Or: which(apply(x == 0, 2, all))
On Wed, Sep 3, 2008 at 12:46 PM, Marc Schwartz <[EMAIL PROTECTED]>wrote: > on 09/03/2008 10:34 AM Chuck Cleland wrote: > > 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: > > > > 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 > > > > Another (column-wise) approach to this would be: > > x <- c(3,3,3,3,0,0,0,0,5,5,5,5,8,8,8,8) > x <- matrix(x, nrow=4) > > > which(apply(x, 2, function(i) all(i == 0))) > [1] 2 > > > x <- c(3,3,3,3,1,-1,1,-1,5,5,5,5,8,8,8,8) > x <- matrix(x, nrow=4) > > > which(apply(x, 2, function(i) all(i == 0))) > integer(0) > > > HTH, > > Marc Schwartz > > ______________________________________________ > 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.
