François Pinard wrote: > [Berton Gunter] > >>[Sam Steingold] > > >>>PPS. how do I figure out the number of rows in a data.frame? >>> is length(attr(X,"row.names")) the right way? > > >>help.search("number of rows") immediately gets you your answer! > > > Hi, people. Here, I get: > > Help files with alias or concept or title matching ‘number of rows’ > using fuzzy matching: > > nrow(base) The Number of Rows/Columns of an Array > > and '?nrow' says that it meant for arrays: nothing about data.frame, and
Very well about data.frames! ?nrow says in its argument description: "x a vector, array or data frame " Uwe Ligges > not a generic method either. Even if it was a class method, we should > not expect a new user to be very familiar with R (both!) class systems > from the start. > > What a new user might think, reading the documentation? Sam Steingold > is surely an experimented and competent computer guy. He might guess, > who knows, that some automatic array to data.frame conversion occurs > (all inefficient that it could be). Yet this would not match other > knowledge nor experimentation, as a data.frame is hardly an array: > > > x = data.frame(a=1:3, b=c(TRUE, TRUE, FALSE), c=letters[1:3]) > > as.array(x) > Erreur dans "dimnames<-.data.frame"(`*tmp*`, value = list(c("a", "b", "c" : > 'dimnames' incorrect pour ce tableau de données > > Despite help.search("number of rows") provides an answer that happens to > be right, it might not be recognised as such by an intelligent reader, > and so, it is not really satisfactory. The documentation for "nrow" > could be improved by saying that it applies to any kind of structure for > which dim() is meaningful. And even then, ?dim is silent about data > frames. One clue (yet a pretty weak one) that nrow may be applied to > a data.frame comes from the fact that ?dim.data.frame lists the same > documentation as ?dim. > > > Why do I say all this? Because it happens, not necessarily in this > case, a bit too often nevertheless, that answers given to users are > uselessly harsh or haughty. Especially when they imply that the > documentation is perfect. One problem is that some people enjoy reading > such replies. As example of this strange kind of pleasure, here is > a excerpt from R Archives, which I find especially enlightening on the > mentality of few members: > > From: [EMAIL PROTECTED] (Steve Wisdom) > Date: 2003-12-26 17:04 > Subject: [R] re| Dr Ward on List protocol > > "Andrew C. Ward" <[EMAIL PROTECTED]> : > > >With respect to 'tone' and 'friendliness', perhaps all that is meant or > >needed is that people be polite and respectful. > > >I shake my head as often at rude answers > > Oh, by gosh, by golly. > > I don't think an occasional dose of 'real life', via a jab from the > Professor, will cause any lasting harm to the cosseted & emolumated students > and academics on the List. > > On a Wall St trading desk, for example, every day one is kicked in the head > more brutally by clients, superiors, counterparts, the markets & etc, than > ever one would be by the Professor. > > Plus, the Professor's jabs are good Schadenfreudic fun for the rest of us. > > Regards, > > Steve Wisdom > Westport CT US > > The truth is that not everybody around here is "cosseted & emolumated > students and academics". Moreover, behaviour at trading desks is fully > irrelevant, and for most of us, this is not the kind of life we chose to > live. Wrong behaviour elsewhere is hardly an excuse for not behaving > properly, here. > > Moreover, what is mere "good fun" for some may be perceived as highly > inelegant by others. While some competent members may inspire > admiration and charism by their knowledge and dedication, they sometimes > damage beyond repair what they inspire, when showing poor humanity. > > I'm aware of the constant fear some have of seeing this list abused. > There are ways for not being abused, which do not require becoming > abusive ourselves. We should deepen such ways in our own habits. > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html