Is this what you want:
> my.foo <- function( a, b ) a - b
> z <- combn(ncol(y), 2) # get all the combinations of 2 columns
> result <- do.call(cbind, lapply(seq(ncol(z)), function(.cols){
+ my.foo(y[,z[1,.cols]], y[, z[2, .cols]])
+ }))
>
>
> result
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13]
[,14] [,15] [,16] [,17] [,18] [,19] [,20] [,21] [,22] [,23] [,24]
[,25] [,26]
1 -1 -2 -3 -4 -5 -6 -7 -8 -1 -2 -3 -4 -5
-6 -7 -1 -2 -3 -4 -5 -6 -1 -2 -3
-4 -5
2 -2 -4 -6 -8 -10 -12 -14 -16 -2 -4 -6 -8 -10
-12 -14 -2 -4 -6 -8 -10 -12 -2 -4 -6
-8 -10
3 -3 -6 -9 -12 -15 -18 -21 -24 -3 -6 -9 -12 -15
-18 -21 -3 -6 -9 -12 -15 -18 -3 -6 -9
-12 -15
4 -4 -8 -12 -16 -20 -24 -28 -32 -4 -8 -12 -16 -20
-24 -28 -4 -8 -12 -16 -20 -24 -4 -8 -12
-16 -20
5 -5 -10 -15 -20 -25 -30 -35 -40 -5 -10 -15 -20 -25
-30 -35 -5 -10 -15 -20 -25 -30 -5 -10 -15
-20 -25
6 -6 -12 -18 -24 -30 -36 -42 -48 -6 -12 -18 -24 -30
-36 -42 -6 -12 -18 -24 -30 -36 -6 -12 -18
-24 -30
7 -7 -14 -21 -28 -35 -42 -49 -56 -7 -14 -21 -28 -35
-42 -49 -7 -14 -21 -28 -35 -42 -7 -14 -21
-28 -35
8 -8 -16 -24 -32 -40 -48 -56 -64 -8 -16 -24 -32 -40
-48 -56 -8 -16 -24 -32 -40 -48 -8 -16 -24
-32 -40
9 -9 -18 -27 -36 -45 -54 -63 -72 -9 -18 -27 -36 -45
-54 -63 -9 -18 -27 -36 -45 -54 -9 -18 -27
-36 -45
[,27] [,28] [,29] [,30] [,31] [,32] [,33] [,34] [,35] [,36]
1 -1 -2 -3 -4 -1 -2 -3 -1 -2 -1
2 -2 -4 -6 -8 -2 -4 -6 -2 -4 -2
3 -3 -6 -9 -12 -3 -6 -9 -3 -6 -3
4 -4 -8 -12 -16 -4 -8 -12 -4 -8 -4
5 -5 -10 -15 -20 -5 -10 -15 -5 -10 -5
6 -6 -12 -18 -24 -6 -12 -18 -6 -12 -6
7 -7 -14 -21 -28 -7 -14 -21 -7 -14 -7
8 -8 -16 -24 -32 -8 -16 -24 -8 -16 -8
9 -9 -18 -27 -36 -9 -18 -27 -9 -18 -9
>
> y
1 2 3 4 5 6 7 8 9
1 1 2 3 4 5 6 7 8 9
2 2 4 6 8 10 12 14 16 18
3 3 6 9 12 15 18 21 24 27
4 4 8 12 16 20 24 28 32 36
5 5 10 15 20 25 30 35 40 45
6 6 12 18 24 30 36 42 48 54
7 7 14 21 28 35 42 49 56 63
8 8 16 24 32 40 48 56 64 72
9 9 18 27 36 45 54 63 72 81
>
On Wed, Mar 25, 2009 at 9:03 AM, Ken-JP <kfmf...@gmail.com> wrote:
>
> Okay, this one is hard to put into words:
>
>> x <- 1:9; names(x) <- x
>> y <- x %o% x
>> y
>
> 1 2 3 4 5 6 7 8 9
> 1 1 2 3 4 5 6 7 8 9
> 2 2 4 6 8 10 12 14 16 18
> 3 3 6 9 12 15 18 21 24 27
> 4 4 8 12 16 20 24 28 32 36
> 5 5 10 15 20 25 30 35 40 45
> 6 6 12 18 24 30 36 42 48 54
> 7 7 14 21 28 35 42 49 56 63
> 8 8 16 24 32 40 48 56 64 72
> 9 9 18 27 36 45 54 63 72 81
>
>> my.foo( a, b ) { c <- a - b; #really more complex, but just to illustrate
>> }
>
> ---------------------------------------------------------------------
>
> What I would like to do is apply my.foo() which takes two columns, a and b,
> does an operation and returns another column c. The columns I want to feed
> into my.foo() are all the combinations of columns in y. So I want to apply
> my.foo( y[,1], y[,1] ) and then my.foo( y[,1], y[,2] ), etc... for all
> combinations() of the 10 columns in y.
>
> I would expect the final output to be 10x10x10. Passing 10 columns by 10
> columns to my.foo() which outputs a vector of 10 numbers at a time.
>
> ***So in essence, what I am trying to accomplish is like outer(), but
> instead of operating on atomic values, I want to operate on columns of y.
>
> I know I can use loops to accomplish this, but I would like to code as
> R-like as possible. I am learning a great deal about "how to think in R"
> from the excellent replies on this board.
>
> Thanks in advance for any suggestions.
>
>
>
> --
> View this message in context:
> http://www.nabble.com/Doing--o--that-operates-on-columns-instead-of-atomics-tp22701363p22701363.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
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