[R] correlation between two 2D point patterns?

Charles C. Berry cberry at tajo.ucsd.edu
Sun Aug 30 17:59:55 CEST 2009


 	prod( cancor( A,B )$cor )


Note that this accounts for linear transformations.



On Sun, 30 Aug 2009, William Simpson wrote:

> Suppose I have two sets of (x,y) points like this:
> x1<-runif(n=10)
> y1<-runif(n=10)
> A<-cbind(x1,y1)
> x2<-runif(n=10)
> y2<-runif(n=10)
> B<-cbind(x2,y2)
> I would like to measure how similar the two sets of points are.
> Something like a correlation coefficient, where 0 means the two
> patterns are unrelated, and 1 means they are identical. And in
> addition I'd like to be able to assign a p-value to the calculated
> statistic.
> cor(x1,x2)
> cor(y1,y2)
> gives two numbers instead of one.
> cor(A,B)
> gives a correlation matrix
> I have looked a little at spatial statistics. I have seen methods
> that, for each point, search in some neighbourhood around it and then
> compute the correlation as a function of search radius. That is not
> what I am looking for. I would like a single number that summarises
> the strength of the relationship between the two patterns.
> I will do procrustes on the two point sets first, so that if A is just
> a rotated, translated, scaled, reflected version of B the two patterns
> will superimpose and the statistic I'm looking for will say there is
> perfect correspondence.
> Thanks very much for any help in finding such a statistic and
> calculating it using R.
> Bill
> ______________________________________________
> R-help at 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.

Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901

More information about the R-help mailing list