Re: [R] unique, but keep LAST occurence

From: <davidr_at_rhotrading.com>
Date: Tue 25 Jul 2006 - 04:03:43 EST


Thank you, Bert and Mark.
I believe Mark's solution works, but it was taking a very long time. Bert's is very fast.

My day is saved!

David L. Reiner
Rho Trading Securities, LLC
Chicago IL 60605
312-362-4963

-----Original Message-----
From: Berton Gunter [mailto:gunter.berton@gene.com] Sent: Monday, July 24, 2006 12:51 PM
To: David Reiner <davidr@rhotrading.com>; r-help@stat.math.ethz.ch Subject: RE: [R] unique, but keep LAST occurence

Try:

 largestDF <- DF[nrow(DF)- which(!duplicated(rev(DF$t)))+1,]

You can then sort this however you like in the usual way. Row names will be preserved.

"The business of the statistician is to catalyze the scientific learning process." - George E. P. Box    

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of
> davidr@rhotrading.com
> Sent: Monday, July 24, 2006 10:00 AM
> To: r-help@stat.math.ethz.ch
> Subject: [R] unique, but keep LAST occurence
>
> ?unique says
>
> Value:
>
> An object of the same type of 'x'. but if an element is equal to
> one with a smaller index, it is removed.
>
> However, I need to keep the one with the LARGEST index.
> Can someone please show me the light?
> I thought about reversing the row order twice, but I couldn't
> get it to work right
>
> (My data frame has 125000 rows and 7 columns,
> and I'm 'uniqueing' on column #1 (chron) only, although the
> class of the column may not matter.)
>
> Say, e.g.,
> > DF <- data.frame(t = c(1,2,3,1,4,5,1,2,3), x = c(0,1,2,3,4,5,6,7,8))
>
> I would like the result to be (sorted as well)
> t x
> 1 6
> 2 7
> 3 8
> 4 4
> 5 5
>
> If I got the original rownames, that would be a bonus (for debugging.)
>
> > R.version
> _
> platform i386-pc-mingw32
> arch i386
> os mingw32
> system i386, mingw32
> status
> major 2
> minor 3.1
> year 2006
> month 06
> day 01
> svn rev 38247
> language R
> version.string Version 2.3.1 (2006-06-01)
>
> Thanks for any hints!
> David
>
> David L. Reiner
> Rho Trading Securities, LLC
> Chicago  IL  60605
> 312-362-4963
>
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
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>



R-help@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 and provide commented, minimal, self-contained, reproducible code. Received on Tue Jul 25 05:31:56 2006

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