Suleyman K
2011-Oct-29 13:08 UTC
[R] R help with different combinations of vectors of different sizes
Hi, I am trying to get different combinations of a vector of different size and find their sum. For example, if I have a vector (i,j) where i and j can be anything from 0 to 5, i get these combinations (0,0), (0,1), (1,0), (1,1), (2,0), ...... (5,5) and find sum of these as 0, 1, 1, 2, ..... , 10. I used outer functions to get this and it worked. What if I have a vector (i,j,k) where all i, j , and k can be anything from 0 to 5. I want to do the same thing here. Get all the combinations and sum them up. (0,0,0) (0,0,1), (0,1,0), (1,0,0), .... (5,5,5) How can I get these combinations and find their sums? Thank you very much in advance. Uka [[alternative HTML version deleted]]
R. Michael Weylandt
2011-Oct-29 14:46 UTC
[R] R help with different combinations of vectors of different sizes
Just add another outer wrapper:
outer(1:5, outer(1:5, 1:5, "+"), "+")
If you are going to arbitrarily long tuples, it may be worthwhile to
put this in a wrapper like so:
tupleSums <- function(vec, n){
stopifnot(all.equal(n, as.integer(n)))
n <- as.integer(n)
if (n == 1L) return(vec)
ans <- outer(vec, vec, "+")
if (n == 2L) return(ans)
else{
for (i in 3:n) ans <- outer(vec, ans, "+")
}
return(ans)
}
Though this really could be made much more efficient if you want:
e.g., for the n = 4 case, it would be better to take outer( outer(vec,
vec, "+"), outer(vec, vec, "+"), "+").
Michael
On Sat, Oct 29, 2011 at 9:08 AM, Suleyman K <s.karmv at gmail.com>
wrote:> Hi,
>
> I am trying to get different combinations of a vector of different size and
> find their sum. For example, if I have a vector (i,j) where i and j can be
> anything from 0 to 5, i get these combinations (0,0), (0,1), (1,0), (1,1),
> (2,0), ...... (5,5) and find sum of these as 0, 1, 1, 2, ..... , 10. I used
> outer functions to get this and it worked. What if I have a vector (i,j,k)
> where all i, j , and k can be anything from 0 to 5. I want to do the same
> thing here. Get all the combinations and sum them up. (0,0,0) (0,0,1),
> (0,1,0), (1,0,0), .... (5,5,5) How can I get these combinations and find
> their sums? Thank you very much in advance.
>
> Uka
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.
>
William Dunlap
2011-Oct-29 14:56 UTC
[R] R help with different combinations of vectors of different sizes
Another approach is to use expand.grid to create a data.frame of all possible combinations of elements of its input vectors: rowSums(expand.grid(0:5, 0:5, 0:5)) Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com> -----Original Message----- > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of R. Michael > Weylandt > Sent: Saturday, October 29, 2011 7:46 AM > To: Suleyman K > Cc: r-help at r-project.org > Subject: Re: [R] R help with different combinations of vectors of different sizes > > Just add another outer wrapper: > > outer(1:5, outer(1:5, 1:5, "+"), "+") > > If you are going to arbitrarily long tuples, it may be worthwhile to > put this in a wrapper like so: > > tupleSums <- function(vec, n){ > stopifnot(all.equal(n, as.integer(n))) > n <- as.integer(n) > if (n == 1L) return(vec) > ans <- outer(vec, vec, "+") > if (n == 2L) return(ans) > else{ > for (i in 3:n) ans <- outer(vec, ans, "+") > } > return(ans) > } > > Though this really could be made much more efficient if you want: > e.g., for the n = 4 case, it would be better to take outer( outer(vec, > vec, "+"), outer(vec, vec, "+"), "+"). > > Michael > > On Sat, Oct 29, 2011 at 9:08 AM, Suleyman K <s.karmv at gmail.com> wrote: > > Hi, > > > > I am trying to get different combinations of a vector of different size and > > find their sum. For example, if I have a vector (i,j) where i and j can be > > anything from 0 to 5, i get these combinations (0,0), (0,1), (1,0), (1,1), > > (2,0), ...... (5,5) and find sum of these as 0, 1, 1, 2, ..... , 10. I used > > outer functions to get this and it worked. What if I have a vector (i,j,k) > > where all i, j , and k can be anything from 0 to 5. I want to do the same > > thing here. Get all the combinations and sum them up. (0,0,0) (0,0,1), > > (0,1,0), (1,0,0), .... (5,5,5) How can I get these combinations and find > > their sums? Thank you very much in advance. > > > > Uka > > > > ? ? ? ?[[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help at 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. > > > > ______________________________________________ > R-help at 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.
uka
2011-Oct-29 15:06 UTC
[R] R help with different combinations of vectors of different sizes
Thank you very much both! That's exactly what I was trying to get. -- View this message in context: http://r.789695.n4.nabble.com/R-help-with-different-combinations-of-vectors-of-different-sizes-tp3950940p3950997.html Sent from the R help mailing list archive at Nabble.com.
David Winsemius
2011-Oct-29 15:10 UTC
[R] R help with different combinations of vectors of different sizes
On Oct 29, 2011, at 9:08 AM, Suleyman K wrote:> Hi, > > I am trying to get different combinations of a vector of different > size and > find their sum. For example, if I have a vector (i,j) where i and j > can be > anything from 0 to 5, i get these combinations (0,0), (0,1), (1,0), > (1,1), > (2,0), ...... (5,5) and find sum of these as 0, 1, 1, 2, ..... , 10. > I used > outer functions to get this and it worked. What if I have a vector > (i,j,k) > where all i, j , and k can be anything from 0 to 5. I want to do the > same > thing here. Get all the combinations and sum them up. (0,0,0) (0,0,1), > (0,1,0), (1,0,0), .... (5,5,5) How can I get these combinations and > find > their sums? Thank you very much in advance.You did say "combinations" rather than permutations, so: > colSums(combn(0:5, 3)) [1] 3 4 5 6 5 6 7 7 8 9 6 7 8 8 9 10 9 10 11 12 If you instead meant "permutations", then consider this: > rowSums(expand.grid(0:5,0:5, 0:5)) [1] 0 1 2 3 4 5 1 2 3 4 5 6 2 3 4 5 6 7 3 4 5 6 7 8 4 5 6 7 8 9 5 6 7 [34] 8 9 10 1 2 3 4 5 6 2 3 4 5 6 7 3 4 5 6 7 8 4 5 6 7 8 9 5 6 7 8 9 10 [67] 6 7 8 9 10 11 2 3 4 5 6 7 3 4 5 6 7 8 4 5 6 7 8 9 5 6 7 8 9 10 6 7 8 [100] 9 10 11 7 8 9 10 11 12 3 4 5 6 7 8 4 5 6 7 8 9 5 6 7 8 9 10 6 7 8 9 10 11 [133] 7 8 9 10 11 12 8 9 10 11 12 13 4 5 6 7 8 9 5 6 7 8 9 10 6 7 8 9 10 11 7 8 9 [166] 10 11 12 8 9 10 11 12 13 9 10 11 12 13 14 5 6 7 8 9 10 6 7 8 9 10 11 7 8 9 10 11 12 [199] 8 9 10 11 12 13 9 10 11 12 13 14 10 11 12 13 14 15 > table(rowSums(expand.grid(0:5,0:5, 0:5))) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 3 6 10 15 21 25 27 27 25 21 15 10 6 3 1 A056150 Number of combinations for each possible sum when throwing 3 (normal) dice. http://oeis.org/A056150> > Uka > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.David Winsemius, MD West Hartford, CT