I'll try #1. You can use outer twice: outer(outer(x,y, "/"),z,function(a,b),"^")
In general I suppose you could write an "outer.n" function that would take the vectors and the functions to be applied and loop through them. And I think that outer will then take care of the dimnames for you. (Taking care of #2, and, I think, #3.) Hope this helps. Matt Wiener -----Original Message----- From: Marc Vandemeulebroecke [mailto:[EMAIL PROTECTED] Sent: Friday, July 11, 2003 7:48 AM To: [EMAIL PROTECTED] Subject: [R] short puzzles Dear R users, can someone help with these short puzzles? 1) Is there a function like outer() that evaluates a three-argument function on a threedimensional grid - or else how to define such a function, say, outer.3()? E.g., calculate (x/y)^z on (x,y,z) element of {1,2,3}x{3,4}x{4,5} and return the results in a 3-dimensional array. I would naively use outer() on two of the arguments within a for() loop for the third argument and somehow glue the array together. Is there a better way? What about outer.4(), or even outer.n(), generalizing outer() to functions with an arbitrary number of arguments? 2) Define a function dimnames.outer() such that dimnames.outer(x, y, "*") returns, for x <- 1:2, y <- 2:3, the following matrix: y x 2 3 1 2 3 2 4 6 (Or does such such a function already exist?) 3) How to combine puzzle 1 and puzzle 2? A function dimnames.outer.n() would be a nice little tool. 4) How can I access, within a function, the name of a variable that I have passed to the function? E.g., letting a <- 2, and subsequently calling function f(a) as defined below, f <- function (x) { # How can I get "a" out of x? } 5) Finally: Letting x <- 2, how can I transform "x+y" into "2+y" (as some suitable object), or generally "func(x,y)" into "func(2,y)"? Many thanks, Marc -- Jetzt ein- oder umsteigen und USB-Speicheruhr als Prämie sichern! ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help ------------------------------------------------------------------------------ Notice: This e-mail message, together with any attachments, ...{{dropped}} ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
