Smart! Thanks Crispin
> -----Original Message----- > From: Berwin Turlach [mailto:[EMAIL PROTECTED] > Sent: 06 October 2003 13:11 > To: Crispin Miller > Subject: Re: [R] Apply and its friends > > > >>>>> "CM" == Crispin Miller <[EMAIL PROTECTED]> writes: > > CM> Hi, > CM> Forgive a very basic question... > CM> I need to take two lists-of-lists, and apply a function to > CM> each pair of elements in the lists to return a single > CM> list... > CM> For example > > CM> l1 <- list(1:5,6:10,2:15) > CM> l2 <- list(1:8,4:12,1:19,4:20) > > CM> I could easily do an lapply across each of them, but is there > CM> a function that does a sort-of pairwise-apply across both > CM> together? > Not sure how you can do this in your case since one list has 3 > components and the other 4. :) > > But something like this should work: > > n <- min( length(l1), length(l2) ) > res <- sapply(1:n, function(x) sum(l1[[x]]) - sum(l2[[x]]) ) > > The first line calculates the minimum length of the two list. The > second one calls sapply with a function. The first argument is > essentially a vector with the components that we would like to use. > In this case I take the difference of the sum as an example. > > If you don't like to make use of global variables, you can pass on the > list on which you want to operate explicitly to the function that you > call in sapply: > > res <- sapply(1:n, function(x, d1, d2) sum(d1[[x]]) - > sum(d2[[x]]), d1=l1, d2=l2) > > Hope this helps. > > Cheers, > > Berwin Turlach > > ========================== Full address ============================ > Berwin A Turlach Tel.: +61 (8) 9380 3338 > (secr) > School of Mathematics and Statistics +61 (8) 9380 3383 > (self) > The University of Western Australia FAX : +61 (8) 9380 1028 > 35 Stirling Highway > Crawley WA 6009 e-mail: [EMAIL PROTECTED] > Australia http://www.maths.uwa.edu.au/~berwin > > -------------------------------------------------------- This email is confidential and intended solely for the use o...{{dropped}} ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
