Dear all,

I want to apply a function to list elements, two by two. I hoped that combn
would help me out, but I can't get it to work. A nested for-loop works, but
seems highly inefficient when you have large lists. Is there a more
efficient way of approaching this?

# Make some toy data
data(iris)
test <- vector("list",3)
for (i in 1:3){
    x <- levels(iris$Species)[i]
    tmp <- dist(iris[iris$Species==x,-5])
    test[[i]] <- tmp
}
names(test) <- levels(iris$Species)

# nested for loop works
for(i in 1:2){
    for(j in (i+1):3){
        print(all.equal(test[[i]],test[[j]]))
    }
}

# combn doesn't work
combn(test,2,all.equal)

Cheers
Joris
-- 
Joris Meys
Statistical Consultant

Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control

Coupure Links 653
B-9000 Gent

tel : +32 9 264 59 87
Joris.Meys@Ugent.be
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