It probably does... I did not look at his until just now, my guess is they are equivalent. There are usually at least a couple ways to do things in R, no problem :). With massive datasets, it might make sense to try a couple different ways to see if one or the other is faster though.
You could also replace "!duplicated" in my function with "unique" ... Erik > -----Original Message----- > From: Dimitri Liakhovitski [mailto:[email protected]] > Sent: Monday, September 21, 2009 2:02 PM > To: Erik Iverson > Cc: R-Help List > Subject: Re: [R] More elegant way of excluding rows with equal values in > any 2 columns? > > Thank you very much, both Dimitris and Erik. > Erik - you are right, I was trying to remove any duplication (i.e., if > there are the same values in 2 or 3 or 4 columns). > And it looks like that's what your solution does. > But doesn't it do the same thing as Dimitris' solution? > > Dimitri > > On Mon, Sep 21, 2009 at 2:55 PM, Erik Iverson <[email protected]> wrote: > > Hello, > > > > Do you mean exactly any 2 columns. What if the value is equal in more > than 2 columns? > > > >> > >> I built a data frame "grid" (below) with 4 columns. I want to exclude > >> all rows that have equal values in ANY 2 columns. Here is how I am > >> doing it: > >> > >> index<-expand.grid(1:4,1:4,1:4,1:4) > > > > If a value is equal in 2 or more rows, i.e., duplicated, then the > following should work, assuming index can be changed to a matrix for apply > ... > > > > t3 <- index[apply(index, 1, function(x) all(!duplicated(x))),] > > > > > > -- > Dimitri Liakhovitski > Ninah.com > [email protected] ______________________________________________ [email protected] 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.
