Hey together, thanks a lot for the quick and helpful answers. I will not use median on a data.frame from now on and use sapply instead.
Thanks Christoph On Thu, May 26, 2011 at 11:37 PM, Marc Schwartz <marc_schwa...@me.com> wrote: > On May 26, 2011, at 4:22 PM, Christoph Jäckel wrote: > >> Hi together, >> >> below is a small example which produces outcome I do not understand, >> namely that the median function works fine on a data.frame without >> negative numbers, but doesn't work on a data.frame with one negative >> number. I'm sure there is a reasonable explanation for that or better, >> that I'm doing something wrong and someone could guide me how to solve >> it. I tried googling it, but couldn't find a solution: >> >>> #Set up data frame >>> df <- data.frame(V1=c(1,2,3,4),V2=c(2,3,4,5)) >>> #Both work fine >>> mean(df) >> V1 V2 >> 2.5 3.5 >>> median(df) >> [1] 2.5 3.5 >>> >>> #Now, I just make one number negative in the data.frame >>> df <- data.frame(V1=c(1,2,3,-4),V2=c(2,3,4,5)) >>> mean(df)#Works fine >> V1 V2 >> 0.5 3.5 >>> median(df)#Why do I get that error? >> [1] NA 0.5 >> Warnmeldung: >> In mean.default(X[[1L]], ...) : >> argument is not numeric or logical: returning NA >>> #It works fine on both columns seperately >>> median(df$V1) >> [1] 1.5 >>> median(df$V2) >> [1] 3.5 > > > This was actually just discussed late last month. See the thread here: > > https://stat.ethz.ch/pipermail/r-devel/2011-April/060731.html > > The bottom line is that median does not have a 'method' for data frames, > whereas mean does. > > HTH, > > Marc Schwartz > > -- -------------------------------------------------------------------------------------------------------------------------------------------------------------------- Christoph Jäckel (Dipl.-Kfm.) -------------------------------------------------------------------------------------------------------------------------------------------------------------------- Research Assistant Chair for Financial Management and Capital Markets | Lehrstuhl für Finanzmanagement und Kapitalmärkte TUM School of Management | Technische Universität München Arcisstr. 21 | D-80333 München | Germany Mailto: christoph.jaec...@wi.tum.de | Web: www.fm.wi.tum.de Phone: +49 89 289 25482 | Fax: +49 89 289 25488 Head of Chair: Univ.-Prof. Dr. Christoph Kaserer ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- E-Mail Disclaimer Der Inhalt dieser E-Mail ist vertraulich und ausschliesslich fuer den bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte, dass jede Form der Kenntnisnahme, Veroeffentlichung, Vervielfaeltigung oder Weitergabe des Inhalts dieser E-Mail unzulaessig ist. Wir bitten Sie, sich in diesem Fall mit dem Absender der E-Mail in Verbindung zu setzen. The information contained in this email is confidential....{{dropped:11}} ______________________________________________ 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.
