[EMAIL PROTECTED] napsal dne 03.09.2008 17:34:24: > On 9/3/2008 11:05 AM, Petr PIKAL wrote: > > [EMAIL PROTECTED] napsal dne 03.09.2008 15:54:08: > > > >> try this: > >> > >> x <- c(3,3,3,3,0,0,0,0,5,5,5,5,8,8,8,8) > >> x <- matrix(x, nrow=4) > >> > >> which(colSums(x == 0) == nrow(x)) > > > > Isn't this the same? > > > > which(colSums(x)==0) > > No, because the column sum can be zero without each element being zero: >
OK you got me. What about which(colSums(abs(x))==0) and yes, I am aware of floating point arithmetic, so better approach would be which(colSums(abs(x))<some.small.value) Regards Petr > x <- c(3,3,3,3,1,-1,1,-1,5,5,5,5,8,8,8,8) > x <- matrix(x, nrow=4) > > > which(colSums(x == 0) == nrow(x)) > integer(0) > > > which(colSums(x)==0) > [1] 2 > > > Regards > > Petr > > > >> I hope it helps. > >> > >> Best, > >> Dimitris > >> > >> > >> Muhammad Azam wrote: > >>> Dear R community > >>> I have a problem regarding which of the column in a matrix contains > > all of > >> zero elements. e.g. > >>> x=c(3,3,3,3,0,0,0,0,5,5,5,5,8,8,8,8); x=matrix(x, nrow=4) > >>> the output is > >>> > >>>> x > >>>> > >>> [,1] [,2] [,3] [,4] > >>> [1,] 3 0 5 8 > >>> [2,] 3 0 5 8 > >>> [3,] 3 0 5 8 > >>> [4,] 3 0 5 8 > >>> In this case the required column is second so the result should be > > "2". How > >> can i get it? > >>> > >>> best regards > >>> > >>> Muhammad Azam > >>> > >>> > >>> > >>> > >>> [[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. > >>> > >>> > >> > >> -- > >> Dimitris Rizopoulos > >> Assistant Professor > >> Department of Biostatistics > >> Erasmus University Medical Center > >> > >> Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands > >> Tel: +31/(0)10/7043399 > >> Fax: +31/(0)10/7044657 > >> > >> ______________________________________________ > >> 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. > > > > ______________________________________________ > > 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. > > > > > -- > Chuck Cleland, Ph.D. > NDRI, Inc. (www.ndri.org) > 71 West 23rd Street, 8th floor > New York, NY 10010 > tel: (212) 845-4495 (Tu, Th) > tel: (732) 512-0171 (M, W, F) > fax: (917) 438-0894 > > ______________________________________________ > 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. ______________________________________________ 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.
