Hi all,
I want to extract every 20th row of a big matrix, say 10000 by 1000.
What is the simper way to do this?
Thank you very much!
Hannah
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Hannah, a <- matrix(rnorm(10000),nrow=500) new.matrix <- a[seq(0,dim(a)[1],by=20),] Jonathan On Tue, Oct 12, 2010 at 1:59 PM, li li <hannah.hlx at gmail.com> wrote:> Hi all, > ?I want to extract every 20th row of a big matrix, say 10000 by 1000. > What is the simper way to do this? > ? Thank you very much! > ? ? ? ? ? ?Hannah > > ? ? ? ?[[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >
> newmat <- oldmat[ c(rep(FALSE,19),TRUE), ]Or> newmat <- oldmat[ seq(20, nrow(oldmat), 20), ]-- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.snow at imail.org 801.408.8111> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r- > project.org] On Behalf Of li li > Sent: Tuesday, October 12, 2010 2:00 PM > To: r-help > Subject: [R] extract rows of a matrix > > Hi all, > I want to extract every 20th row of a big matrix, say 10000 by 1000. > What is the simper way to do this? > Thank you very much! > Hannah > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.