Question

I need two for loops. Like this:

for (i in seq_along(dat1)[25:30]) 
    for(j in seq_along(dat1)[2:7]) {
        print(summary(r <- lm(dat1[,j] ~ dat1[,i]+Jan+Nov, data=dat1)))
}

Now I would like to condition the output, that I only get the diagonals and not all possible permutations, so the first of i and the first of j. How do I do this?

I tried the if statement but if (i==j) doesn’t work and I don’t know how to specify it correctly.

Answer 1

You could try if ((i-23) == j). But the following command may be easier:

mapply(25:30, 2:7, function(i, j)
                             summary(lm(dat1[,j] ~ dat1[,i]+Jan+Nov, data=dat1)))

This will avoid the permutations you are not interested in.