[R] pair matching query corrected
I posed this question imprecisely earlier and did not specify that the pairing needs to be one-to-one. A precise version of the question follows: Given two numeric vectors of possibly unequal length, I'd like to pair each element of the shorter vector with an element of the longer vector in a one-to-one relationship such that the sum of squared differences between the pairs is minimized. Can someone point me to an R function or an algorithm for accomplishing this? Many thanks to David Winsemius and Andy Liaw who replied with solutions to the problem where the pairing does not have to be one-to- one. Tom Thomas S. Dye, Ph.D. T. S. Dye & Colleagues, Archaeologists, Inc. Phone: (808) 529-0866 Fax: (808) 529-0884 http://www.tsdye.com [[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.
Re: [R] pair matching
So, given these vectors, what's the right answer? a <-c(1,2,3) b<-c(2, 3, 4 ,5, 6) 2,2,3 (distance =1) or 2,3,4 (distance=3)? I.e., is recycling of elements allowed or must the pairing be one-one? if the first, then: df <- expand.grid(a,b) df$dist <- with(df, (Var1-Var2)^2 ) head(df[order(df$dist),], min(length(a),length(b)) ) Var1 Var2 dist 2 2 2 0 6 3 3 0 1 1 2 1 -- David Winsemius - Original Message - From: "Thomas S. Dye" To: r-help@r-project.org Sent: Tuesday, May 12, 2009 10:02:29 AM GMT -08:00 US/Canada Pacific Subject: [R] pair matching Given two numeric vectors of possibly unequal length, I'd like to pair each element of the shorter vector with an element of the longer vector such that the sum of squared differences between the pairs is minimized. Can someone point me to an R function or an algorithm for accomplishing this? All the best, Tom Thomas S. Dye, Ph.D. T. S. Dye & Colleagues, Archaeologists, Inc. Phone: (808) 529-0866 Fax: (808) 529-0884 http://www.tsdye.com [[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. [[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.
Re: [R] pair matching
If the matching need not be one-to-one, then you can just compute the
Euclidean distances between the two vectors, then in each row (or
column, which ever corresponds to the shorter vector) and find the
smallest. This should be fairly easy to do.
Andy
From: Thomas S. Dye
>
> Given two numeric vectors of possibly unequal length, I'd
> like to pair
> each element of the shorter vector with an element of the longer
> vector such that the sum of squared differences between the pairs is
> minimized. Can someone point me to an R function or an
> algorithm for
> accomplishing this?
>
> All the best,
> Tom
>
> Thomas S. Dye, Ph.D.
> T. S. Dye & Colleagues, Archaeologists, Inc.
> Phone: (808) 529-0866 Fax: (808) 529-0884
> http://www.tsdye.com
>
>
>
> [[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.
>
Notice: This e-mail message, together with any attachme...{{dropped:12}}
__
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.
[R] pair matching
Given two numeric vectors of possibly unequal length, I'd like to pair each element of the shorter vector with an element of the longer vector such that the sum of squared differences between the pairs is minimized. Can someone point me to an R function or an algorithm for accomplishing this? All the best, Tom Thomas S. Dye, Ph.D. T. S. Dye & Colleagues, Archaeologists, Inc. Phone: (808) 529-0866 Fax: (808) 529-0884 http://www.tsdye.com [[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.
