Hi Jim, What you are saying is correct. Although, my computer might not have same speed and I am getting the following for 10M entries:
user system elapsed 0.559 0.038 0.607 Moreover, in the case of character vectors, it gets more than double. In my modeling, which is already highly time consuming, I need to do check this for few thousand vectors and the entries can easily be 10M in each vector. So I am just looking for any possibilities of time saving. I am pretty sure that whenever elements are not all equal, it can be concluded from any few entries (most of the times). It will be worth if I can find a way which stops checking further the moment it find two distinct elements. Regards Utkarsh jim holtman wrote: > 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 > <mailto: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 > <http://gerifalte28_at_hotmail.com/> > <mailto: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 <mailto:hdo...@air.org>> / > />To: <vincent.gou...@act.ulaval.ca > <mailto:vincent.gou...@act.ulaval.ca>>, <r-h...@stat.math.ethz.ch > <mailto: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> / > />[mailto: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 <mailto: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 > > <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 <http://vgoulet.act.ulaval.ca/> / > /> / > />______________________________________________ / > />r-h...@stat.math.ethz.ch <mailto: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 <mailto: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 <mailto: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? 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______________________________________________ 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.
