Well, a reproducible example would be nice =) not tested:
x = rnorm(10) y = rnorm(20) mymax <- function(t1, t2) apply(cbind(t1, t2), 1, max) sum(outer(x, y, mymax)) is this sth like what you need? b On Feb 1, 2007, at 1:18 PM, Jeffrey Racine wrote: > Greetings. > > For R gurus this may be a no brainer, but I could not find pointers to > efficient computation of this beast in past help files. > > Background - I wish to implement a Cramer-von Mises type test > statistic > which involves double sums of max(X_i,Y_j) where X and Y are > vectors of > differing length. > > I am currently using ifelse pointwise in a vector, but have a nagging > suspicion that there is a more efficient way to do this. Basically, I > require three sums: > > sum1: \sum_i\sum_j max(X_i,X_j) > sum2: \sum_i\sum_j max(Y_i,Y_j) > sum3: \sum_i\sum_j max(X_i,Y_j) > > Here is my current implementation - any pointers to more efficient > computation greatly appreciated. > > nx <- length(x) > ny <- length(y) > > sum1 <- 0 > sum3 <- 0 > > for(i in 1:nx) { > sum1 <- sum1 + sum(ifelse(x[i]>x,x[i],x)) > sum3 <- sum3 + sum(ifelse(x[i]>y,x[i],y)) > } > > sum2 <- 0 > sum4 <- sum3 # symmetric and identical > > for(i in 1:ny) { > sum2 <- sum2 + sum(ifelse(y[i]>y,y[i],y)) > } > > Thanks in advance for your help. > > -- Jeff > > -- > Professor J. S. Racine Phone: (905) 525 9140 x 23825 > Department of Economics FAX: (905) 521-8232 > McMaster University e-mail: [EMAIL PROTECTED] > 1280 Main St. W.,Hamilton, URL: > http://www.economics.mcmaster.ca/racine/ > Ontario, Canada. L8S 4M4 > > `The generation of random numbers is too important to be left to > chance' > > ______________________________________________ > 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. ______________________________________________ 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.