new.mat <- mat[ , colSums( mat==0 ) == 0, drop=FALSE ] This works great. I'm learning this R slowly... It is quite powerful.
Thanks -----Original Message----- From: Charles C. Berry [mailto:[EMAIL PROTECTED] Sent: Tuesday, January 15, 2008 3:47 PM To: My Coyne Cc: [EMAIL PROTECTED] Subject: RE: [R] Newbie Question -- Remove entire column in a matrix On Tue, 15 Jan 2008, My Coyne wrote: > Really Cool. THANK YOU > > Both works, only that New.mat is t is being transposed. So, I added a > minor change: > > New.mat <- matrix (mat [,colSums(mat==0) == 0], byrow = TRUE) I do not think that is what you want. If there are k columns after subscripting mat, the result will be a k*nrow(mat) by 1 matrix. The code below does not transpose the result. It will return a vector if only one column has colSums( mat==0 ) == 0. If a vector is not what you want, use the drop=FALSE argument new.mat <- mat[ , colSums( mat==0 ) == 0, drop=FALSE ] Chuck > > > > > > > -----Original Message----- > From: Charles C. Berry [mailto:[EMAIL PROTECTED] > Sent: Tuesday, January 15, 2008 12:34 PM > To: My Coyne > Cc: [EMAIL PROTECTED] > Subject: Re: [R] Newbie Question -- Remove entire column in a matrix > > On Tue, 15 Jan 2008, My Coyne wrote: > >> >> >> I'm ordering "The R Book" and hope to learn a lot more about R. In a >> meantime, I have a matrix of digits and I would like to look for a column >> that contains zeroes and remove the entire column from the matrix. I can >> write a piece of R code to do that (and it works); however, I think the >> R-experts have more tricks to do such a 'simple' thing. > > Is one of these what you want? > > new.mat <- mat[ , colSums( mat==0 ) == 0 ] > > new.mat <- mat[ , colSums( mat==0 ) < nrow(mat) ] > > > HTH, > > Chuck > >> >> >> >> Many thanks in advance. >> >> >> >> --My Coyne >> >> >> >> >> >> >> [[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. >> > > Charles C. Berry (858) 534-2098 > Dept of Family/Preventive > Medicine > E mailto:[EMAIL PROTECTED] UC San Diego > http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 > > > > Charles C. Berry (858) 534-2098 Dept of Family/Preventive Medicine E mailto:[EMAIL PROTECTED] UC San Diego http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 ______________________________________________ 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.
