attr(*, "names")= chr [1:2] "x" "y" > > I get the error messages: > > Error in colMeans(centroid) : > 'x' must be an array of at least two dimensions > > and apply(object,2,mean) > > Error in apply(object, 2, mean) : dim(X) must have a positive length > > There are something very basic that I'm missing. > > 2009/8/3 David Winsemius <dwinsem...@comcast.net> > > > > > On Aug 3, 2009, at 9:52 AM, Paulo Eduardo Cardoso wrote: > > > > Thanks. Works > > A doubt. > > > > I asked that because I have a loop that can generate objects like that > > > or this one > > > > > > str(object) > > Named num [1:2] 670 314 > > - attr(*, "names")= chr [1:2] "x" "y" > > > > To avoid using a ifelse() to calculate means of x and y, I'd like a > > function that handle with this named numeric object and that list. Any > > > chance of do it with a single function? > > > > > > I do not see any list object. Lists and arrays (of which the two > > dimensional ones are of type "matrix") are quite different basic data > > structures in R. If you interchange the use of those terms you will > > not get useful replies from R users. Those two object both appear to > > be matrices and both should be handled by those functions. > > > > > > 2009/8/3 David Winsemius <dwinsem...@comcast.net> > > > >> > >> On Aug 3, 2009, at 9:07 AM, Paulo Eduardo Cardoso wrote: > >> > >> Maybe a very basic question. > >>> How can I get mean of a object like this > >>> > >>> str(object) > >>>> > >>> num [1:53, 1:2] 734 734 736 734 736 ... > >>> - attr(*, "dimnames")=List of 2 > >>> ..$ : NULL > >>> ..$ : chr [1:2] "x" "y" > >>> > >>> I want the mean of both x and y > >>> > >> > >> apply(object, 2, mean) > >> > >> or... > >> > >> colMeans(object) # which will be faster > >> > >> > >> _______________ > >>> Paulo E. Cardoso > >>> > >>> [[alternative HTML version deleted]] > >>> > >>> __________________________________________ > >>> > >> > > > > David Winsemius, MD > > Heritage Laboratories > > West Hartford, CT > > > > > > > -- > _______________ > Paulo E. Cardoso > > [[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. > > Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver > weer > en binden het INBO onder geen enkel beding, zolang dit bericht niet > bevestigd is > door een geldig ondertekend document. The views expressed in this message > and any annex are purely those of the writer and may not be regarded as > stating > an official position of INBO, as long as the message is not confirmed by a > duly > signed document. > -- _______________ Paulo E. Cardoso [[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.
