numbers loop in R
On Fri, Apr 17, 2009 at 12:19 PM, jim holtman <jholtman at gmail.com> wrote:
try this:
matrixx<-function(A){
+ ? ? B=matrix(NaN,nrow=(A+1),ncol=4)
+ ? ? k <- 1
+ ? ? for (i in 3:A){
+ ? ? ? ? for (j in i:A) {
+ ? ? ? ? ? ? B[k,] <- c(NaN, i-2, i-1, j)
+ ? ? ? ? ? ? k <- k + 1
+ ? ? ? ? }
+ ? ? }
+ ? ? B
+ }
matrixx(5)
? ? [,1] [,2] [,3] [,4] [1,] ?NaN ? ?1 ? ?2 ? ?3 [2,] ?NaN ? ?1 ? ?2 ? ?4 [3,] ?NaN ? ?1 ? ?2 ? ?5 [4,] ?NaN ? ?2 ? ?3 ? ?4 [5,] ?NaN ? ?2 ? ?3 ? ?5 [6,] ?NaN ? ?3 ? ?4 ? ?5
Here's a solution without the loop. I think it illustrates the intent of the algorithm more clearly. candidates <- t(combn(5,3)) firstdiff <- candidates[,2] - candidates[, 1] cbind(NaN, candidates[firstdiff == 1, ]) Hadley