Thanks Chuck. Interesting suggestion. Thanks to everyone for the help.
Bill On Sun, Aug 30, 2009 at 4:59 PM, Charles C. Berry<cbe...@tajo.ucsd.edu> wrote: > > > Bill, > > prod( cancor( A,B )$cor ) > > perhaps? > > Note that this accounts for linear transformations. > > HTH, > > Chuck > > 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@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:cbe...@tajo.ucsd.edu UC San Diego > http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 > > > ______________________________________________ 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.