Just check that the first (or any other element) is equal to all the rest: > x = c(1,2,rep(1,10000000)) # 10,000,000 > system.time(print(all(x[1] == x))) [1] FALSE user system elapsed 0.18 0.00 0.19
> This was for 10M entries. On Tue, Jun 16, 2009 at 7:42 AM, utkarshsinghal < utkarsh.sing...@global-analytics.com> wrote: > > Hi All, > > There are several replies to the question below, but I think there must > exist a better way of doing so. > I just want to check whether all the elements of a vector are same. My > vector has one million elements and it is highly likely that there are > distinct elements in the first few itself. For example: > > > x = c(1,2,rep(1,100000)) > > I want the answer as FALSE, which is clear from the first two > observations itself and we don't need to check for the rest. > > Does anybody know the most efficient way of doing this? > > Regards > Utkarsh > > > > From: Francisco J. Zagmutt <gerifalte28_at_hotmail.com > <mailto:gerifalte28_at_hotmail.com > ?Subject=Re:%20%5BR%5D%20Testing%20if%20all%20elements%20are%20equal%20in%20a%20vector/matrix>> > > Date: Tue 30 Aug 2005 - 06:05:20 EST > > > Hi Doran > > The documentation for isTRUE reads 'isTRUE(x)' is an abbreviation of > 'identical(TRUE,x)' so actually Vincent's solutions is "cleaner" than > using identical :) > > Cheers > > Francisco > > />From: "Doran, Harold" <hdo...@air.org> / > />To: <vincent.gou...@act.ulaval.ca>, <r-h...@stat.math.ethz.ch> / > />Subject: Re: [R] Testing if all elements are equal in a vector/matrix / > />Date: Mon, 29 Aug 2005 15:49:20 -0400 / > /> / > >See ?identical > <http://tolstoy.newcastle.edu.au/R/help/05/08/11201.html#11202qlink1> > /> / > />-----Original Message----- / > />From: r-help-boun...@stat.math.ethz.ch / > />[mailto:r-help-boun...@stat.math.ethz.ch] On Behalf Of Vincent Goulet / > />Sent: Monday, August 29, 2005 3:35 PM / > />To: r-h...@stat.math.ethz.ch / > />Subject: [R] Testing if all elements are equal in a vector/matrix / > /> / > /> / > />Is there a canonical way to check if all elements of a vector or > matrix are / > />the same? Solutions below work, but look hackish to me. / > /> / > /> > x <- rep(1, 10) / > /> > all(x == x[1]) # == operator does not provide for small differences / > */>[1] TRUE / > */> > isTRUE(all.equal(x, rep(x[1], length(x)))) # ugly / > */>[1] TRUE / > */> / > />Best, / > /> / > />Vincent / > />-- / > /> Vincent Goulet, Associate Professor / > /> École d'actuariat / > /> Université Laval, Québec / > /> Vincent.Goulet_at_act.ulaval.ca<http://vincent.goulet_at_act.ulaval.ca/> > <mailto:Vincent.Goulet_at_act.ulaval.ca > ?Subject=Re:%20%5BR%5D%20Testing%20if%20all%20elements%20are%20equal%20in%20a%20vector/matrix> > http://vgoulet.act.ulaval.ca / > /> / > />______________________________________________ / > />r-h...@stat.math.ethz.ch mailing list / > />https://stat.ethz.ch/mailman/listinfo/r-help / > />PLEASE do read the posting guide! / > />http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>/ > /> / > />______________________________________________ / > />r-h...@stat.math.ethz.ch mailing list / > />https://stat.ethz.ch/mailman/listinfo/r-help / > />PLEASE do read the posting guide! / > />http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>/ > > [[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<http://www.r-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. > > -- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve? [[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.
